PATENT DOCUMENT

Publication Number: US-12125865-B2
Application Number: US-202117464550-A
Country: US
Kind Code: B2

Title: Electromagnetic radiation detectors integrated with immersion lenses

Abstract:
An electromagnetic radiation detector pixel includes a set of epitaxial layers and a lens. The set of epitaxial layers defines an electromagnetic radiation absorber. The lens is directly bonded to the set of epitaxial layers.

Claims:
What is claimed is: 
     
       1. An electromagnetic radiation detector pixel, comprising:
 a set of epitaxial layers defining,
 an electromagnetic radiation absorber; and 
 a stepped electrical contact on the electromagnetic radiation absorber; 
 
 a lens directly bonded to the set of epitaxial layers; and 
 a conductor; wherein,
 the stepped electrical contact has a first surface at a first distance from the lens and a second surface at a second distance from the lens, the second distance greater than the first distance; 
 the lens is directly bonded to the first surface; and 
 the conductor is electrically connected to the second surface and spaced apart from the lens. 
 
 
     
     
       2. The electromagnetic radiation detector pixel of  claim 1 , further comprising a set of one or more bond-facilitating layers disposed between the set of epitaxial layers and the lens. 
     
     
       3. The electromagnetic radiation detector pixel of  claim 2 , wherein the set of one or more bond-facilitating layers comprises a layer of silicon dioxide (SiO 2 ). 
     
     
       4. The electromagnetic radiation detector pixel of  claim 2 , wherein the set of one or more bond-facilitating layers comprises a layer of silicon nitride (SiN). 
     
     
       5. The electromagnetic radiation detector pixel of  claim 2 , wherein the set of one or more bond-facilitating layers comprises:
 a layer of silicon nitride (SiN); and 
 a layer of silicon dioxide (SiO 2 ). 
 
     
     
       6. The electromagnetic radiation detector pixel of  claim 1 , wherein:
 the electromagnetic radiation absorber comprises indium gallium arsenide (InGaAs); and 
 the lens comprises silicon (Si). 
 
     
     
       7. The electromagnetic radiation detector pixel of  claim 1 , further comprising an air gap between the conductor and the lens. 
     
     
       8. The electromagnetic radiation detector pixel of  claim 1 , further comprising a silicon dioxide (SiO 2 ) fill material disposed around a portion of the stepped electrical contact, and disposed between the conductor and the lens. 
     
     
       9. The electromagnetic radiation detector pixel of  claim 1 , further comprising a dielectric disposed between a portion of the conductor and a portion of the set of epitaxial layers. 
     
     
       10. The electromagnetic radiation detector pixel of  claim 9 , wherein the dielectric comprises a first dielectric, the electromagnetic radiation detector pixel further comprising:
 a second dielectric disposed on the conductor, with at least a portion of the conductor between the first dielectric and the second dielectric; and 
 a silicon dioxide (SiO 2 ) fill material disposed around a portion of the stepped electrical contact, and disposed between the second dielectric and the lens. 
 
     
     
       11. The electromagnetic radiation detector pixel of  claim 1 , wherein the set of epitaxial layers comprises at least one buffer layer disposed on a side of the electromagnetic radiation absorber opposite the stepped electrical contact. 
     
     
       12. A front-side illumination (FSI) electromagnetic radiation detector pixel, comprising:
 an indium gallium arsenide (InGaAs) electromagnetic radiation absorber; 
 a stepped electrical contact on the InGaAs electromagnetic radiation absorber, the stepped electrical contact having a first surface offset from a second surface, the first surface and the second surface facing a same direction; 
 a silicon (Si) lens directly bonded to the first surface; 
 a set of one or more bond-facilitating layers disposed between the first surface and the Si lens, the set of one or more bond-facilitating layers including silicon dioxide (SiO 2 ); and 
 a conductor disposed between the InGaAs electromagnetic radiation absorber and the SI lens and in electrical contact with the stepped electrical contact. 
 
     
     
       13. The FSI electromagnetic radiation detector pixel of  claim 12 , further comprising an air gap between the conductor and the Si lens. 
     
     
       14. The FSI electromagnetic radiation detector pixel of  claim 12 , further comprising a planarized silicon dioxide (SiO 2 ) fill between the conductor and the Si lens.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a nonprovisional of, and claims the benefit under 35 U.S.C. § 119(e) of, U.S. Provisional Patent Application No. 63/169,101, filed Mar. 31, 2021, the contents of which are incorporated herein by reference as if fully disclosed herein. 
    
    
     FIELD 
     The described embodiments relate to the detection of electromagnetic radiation and, more particularly, to electromagnetic radiation detectors integrated with immersion lenses. 
     BACKGROUND 
     Sensors are included in many of today&#39;s electronic devices, including electronic devices such as smartphones, computers (e.g., tablet computers or laptop computers), wearable electronic devices (e.g., electronic watches, smart watches, or health monitors), game controllers, navigation systems (e.g., vehicle navigation systems or robot navigation systems), and so on. Sensors may variously sense the presence of objects, distances to objects, proximities of objects, movements of objects (e.g., whether objects are moving, or the speed, acceleration, or direction of movement of objects), compositions of objects, and so on. One useful type of sensor is the electromagnetic radiation detector. 
     SUMMARY 
     Embodiments of the systems, devices, methods, and apparatus described in the present disclosure are directed to electromagnetic radiation detectors having one or more electromagnetic radiation detector pixels (“detector pixels”) and, more particularly, to electromagnetic radiation detectors integrated with immersion lenses. An individual detector pixel of an electromagnetic radiation detector may be integrated with an immersion lens in a one-to-one relationship or, alternatively, in a many-to-one or one-to-many relationship. Some of the described embodiments are directed to front-side illumination (FSI) electromagnetic radiation detectors that are integrated with immersion lenses, and some of the described embodiments are directed to back-side illumination (BSI) electromagnetic radiation detectors that are integrated with immersion lenses. 
     A common aspect of the disclosed embodiments is that a lens (an immersion lens) may be directly bonded to a layer of material forming part of the electromagnetic radiation detector. As used herein, a “direct bond” is a bond that does not rely on or otherwise use an adhesive, but is instead a molecular or chemical bond (i.e., a non-adhesive bond). 
     Some of the electromagnetic radiation detectors described herein are configured for short-wave infrared (SWIR) electromagnetic radiation detection and use indium gallium arsenide (InGaAs) electromagnetic radiation absorbers. However, the techniques described herein with respect to SWIR electromagnetic radiation detection and/or InGaAs electromagnetic radiation absorbers are applicable to electromagnetic radiation detectors configured for other wavelength detection ranges and/or for other electromagnetic radiation detectors that use other types of electromagnetic radiation absorbers. 
     In a first aspect, the present disclosure describes an electromagnetic radiation detector pixel. The electromagnetic radiation detector pixel may include a set of epitaxial layers and a lens. The set of epitaxial layers may define an electromagnetic radiation absorber. The lens may be directly bonded to the set of epitaxial layers. 
     In a second aspect, the present disclosure describes a front-side illumination (FSI) electromagnetic radiation detector pixel. The FSI electromagnetic radiation detector pixel may include an indium gallium arsenide (InGaAs) electromagnetic radiation absorber, and a stepped electrical contact on the InGaAs electromagnetic radiation absorber. The stepped electrical contact may have a first surface offset from a second surface, with the first surface and the second surface facing a same direction. A silicon (Si) lens may be directly bonded to the first surface. A set of one or more bond-facilitating layers may be disposed between the first surface and the lens. The bond-facilitating layer(s) may include a layer of silicon dioxide (SiO 2 ). A conductor may be disposed between the InGaAs electromagnetic radiation absorber and the lens, and may be in electrical contact with the stepped electrical contact. 
     In a third aspect, the present disclosure describes a back-side illumination (BSI) electromagnetic radiation detector pixel. The BSI electromagnetic radiation detector pixel may include a layered structure. The layered structure may have a first side and a second side, with the second side opposite the first side. An electromagnetic radiation absorber may be grown on the first side of the layered structure. A lens may be directly bonded to the second side of the layered structure. Electromagnetic radiation received through the lens may propagate through the layered structure to the electromagnetic radiation absorber. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1    shows an example cross-sectional elevation of an electromagnetic radiation detector pixel having a set of layers; 
         FIG.  2    shows a first example cross-sectional elevation of an FSI electromagnetic radiation detector pixel; 
         FIG.  3    shows a second example cross-sectional elevation of an FSI electromagnetic radiation detector pixel; 
         FIG.  4    shows a third example cross-sectional elevation of an FSI electromagnetic radiation detector pixel; 
         FIG.  5    shows a fourth example cross-sectional elevation of an FSI electromagnetic radiation detector pixel; 
         FIG.  6    shows an example plan view of an FSI electromagnetic radiation detector pixel, which detector pixel may be generally constructed as described with reference to any of  FIGS.  1 - 5   ; 
         FIG.  7    shows a fifth example cross-sectional elevation of an FSI electromagnetic radiation detector pixel; 
         FIG.  8    shows an example cross-sectional elevation of a BSI electromagnetic radiation detector pixel; 
         FIGS.  9 A and  9 B  show an example of a device that includes a set of sensors; 
         FIGS.  10 A and  10 B  show another example of a device that includes a set of sensors; 
         FIG.  11    shows an example of an earbud that includes a set of sensors; 
         FIG.  12    shows an example method of making an FSI electromagnetic radiation detector pixel; 
         FIG.  13    shows an example method of making a BSI electromagnetic radiation detector pixel; and 
         FIG.  14    shows a sample electrical block diagram of an electronic device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof), and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     When detecting low levels of electromagnetic radiation using an electromagnetic radiation detector pixel, shot noise from dark current can degrade the signal-to-noise ratio (SNR) of the detector pixel&#39;s desired photocurrent. The desired photocurrent is proportional to the number of photons collected and scales (but not necessarily proportionally) with the area of the detector pixel. Hence, reducing the area of the detector pixel decreases the dark current. However, decreasing the area of the detector pixel tends to decrease the number of photons that can potentially be collected (e.g., by reducing the collection area of the detector pixel), and thus also decreases the desired photocurrent, which can offset some or all of the SNR gain achieved by reducing the dark current. To increase the number of photons that can potentially be collected by a smaller detector pixel, a lens (e.g., a condenser lens) may be placed over the detector pixel to focus photons received within a larger area onto a smaller collection area (i.e., onto a detector pixel having a smaller collection area). 
     In some cases, a lens (e.g., a condenser lens) may be formed directly on a detector pixel by etching the lens into a layer of the detector pixel. For example, a lens may be etched into the substrate of a backside illumination (BSI) detector pixel. However, in some cases it may be desirable to form a lens apart from a detector pixel and then attach the lens to the detector pixel. Forming the lens apart from the detector pixel may provide various benefits. For example, forming the lens apart from the detector pixel allows the lens to be made from a different material than the material(s) that may be available in the detector pixel stack. A different lens material, having a higher refractive index, may allow the lens to condense more electromagnetic radiation. A different lens material may also lower the cost of a lens or improve its manufacturability (e.g., a silicon (Si) lens may be easier to manufacture than an indium phosphide (InP) lens), without significantly impacting the material decisions for the rest of the detector pixel. 
     In a BSI detector pixel that includes one or more buffer layers (e.g., layers which are configured to transition the lattice constant between that of the substrate and of an electromagnetic radiation absorber), the presence of the buffer layers can negatively impact the performance of the BSI detector pixel. Specifically, the defects typically found in the buffer layer(s) increase the dark current within the detector, and the buffer layer(s) may absorb electromagnetic radiation of a desired wavelength (i.e., electromagnetic radiation that would otherwise be absorbed by an intended electromagnetic radiation absorber) in a manner that cannot be captured by the detector pixel (and thus is lost for purposes of SNR). If a lens is formed on the BSI detector pixel&#39;s substrate, the buffer layer(s) cannot be removed. However, when a lens is formed apart from the detector pixel, the buffer layer(s) and the substrate on which they are formed may be partially or completely removed before the lens is attached to the back side of the detector pixel (thereby reducing the SNR loss that would otherwise result from the presence of the buffer layer(s)). Of note, the separately formed lens may be made using the same material(s) that are used in other layers of the detector pixel (e.g., the same material used to form the detector pixel&#39;s now removed substrate), but the lens may be incorporated into the detector pixel stack closer to an intended electromagnetic radiation absorber, and electromagnetic radiation does not have to travel through as great a depth of buffer layer(s). The presence of an air gap between a lens and a detector pixel&#39;s collection surface may result in a reduction of position/incident angle pairs of electromagnetic radiation (e.g., combinations of lateral locations and incident angles of electromagnetic radiation on the surface of the lens) that will reach the collection surface of the detector pixel (e.g., because of total internal reflection (TIR)). To focus electromagnetic radiation arriving at a large range of position/incident angle pairs onto a small detector pixel (i.e., a detector pixel having a small area collection surface), an immersion lens (i.e., a lens that is attached to the detector pixel without an air gap) may be adhesively bonded to the collection surface of the detector pixel, thus removing any air gap between the lens and the detector pixel&#39;s collection surface. However, for electromagnetic radiation having incident angles greater than the critical angle of the lens/adhesive interface, such electromagnetic radiation is unable to propagate across the lens/adhesive interface and may still experience TIR within the lens. To increase the range of position/incident angle pairs from which a detector pixel may collect electromagnetic radiation (i.e., to provide a detector pixel with a higher numerical aperture (NA)), the thickness of the adhesive needs to be made thinner. Unfortunately, currently available adhesives can only be made so thin. To achieve a greater numerical aperture (e.g., NA&gt;1.0), the adhesive has to be reduced in thickness more than is currently possible, or eliminated, so that the focal point of the lens can be positioned as close as possible to the collection surface (or detection plane) of the detector pixel. 
     The present disclosure describes an electromagnetic radiation detector pixel having a lens (an immersion lens) directly bonded to one or more other structures of the electromagnetic radiation detector pixel (though not necessarily to a surface of an electromagnetic radiation absorber or to the material that actually collects (absorbs) photons). As previously mentioned, a “direct bond” is defined herein as a bond that does not rely on or otherwise use an adhesive, but is instead a molecular or chemical bond (i.e., a non-adhesive bond) Eliminating both air and adhesive from the interface between a detector pixel&#39;s collection surface and an attached lens increases the SNR of the detector pixel, while preserving the advantages of manufacturing the lens and remainder of the detector pixel stack separately. 
     The constructions and techniques described herein can be applied to electromagnetic radiation detector pixels that are tailored for the detection of various ranges of electromagnetic radiation wavelengths, or to electromagnetic radiation detector pixels that are capable of detecting a wide range of (or any) electromagnetic radiation wavelengths. Although the described techniques are described primarily with reference to wideband SWIR detector pixels, the techniques are generally applicable to all kinds of electromagnetic radiation detector pixels. Detector pixels that are configured to detect SWIR are useful because most of the electromagnetic radiation within this range of wavelengths is only minimally absorbed by atmospheric components such as water, oxygen, and carbon dioxide and, thus, this range is a good range for sensing other materials or components (e.g., particulate matter, skin, blood, and so on). 
     One type of electromagnetic radiation detector is an InGaAs detector. Some InGaAs detectors include a layer of InGaAs (an electromagnetic radiation absorber) that is epitaxially grown directly on a substrate (e.g., an indium phosphide (InP) substrate) in a lattice-matched configuration and used in a front side illumination (FSI) configuration. Such an electromagnetic radiation detector may have low dark current and a high SNR. 
     To extend the absorption range of an InGaAs detector to longer electromagnetic radiation wavelengths, a set of one or more buffer layers can be grown on a substrate, and an InGaAs layer (an electromagnetic radiation absorber) can be grown on the set of one or more buffer layers in a non-lattice-matched configuration. Such an InGaAs detector can be configured to receive electromagnetic radiation through its front side (i.e., in an FSI configuration, in which electromagnetic radiation is received by the detector without first passing through the substrate) or through its back side (i.e., in a BSI configuration, in which electromagnetic radiation is received by the detector after passing through the substrate and/or the buffer layer(s)). 
     Electromagnetic radiation detector pixels may also take other forms, and in some cases may include electromagnetic radiation absorbers formed of gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), silicon (Si), germanium (Ge), mercury cadmium telluride (HgCdTe), indium arsenide (InAs), indium antimonide (InSb), indium arsenide antimonide (InAsSb), gallium antimonide (GaSb), other Type-II superlattice (T2SL) structures, or other materials or combinations of materials. These types of electromagnetic radiation absorbers, or other types, may be variously formed on InP or other types of substrates, depending on the application, and may be formed on a substrate with or without one or more buffer layers separating the electromagnetic radiation absorber from the substrate. In some cases, more than one electromagnetic radiation absorber and/or set of buffer layers may be formed on a substrate. In some embodiments, the composition of an immersion lens that is directly bonded to such material(s) may need to be formed of a material other than silicon, since silicon is only transmissive to certain wavelengths (or ranges of wavelengths) of electromagnetic radiation. 
     The above and other embodiments and techniques are described with reference to  FIGS.  1 - 14   . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
     Directional terminology, such as “top”, “bottom”, “upper”, “lower”, “front”, “back”, “over”, “under”, “above”, “below”, “left”, “right”, etc. is used with reference to the orientation of some of the components in some of the figures described below. Because components in various embodiments can be positioned in a number of different orientations, directional terminology is used for purposes of defining relative positions of various structures, and not absolute positions. For example, a first structure described as being “above” a second structure and “below” a third structure is also “between” the second and third structures, and would be “above” the third structure and “below” the second structure if the stack of structures were to be flipped. Also, as used herein, the phrase “at least one of” preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list. The phrase “at least one of” does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at a minimum one of any of the items, and/or at a minimum one of any combination of the items, and/or at a minimum one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or one or more of each of A, B, and C. Similarly, it may be appreciated that an order of elements presented for a conjunctive or disjunctive list provided herein should not be construed as limiting the disclosure to only that order provided. 
     As used herein, a “substrate” refers to a block or mass of common material. As used herein, a “layer” refers to one or more materials that are typically, but not necessarily, parallel to the top surface and/or bottom surface of a substrate or another layer. 
       FIG.  1    shows an example cross-sectional elevation of an electromagnetic radiation detector pixel  100  having a set of layers  102 . Some of the layers may be homogeneous, and some of the layers may be heterogeneous and subdivided into different regions having different compositions. In some cases, a portion of multiple layers may be removed (e.g., etched away), and a structure spanning multiple layers may be grown or deposited. 
     At least one layer in the set of layers  102  may include an electromagnetic radiation absorber (e.g., one or more materials (or material layers) that individually or collectively accumulate a charge when exposed to electromagnetic radiation  108 , which charge can be measured). In some cases, the electromagnetic radiation absorber may only accumulate charge when exposed to a particular range or ranges of electromagnetic radiation wavelengths. The range of electromagnetic radiation wavelengths may in some cases include a range of SWIR electromagnetic radiation wavelengths, but may alternatively encompass a different range of electromagnetic radiation wavelengths, which different range of electromagnetic radiation wavelengths may be a range of electromagnetic radiation wavelengths that overlaps or is wholly outside the SWIR range. 
     In some cases, the detector pixel  100  may be configured as an FSI detector pixel. In some of these embodiments, a stepped electrical contact may be formed on an electromagnetic radiation absorber that is within the set of layers  102  and near the lens  104 , and the lens  104  may be directly bonded to the stepped electrical contact. The electrical contact may be stepped (i.e., have different surfaces formed at different levels) so that an electrical connection may be made to a surface of the electrical contact without adding thickness to the interface between the lens  104  and the set of layers  102 . In alternative embodiments, the electrical contact may not be stepped, and an electrical connection may be made with the electrical contact between the lens  104  and the set of layers  102 . The lens  104  may in some cases be directly bonded to the stepped electrical contact without any type of intervening layer therebetween. In other cases, the lens  104  may be directly bonded to the stepped electrical contact via a set of one or more bond-facilitating layers including one or more layers of SiO 2  and/or one or more layers of SiN. In some cases, a SiO 2  fill may be used to planarize (e.g., chemically-mechanically polish) the set of layers  102  to the stepped electrical contact, and the entire bottom surface of the lens  104  may be directly bonded to the set of layers  102 . In other cases, the set of layers  102  may not be planarized to the stepped electrical contact and portions of the bottom surface of the lens  104  may be disposed over one or more air gaps between the lens  104  and the set of layers  102 . The lens  104  may also be directly bonded to an FSI detector pixel in other ways, and may or may not be attached to a stepped electrical contact. Examples of FSI detector pixels are described in more detail with reference to  FIGS.  2 - 7   . 
     In some cases, the detector pixel  100  may be configured as a BSI detector pixel. In some of these embodiments, the lens  104  may be directly bonded to an electromagnetic radiation absorber that is within the set of layers  102 , or to a buffer layer between the electromagnetic radiation absorber and the lens  104 , or to a substrate (e.g., an InP substrate) disposed between the lens  104  and the electromagnetic radiation absorber and/or buffer layer. The lens  104  may in some cases be directly bonded to the electromagnetic radiation absorber, buffer layer, or substrate without any type of intervening layer therebetween. In other cases, the lens  104  may be directly bonded to the electromagnetic radiation absorber, buffer layer, or substrate via a set of one or more bond-facilitating layers including one or more layers of SiO 2  and/or one or more layers of SiN. The lens  104  may also be directly bonded to a BSI pixel in other ways. An example of a BSI detector pixel is described in more detail with reference to  FIG.  8   . 
     In some embodiments, the lens  104  may be formed of, or include, Si. The lens  104  may have an electromagnetic radiation receiving surface  106  that is convex, has a Fresnel lens profile, or has another profile. 
     When the lens  104  is directly bonded to the set of layers  102  via a set of one or more bond-facilitating layers (i.e., one or more relatively thin layers that facilitate bonding without using an adhesive), the bond-facilitating layer(s) may have any thickness, but are preferably as thin as possible. By way of example, a set of one or more bond-facilitating layers consisting of layers of SiO 2  and/or SiN preferably has a thickness of 30 nanometers (nm) or less, although a set of one or more bond-facilitating layers consisting of layers of SiO 2  and/or SiN may be thicker. However, as the bond-facilitating layer(s) increase in thickness, directly bonding the lens  104  to the set of layers  102  may offer fewer and/or no advantages over adhesively bonding the lens  104  to the set of layers  102 . For example, the bond-facilitating layer(s) may include one or more low index materials, and if it not kept thin, electromagnetic radiation passing through the lens at greater incident angles may experience total internal reflection (TIR) within the lens and not propagate through to a detection surface of the detector pixel  100 , as might occur when using an adhesive. 
     In some cases, the detector pixel  100  may be incorporated into an array of detector pixels. 
       FIG.  2    shows a first example cross-sectional elevation of an FSI electromagnetic radiation detector pixel  200 . The detector pixel  200  is an example of the detector pixel described with reference to  FIG.  1   . In some cases, the detector pixel  200  may be incorporated into an array of detector pixels. 
     The detector pixel  200  may include a substrate  202  on which a set of epitaxial layers  204  is grown. The set of epitaxial layers  204  may define an electromagnetic radiation absorber  206 , which electromagnetic radiation absorber  206  may be formed from one or more materials (or one or more material layers) that individually or collectively absorb electromagnetic radiation in a manner that can be measured. The set of epitaxial layers  204  may also define a stepped electrical contact  208  on the electromagnetic radiation absorber  206 . In some cases, the substrate  202  may include InP. In some cases, the electromagnetic radiation absorber  206  may include InGaAs (e.g., one or more layers of InGaAs). 
     The stepped electrical contact  208  may in some cases be formed by doping a layer in the set of epitaxial layers, and then etching the doped layer; for example, a portion of a cap layer  210  within the set of epitaxial layers  204 . The cap layer  210  may be an upper layer in the set of epitaxial layers, and may be formed of the same or different materials as other layers in the set of epitaxial layers  204 . In cases where the electromagnetic radiation absorber  206  is formed of InGaAs, the cap layer  210  may be formed of InAsP. The cap layer  210  may be diffusion-doped. In some cases, the diffusion doping may be performed using Zinc (Zn), to create a p-well (e.g., a p +  well) within an n-doped cap layer  210 . The cap layer  210  may also or alternatively be doped with cadmium (Cd), magnesium (Mg), manganese (Mn), or beryllium (Be). Alternatively, the cap layer  210  may be doped to create an n-well (e.g., an n− well) within a p-doped cap layer  210 . The p+ well may then be etched to form a stepped electrical contact  208 . The etch may be performed as a wet etch (e.g., a solution-based chemical etch) or a dry etch (e.g., a plasma-based etch). In some cases, the electromagnetic radiation absorber  206  may also be an n-doped material (e.g., an n −  doped material), and the stepped electrical contact may include a p+ doped material. The differently doped electromagnetic radiation absorber  206  and stepped electrical contact  208  may form a p-n junction. 
     The stepped electrical contact  208  may have a number of surfaces that are parallel to the substrate  202 , with a first surface  212  disposed at a first distance from the substrate  202  and a second surface  214  disposed at a second distance from the substrate  202 . The second distance may be less than the first distance. 
     A lens  216  may be directly bonded to the first surface  212  of the stepped electrical contact  208 . When the detector pixel  200  is in use, electromagnetic radiation  218  may be received through the lens  216  and then propagate through the stepped electrical contact  208 , cap layer  210 , and any other layers to reach the electromagnetic radiation absorber  206  (and in some cases, a portion of the electromagnetic radiation  218  may propagate through the electromagnetic radiation absorber  206  to reach one or more other layers, such as one or more other layers defining another electromagnetic radiation absorber). 
     By way of example, the lens  216  may include Si (and in some cases may be formed entirely of Si). In some embodiments, the lens  216  may be formed individually, or as part of a lens array, by etching a Si lens on a Si on insulator (SOI) substrate (wafer), and then removing the SOI substrate. Dry etching, wet etching, and/or gray scale lithography may be used to form a lens  216  with a desired shape. In some cases, the lens  216  may have a thickness of about 100-200 micrometers (μm). 
     As shown, the lens  216  may be directly bonded to the stepped electrical contact  208  via a set of one or more bond-facilitating layers  220  disposed between the first surface  212  of the stepped electrical contact  208  and the lens  216 . The bond-facilitating layer(s)  220  may include one or more layers  222  of SiN on at least the first surface  212  of the stepped electrical contact  208 . The bond-facilitating layer(s)  220  may also include one or more layers of SiO 2    224 , which layers  224  may be deposited/grown on one or both of the SiN layer  222  and/or the lens  216  prior to the lens  216  being directly bonded to the first surface  212  of the stepped electrical contact  208 . Providing a layer of SiO 2  on both the lens  216  and the SiN layer  222  prior to bonding enables the formation of a covalent bond, having superior strength. 
     To reverse bias the p-n junction formed by the electromagnetic radiation absorber  206  and the stepped electrical contact  208 , a first electrode  226  (or conductor) may be formed on the substrate  202 , opposite the set of epitaxial layers  204 , and a second electrode  228  (or conductor) may be electrically connected to the stepped electrical contact  208 . The second electrode  228  may be spaced apart from the lens  216 . To prevent the second electrode  228  from being unintentionally shorted to the set of epitaxial layers  204  (e.g., to the cap layer  210 ), a dielectric  230  (e.g., a layer of SiN) may be disposed between a portion of the second electrode  228  and a portion of the set of epitaxial layers  204 , to electrically isolate the second electrode  228  from the electromagnetic radiation absorber  206  and other epitaxial layers. 
     In some embodiments, the stepped electrical contact  208  may be formed, and then the dielectric  230  may be deposited on the portions of the cap layer  210  that surround the stepped electrical contact  208 . Another dielectric  222  (e.g., another layer  222  of SiN) may be deposited on the portions of the stepped electrical contact  208  that extend above the cap layer  210 , as well as on temporarily exposed portions of the dielectric  230  and on the second electrode  228 . One or more layers of SiO2  224  may then be deposited on the SiN layer  222  and/or on the bottom surface  232  of the lens  216  before the lens  216  is directly bonded to the first surface  212  of the stepped electrical contact  208 . 
     When the lens  216  is directly bonded to the first surface  212  of the stepped electrical contact  208 , a gap  234  (e.g., an air gap, other gas-filled gap, or vacuum-filled gap) may be formed between the second surface  214  of the stepped electrical contact  208  and the lens  216 . The gap  234  may extend to between the dielectric  222  and the lens  216 . In some embodiments, a hole may be formed in the lens material, and/or a channel may be formed in the dielectric  222  or a SiO 2  layer  224 , to allow air or other gases to escape from the gap  234 . 
     An advantage of the FSI detector pixel  200  is that the substrate  202  and/or set of epitaxial layers  204  (e.g., buffer layers within the set of epitaxial layers  204 , such as one or more buffer layers disposed between the electromagnetic radiation absorber  206  and the substrate  202 ) do not need to be thinned to increase the amount of electromagnetic radiation  218  that makes it to the electromagnetic radiation absorber  206  (though the substrate  202  and/or set of epitaxial layers  204  may still be thinned if desired, to decrease the height of the detector pixel  200 ). 
       FIG.  3    shows a second example cross-sectional elevation of an FSI electromagnetic radiation detector pixel  300 . The detector pixel  300  is an example of the detector pixel described with reference to  FIG.  1    and includes much of the structure of the detector pixel described with reference to  FIG.  2   . In some cases, the detector pixel  300  may be incorporated into an array of detector pixels. 
     The detector pixel  300  differs from the detector pixel described with reference to  FIG.  2    in that the set of one or more bond-facilitating layers  220  only includes the SiO 2  layer(s)  224 . Alternatively, the bond-facilitating layer(s)  220  may only include the SiN layer(s)  222 , although in the absence of a material such as SiO 2  on each of the lens  216  and the stepped electrical contact  208 , the bond between the lens  216  and the stepped electrical contact  208  may only be a hydrogen bond (versus a covalent bond). 
       FIG.  4    shows a third example cross-sectional elevation of an FSI electromagnetic radiation detector pixel  400 . The detector pixel  400  is an example of the detector pixel described with reference to  FIG.  1    and includes much of the structure of the detector pixel described with reference to  FIG.  2   . In some cases, the detector pixel  400  may be incorporated into an array of detector pixels. 
     The detector pixel  400  differs from the detector pixel described with reference to  FIG.  2    in that it does not include the SiN layer(s)  222  or the SiO 2  layer(s)  224 . 
       FIG.  5    shows a fourth example cross-sectional elevation of an FSI electromagnetic radiation detector pixel  500 . The detector pixel  500  is an example of the detector pixel described with reference to  FIG.  1    and includes much of the structure of the detector pixel described with reference to  FIG.  2   . In some cases, the detector pixel  500  may be incorporated into an array of detector pixels. 
     The detector pixel  500  differs from the detector pixel described with reference to  FIG.  2    in that it does not include any of an air gap, another type of gas-filled gap, or a vacuum-filled gap. Instead, the detector pixel  500  includes a fill material  502  (e.g., a SiO 2  fill) disposed around a portion of the stepped electrical contact  208 . The fill material  502  may in some cases be deposited around and over the stepped electrical contact  208 , and then planarized. In some cases, a SiO 2  fill material  502  may be planarized so that the total thickness of SiO 2  between the first surface  212  of the stepped electrical contact  208  and the lens  216  is 30 nm or less. Alternatively, the total thickness of SiO 2  may be between 0 and 100 nm, or in some cases greater than 100 nm. 
     Although the detector pixel  500  is shown with the set of one or more bond-facilitating layers  220  described with reference to  FIG.  2   , the bond-facilitating layer(s)  220  may in some cases not include the dielectric  222 . In other embodiments, a SiO 2  fill material  502  may be planarized to such an extent that there is little or no SiO 2  in the set of one or more bond-facilitating layers  220 . Thus, the bond-facilitating layer(s)  220  may include SiO 2  and SiN, just SiO 2 , or just SiN. 
       FIG.  6    shows an example plan view of an FSI electromagnetic radiation detector pixel  600 , which detector pixel  600  may be generally constructed as described with reference to any of  FIGS.  1 - 5   . In particular,  FIG.  6    shows a cap layer  620  (of a set of epitaxial layers) in which a stepped electrical contact  602  is formed. The stepped electrical contact  602  includes a first surface  604  that may be directly bonded to a lens  606 , and a second surface  608  that may be set back from (i.e., spaced apart from) a bonding surface of the lens  606 . An electrode  610  (a conductor) may be electrically connected to the second surface  608  of the stepped electrical contact  602 . 
     Optionally, a guard ring  612  may be formed around and electrically separated from the stepped electrical contact  602 . The guard ring  612  may also be set back from (i.e., spaced apart from) the bonding surface of the lens  606 . A second electrode  614  (a conductor) may be electrically connected to a surface of the guard ring  612 , similarly to how the electrode  610  is electrically connected to the second surface  608  of the stepped electrical contact  602 . 
     In  FIG.  6   , the electrodes  610  and  614  are shown to be electrically connected to the stepped electrical contact  602  and guard ring  612  near respective, parallel edges of the stepped electrical contact  602  and guard ring  612 . Alternatively, the electrodes  610  and  614  could be electrically connected to the stepped electrical contact  602  and guard ring  612  near respective, perpendicularly-oriented edges of the stepped electrical contact  602  and guard ring  612 . 
     Each of the electrodes  610 ,  614  may be routed between an electromagnetic radiation absorber and the lens  606 , and may be spaced apart from the lens  606 , as described with reference to the electrodes attached to the stepped electrical contacts in any of  FIGS.  1 - 5   . Each of the electrodes  610 ,  614  may be connected to respective, parallel routing conductors  616 ,  618  or other types of routing conductors. 
     By way of example, the lens  606  is shown to have a circular circumference. Alternatively, the circumference of the lens  606  may be oval, square, rectangular, oblong, or otherwise-shaped. Also by way of example, the lens  606  is shown to have a diameter greater than that of the stepped electrical contact  602 . In other embodiments, the diameter (or other dimensions) of the lens  606  may be greater or smaller. 
     In some cases, the detector pixel  600  may be incorporated into an array of detector pixels. 
       FIG.  7    shows a fifth example cross-sectional elevation of an FSI electromagnetic radiation detector pixel  700 , with the cross-section being taken along line VII-VII of  FIG.  6   . The detector pixel  700  is an example of the electromagnetic radiation detector pixel described with reference to  FIG.  1    and includes much of the structure of the detector pixel described with reference to  FIG.  2   . In some cases, the detector pixel  700  may be incorporated into an array of detector pixels. 
     The detector pixel  700  differs from the detector pixel described with reference to  FIG.  2    in that it includes a guard ring  612  and electrode  614  connected thereto, as described with reference to  FIG.  6   . 
     The guard ring  612  and electrode  614  structures, as well as any dielectrics or layers deposited thereon or thereunder, may also be incorporated into any of the FSI detector pixels described with reference to  FIGS.  3 - 5   . 
       FIG.  8    shows an example cross-sectional elevation of a BSI electromagnetic radiation detector pixel  800 . The detector pixel  800  is an example of the detector pixel described with reference to  FIG.  1   . In some cases, the detector pixel  800  may be incorporated into an array of detector pixels. 
     The detector pixel  800  may include a layered structure  802  having a first side  804  and a second side  806 , with the second side  806  opposite the first side  804 . An electromagnetic radiation absorber  808  may be grown on the first side  804  of the layered structure  802 , and in some cases may be considered a part of the layered structure  802 . In some cases, the electromagnetic radiation absorber  808  may include InGaAs (e.g., one or more layers of InGaAs). In some cases, the layered structure  802  may include a substrate (e.g., an InP substrate) on which a set of epitaxial layers  812 , including the electromagnetic radiation absorber, is grown. The layered structure  802  may also or alternatively include a set of buffer layers  814  (i.e., one or more buffer layers  814 ) positioned between the electromagnetic radiation absorber  808  and the substrate. As shown, the substrate, and in some cases some or all of the buffer layer(s)  814 , may be removed. Although some of the buffer layer(s) are shown in  FIG.  8   , all of the buffer layer(s) may be removed in some embodiments. 
     A lens  816  may be directly bonded to the second side  806  of the layered structure  802 . When the layered structure  802  includes the substrate, the lens  816  may be directly bonded to the substrate. However, in embodiments that do not include the substrate (e.g., because the substrate was removed to thin the detector pixel  800 ), the lens  816  may be directly bonded to a buffer layer in the set of buffer layers  814 . In embodiments that do not include the substrate or the set of buffer layers  814  (e.g., because the set of buffer layers  814  was not provided or removed, and because the substrate was removed), the lens  816  may be directly bonded to the electromagnetic radiation absorber  808 . The lens  816  may also be bonded to another electromagnetic radiation absorber within the layered structure  802 , or to another layer within the layered structure  802 . 
     In some cases, the detector pixel  800  may include an optional etch stop material  838 . The etch stop material  838  may aid in removal of a portion of the layered structure  802  (i.e., to aid in thinning of the layered structure  802  by removal of a substrate and/or some or all of the buffer layer(s)  814 ). 
     By way of example, the lens  816  may include Si (and in some cases may be formed entirely of Si). In some embodiments, the lens  816  may be formed individually, or as part of a lens array, by etching a Si lens on a Si on insulator (SOI) substrate (wafer), and then removing the SOI substrate. Dry etching, wet etching, and/or gray scale lithography may be used to form a lens  816  with a desired shape. In some cases, the lens  816  may have a thickness of about 100-200 micrometers (μm). 
     The lens  816  may in some cases be directly bonded to the electromagnetic radiation absorber  808 , a buffer layer, or a substrate without any type of intervening layer therebetween. In other cases, the lens  816  may be directly bonded to the electromagnetic radiation absorber  808 , buffer layer, or substrate via a set of one or more bond-facilitating layers  818  including one or more layers of SiO 2    820  and/or one or more layers of SiN  822 . 
     In some embodiments, a cap layer  824  (e.g., a layer of InAsP) may be formed on a side of the electromagnetic radiation absorber  808  opposite the layered structure  802 . The cap layer  824  may in some cases be an n +  doped material, and a p +  well  826  may be formed in the cap layer  824 . A first electrode  828  (a conductor) may be deposited on and electrically connected to the p +  well, and a dielectric  830  may be deposited on at least part of the n +  doped cap layer  824 . A second electrode  832  (a conductor) may be routed through or around the dielectric  830  and the electromagnetic radiation absorber  808  and electrically connected to a buffer layer in the set of buffer layers  814  (or to an N-contact layer below the electromagnetic radiation absorber  808 ). 
     The first and second electrodes may be electrically connected to corresponding electrodes of a readout integrated circuit  834  (ROIC). The ROIC  834  may include a device layer (e.g., for a transimpedance amplifier (TIA) or other detection/amplification circuit), metal layers for routing electrical signals through a readout circuit, top electrodes (e.g., metal contacts) for electrical interconnection to the electrodes  828 ,  832 , and so on. A function of the ROIC  834  may be to collect the photocurrent generated by the electromagnetic radiation absorber  808 , and pass it to an external contact or convert it to a voltage using a TIA and/or another circuit. 
     The electromagnetic radiation absorber  808  (which may have an n −  doping in some cases) in combination with the p +  well  826  forms a p-n junction. The p-n junction may be reverse-biased by applying a voltage across the electrodes  828 ,  832 . 
     When the detector pixel  800  is in use, electromagnetic radiation  836  may be received through the lens  816  and propagate through the layered structure  802  to the electromagnetic radiation absorber  808 . 
     An advantage of the BSI electromagnetic radiation detector pixel  800  is that the electrical connections to the electromagnetic radiation absorber  808  and p+ well  826  may be simpler to construct than the electrical connections of the FSI electromagnetic radiation absorbers described with reference to  FIGS.  2 - 7   . 
       FIGS.  9 A and  9 B  show an example of a device  900  (an electronic device) that includes a set of sensors. The sensors may be used, for example, to acquire biological information from the wearer or user of the device  900  (e.g., a heart rate, respiration rate, blood pressure, blood flow rate, blood oxygenation, blood glucose level, and so on), or to determine a status of the device  900  (e.g., whether the device  900  is being worn or a tightness of the device  900 ). The device&#39;s dimensions and form factor, and inclusion of a band  904  (e.g., a wrist band), suggest that the device  900  is an electronic watch, fitness monitor, or health diagnostic device. However, the device  900  could alternatively be any type of wearable device.  FIG.  9 A  shows a front isometric view of the device  900 , and  FIG.  9 B  shows a back isometric view of the device  900 . 
     The device  900  may include a body  902  (e.g., a watch body) and a band  904 . The body  902  may include an input or selection device, such as a crown  918  or a button  920 . The band  904  may be attached to a housing  906  of the body  902 , and may be used to attach the body  902  to a body part (e.g., an arm, wrist, leg, ankle, or waist) of a user. The body  902  may include a housing  906  that at least partially surrounds a display  908 . In some embodiments, the housing  906  may include a sidewall  910 , which sidewall  910  may support a front cover  912  ( FIG.  9 A ) and/or a back cover  914  ( FIG.  9 B ). The front cover  912  may be positioned over the display  908 , and may provide a window through which the display  908  may be viewed. In some embodiments, the display  908  may be attached to (or abut) the sidewall  910  and/or the front cover  912 . In alternative embodiments of the device  900 , the display  908  may not be included and/or the housing  906  may have an alternative configuration. 
     The display  908  may include one or more light-emitting elements including, for example, light-emitting elements that define a light-emitting diode (LED) display, organic LED (OLED) display, liquid crystal display (LCD), electroluminescent (EL) display, or other type of display. In some embodiments, the display  908  may include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover  912 . 
     In some embodiments, the sidewall  910  of the housing  906  may be formed using one or more metals (e.g., aluminum or stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). The front cover  912  may be formed, for example, using one or more of glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display  908  through the front cover  912 . In some cases, a portion of the front cover  912  (e.g., a perimeter portion of the front cover  912 ) may be coated with an opaque ink to obscure components included within the housing  906 . In some cases, all of the exterior components of the housing  906  may be formed from a transparent material, and components within the device  900  may or may not be obscured by an opaque ink or opaque structure within the housing  906 . 
     The back cover  914  may be formed using the same material(s) that are used to form the sidewall  910  or the front cover  912 . In some cases, the back cover  914  may be part of a monolithic element that also forms the sidewall  910 . In other cases, and as shown, the back cover  914  may be a multi-part back cover, such as a back cover having a first back cover portion  914 - 1  attached to the sidewall  910  and a second back cover portion  914 - 2  attached to the first back cover portion  914 - 1 . The second back cover portion  914 - 2  may in some cases have a circular perimeter and an arcuate exterior surface  916  (i.e., an exterior surface  916  having an arcuate profile). 
     The front cover  912 , back cover  914 , or first back cover portion  914 - 1  may be mounted to the sidewall  910  using fasteners, adhesives, seals, gaskets, or other components. The second back cover portion  914 - 2 , when present, may be mounted to the first back cover portion  914 - 1  using fasteners, adhesives, seals, gaskets, or other components. 
     A display stack or device stack (hereafter referred to as a “stack”) including the display  908  may be attached (or abutted) to an interior surface of the front cover  912  and extend into an interior volume of the device  900 . In some cases, the stack may include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other type of touch sensing elements), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect a touch applied to an outer surface of the front cover  912  (e.g., to a display surface of the device  900 ). 
     In some cases, a force sensor (or part of a force sensor system) may be positioned within the interior volume below and/or to the side of the display  908  (and in some cases within the device stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover  912  (or a location or locations of one or more touches on the front cover  912 ), and may determine an amount of force associated with each touch, or an amount of force associated with the collection of touches as a whole. The force sensor (or force sensor system) may alternatively trigger operation of the touch sensor (or touch sensor system), or may be used independently of the touch sensor (or touch sensor system). 
     The device  900  may include various sensors. In some embodiments, the device  900  may have a port  922  (or set of ports) on a side of the housing  906  (or elsewhere), and an ambient pressure sensor, ambient temperature sensor, internal/external differential pressure sensor, gas sensor, particulate matter concentration sensor, or air quality sensor may be positioned in or near the port(s)  922 . 
     In some cases, one or more skin-facing sensors  926  may be included within the device  900 . The skin-facing sensor(s)  926  may emit or transmit signals through the housing  906  (or back cover  914 ) and/or receive signals or sense conditions through the housing  906  (or back cover  914 ). For example, in some embodiments, one or more such sensors may include a number of electromagnetic radiation emitters (e.g., visible light and/or IR emitters) and/or a number of electromagnetic radiation detectors (e.g., visible light and/or IR detectors, such as electromagnetic radiation detectors including any of the detector pixels described herein). The sensors may be used, for example, to acquire biological information from the wearer or user of the device  900  (e.g., a heart rate, respiration rate, blood pressure, blood flow rate, blood oxygenation, blood glucose level, and so on), or to determine a status of the device  900  (e.g., whether the device  900  is being worn or a tightness of the device  900 ). 
     The device  900  may include circuitry  924  (e.g., a processor and/or other components) configured to determine or extract, at least partly in response to signals received directly or indirectly from one or more of the device&#39;s sensors, biological parameters of the device&#39;s user and/or a status of the device  900 , for example. In some embodiments, the circuitry  924  may be configured to convey the determined or extracted parameters or statuses via an output device of the device  900 . For example, the circuitry  924  may cause the indication(s) to be displayed on the display  908 , indicated via audio or haptic outputs, transmitted via a wireless communications interface or other communications interface, and so on. The circuitry  924  may also or alternatively maintain or alter one or more settings, functions, or aspects of the device  900 , including, in some cases, what is displayed on the display  908 . 
       FIGS.  10 A and  10 B  show another example of a device  1000  (an electronic device) that includes a set of sensors. The sensors may be used, for example, to acquire biological information from the user of the device  1000 , to determine parameters of an environment of the device  1000  (e.g., air quality), or to determine a distance to or composition of a target or object. The device&#39;s dimensions and form factor, including the ratio of the length of its long sides to the length of its short sides, suggest that the device  1000  is a mobile phone (e.g., a smartphone). However, the device&#39;s dimensions and form factor are arbitrarily chosen, and the device  1000  could alternatively be any portable electronic device including, for example a mobile phone, tablet computer, portable computer, portable music player, portable terminal, vehicle navigation system, robot navigation system, or other portable or mobile device. The device  1000  could also be a device that is semi-permanently located (or installed) at a single location (e.g., a door lock, thermostat, refrigerator, or other appliance).  FIG.  10 A  shows a front isometric view of the device  1000 , and  FIG.  10 B  shows a rear isometric view of the device  1000 . The device  1000  may include a housing  1002  that at least partially surrounds a display  1004 . The housing  1002  may include or support a front cover  1006  or a rear cover  1008 . The front cover  1006  may be positioned over the display  1004 , and may provide a window through which the display  1004  (including images displayed thereon) may be viewed by a user. In some embodiments, the display  1004  may be attached to (or abut) the housing  1002  and/or the front cover  1006 . 
     The display  1004  may include one or more light-emitting elements or pixels, and in some cases may be an LED display, an OLED display, an LCD, an EL display, a laser projector, or another type of electronic display. In some embodiments, the display  1004  may include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover  1006 . 
     The various components of the housing  1002  may be formed from the same or different materials. For example, a sidewall  1018  of the housing  1002  may be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). In some cases, the sidewall  1018  may be a multi-segment sidewall including a set of antennas. The antennas may form structural components of the sidewall  1018 . The antennas may be structurally coupled (to one another or to other components) and electrically isolated (from each other or from other components) by one or more non-conductive segments of the sidewall  1018 . The front cover  1006  may be formed, for example, using one or more of glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display  1004  through the front cover  1006 . In some cases, a portion of the front cover  1006  (e.g., a perimeter portion of the front cover  1006 ) may be coated with an opaque ink to obscure components included within the housing  1002 . The rear cover  1008  may be formed using the same material(s) that are used to form the sidewall  1018  or the front cover  1006 , or may be formed using a different material or materials. In some cases, the rear cover  1008  may be part of a monolithic element that also forms the sidewall  1018  (or in cases where the sidewall  1018  is a multi-segment sidewall, those portions of the sidewall  1018  that are non-conductive). In still other embodiments, all of the exterior components of the housing  1002  may be formed from a transparent material, and components within the device  1000  may or may not be obscured by an opaque ink or opaque structure within the housing  1002 . 
     The front cover  1006  may be mounted to the sidewall  1018  to cover an opening defined by the sidewall  1018  (i.e., an opening into an interior volume in which various electronic components of the device  1000 , including the display  1004 , may be positioned). The front cover  1006  may be mounted to the sidewall  1018  using fasteners, adhesives, seals, gaskets, or other components. 
     A display stack or device stack (hereafter referred to as a “stack”) including the display  1004  (and in some cases the front cover  1006 ) may be attached (or abutted) to an interior surface of the front cover  1006  and extend into the interior volume of the device  1000 . In some cases, the stack may also include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other type of touch sensing elements), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect a touch applied to an outer surface of the front cover  1006  (e.g., to a display surface of the device  1000 ). 
     The stack may also include one or an array of sensors  1016 , with the sensors positioned in front of or behind, or interspersed with, the light-emitting elements of the display  1004 . In some cases, an array of sensors  1016  may extend across an area equal in size to the area of the display  1004 . Alternatively, the array of sensors  1016  may extend across an area that is smaller than or greater than the area of the display  1004 , or may be positioned entirely adjacent the display  1004 . Although the array of sensors  1016  is shown to have a rectangular boundary, the array could alternatively have a boundary with a different shape, including, for example, an irregular shape. The array of sensors  1016  may be variously configured as an ambient light sensor, a light-emitting element (e.g., OLED) health sensor (e.g., age sensor), a touch sensor, a proximity sensor, a health sensor, a biometric sensor (e.g., a fingerprint sensor or facial recognition sensor), a camera, a depth sensor, and so on. The array of sensors  1016  may also or alternatively function as a proximity sensor, for determining whether an object (e.g., a finger, face, or stylus) is proximate to the front cover  1006 . In some embodiments, the array of sensors  1016  may provide the touch sensing capability (i.e., touch sensor) of the stack. 
     In some cases, a force sensor (or part of a force sensor system) may be positioned within the interior volume below and/or to the side of the display  1004  (and in some cases within the stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover  1006  (or indicating a location or locations of one or more touches on the front cover  1006 ), and may determine an amount of force associated with each touch, or an amount of force associated with the collection of touches as a whole. 
     As shown primarily in  FIG.  10 A , the device  1000  may include various other components. For example, the front of the device  1000  may include one or more front-facing cameras  1010  (including one or more image sensors), speakers  1012 , microphones, or other components  1014  (e.g., audio, imaging, and/or sensing components) that are configured to transmit or receive signals to/from the device  1000 . In some cases, a front-facing camera  1010 , alone or in combination with other sensors, may be configured to operate as a bio-authentication or facial recognition sensor. Additionally or alternatively, the array of sensors  1016  may be configured to operate as a front-facing camera  1010 , a bio-authentication sensor, or a facial recognition sensor. 
     The device  1000  may also include buttons or other input devices positioned along the sidewall  1018  and/or on a rear surface of the device  1000 . For example, a volume button or multipurpose button  1020  may be positioned along the sidewall  1018 , and in some cases may extend through an aperture in the sidewall  1018 . The sidewall  1018  may include one or more ports  1022  that allow air, but not liquids, to flow into and out of the device  1000 . In some embodiments, one or more sensors may be positioned in or near the port(s)  1022 . For example, an ambient pressure sensor, ambient temperature sensor, internal/external differential pressure sensor, gas sensor, particulate matter concentration sensor, or air quality sensor may be positioned in or near a port  1022 . 
     In some embodiments, the rear surface of the device  1000  may include a rear-facing camera  1024 . A flash or light source  1026  may also be positioned along the rear of the device  1000  (e.g., near the rear-facing camera). In some cases, the rear surface of the device  1000  may include multiple rear-facing cameras. 
     In some cases, the sensor(s)  1016 , the front-facing camera  1010 , the rear-facing camera  1024 , and/or other sensors positioned on the front, back, or sides of the device  1000  may emit or transmit signals through the housing  1002  (including the front cover  1006 , rear cover  1008 , or sidewall  1018 ) and/or receive signals or sense conditions through the housing  1002 . For example, in some embodiments, one or more such sensors may include a number of electromagnetic radiation emitters (e.g., visible light and/or IR emitters) and/or a number of electromagnetic radiation detectors (e.g., visible light and/or IR detectors, such as electromagnetic radiation detectors including any of the detector pixels described herein). 
     The device  1000  may include circuitry  1028  (e.g., a processor and/or other components) configured to determine or extract, at least partly in response to signals received directly or indirectly from one or more of the device&#39;s sensors, biological parameters of the device&#39;s user, a status of the device  1000 , parameters of an environment of the device  1000  (e.g., air quality), or a composition of a target or object, for example. In some embodiments, the circuitry  1028  may be configured to convey the determined or extracted parameters or statuses via an output device of the device  1000 . For example, the circuitry  1028  may cause the indication(s) to be displayed on the display  1004 , indicated via audio or haptic outputs, transmitted via a wireless communications interface or other communications interface, and so on. The circuitry  1028  may also or alternatively maintain or alter one or more settings, functions, or aspects of the device  1000 , including, in some cases, what is displayed on the display  1004 . 
       FIG.  11    shows an example of an earbud  1100  (an electronic device) that includes a set of sensors  1108 . The earbud  1100  may include a housing  1110 . The housing  1110  may hold a speaker  1102  that can be inserted into a user&#39;s ear, an optional microphone  1104 , and circuitry  1106  that can be used to acquire audio from the microphone  1104 , transmit audio to the speaker  1102 , and communicate audio between the speaker  1102 , the microphone  1104 , and one or more remote devices. The circuitry  1106  may communicate with a remote device wirelessly (e.g., via a wireless communications interface, using a Wi-Fi, BLUETOOTH®, or cellular radio communications protocol, for example) or via one or more wires (e.g., via a wired communications interface, such as a Universal Serial Bus (USB) communications interface). In addition to communicating audio, the circuitry  1106  may transmit or receive instructions and so on. 
     The sensors  1108  may be used, for example, to determine a proximity of a user to the earbud  1100  or speaker  1102 , or to receive input from a user. In some cases, a sensor may be used to identify a gesture of a user (e.g., a swipe gesture or a press gesture) made on a surface of the earbud  1100  or in free space in proximity to the earbud  1100 . The sensors  1108  may include skin-facing and/or non-skin-facing sensors. In some embodiments, one or more such sensors may include a number of electromagnetic radiation emitters (e.g., visible light and/or IR emitters) and/or a number of electromagnetic radiation detectors (e.g., visible light and/or IR detectors, such electromagnetic radiation detectors including any of the detector pixels described herein). 
     The circuitry  1106  may include a processor and/or other components that are configured to determine or extract, at least partly in response to signals received directly or indirectly from one or more of the sensors  1108 , information related to a proximity of a user, an input of a user, and so on. In some embodiments, the circuitry  1106  may be configured to convey the determined or extracted parameters or statuses via an output device of the earbud  1100 . For example, the circuitry  1106  may cause the indication(s) to be output via the speaker  1102  or a haptic device, transmitted via a wireless communications interface or other communications interface, and so on. The circuitry  1106  may also or alternatively maintain or alter one or more settings, functions, or aspects of the earbud  1100 , including, in some cases, what is output via the speaker  1102 . 
       FIG.  12    shows an example method  1200  of making an FSI electromagnetic radiation detector pixel. 
     At block  1202 , the method  1200  may include forming a set of epitaxial layers including an electromagnetic radiation absorber. 
     At block  1204 , the method  1200  may include directly bonding a lens to the set of epitaxial layers. In some cases, the lens may be directly bonded to a stepped electrical contact formed in the set of epitaxial layers. In some cases, the lens may be directly bonded to the set of epitaxial layers, or stepped electrical contact, by a set of bond-facilitating layers disposed between the set of epitaxial layers and the lens. 
       FIG.  13    shows an example method  1300  of making a BSI electromagnetic radiation detector pixel. 
     At block  1302 , the method  1300  may include forming a layered structure. The layered structure may include a set of epitaxial layers formed on a substrate. The set of epitaxial layers may include an electromagnetic radiation absorber, and in some cases may include a set of one or more buffer layers for transitioning a first lattice constant of the substrate to a second lattice constant of the electromagnetic radiation absorber. 
     At block  1304 , the method  1300  may include removing one or more of the substrate or some or all of the buffer layer(s) from the layered structure. 
     At block  1306 , the method  1300  may include directly bonding a lens to an epitaxial layer in the set of epitaxial layers. The epitaxial layer to which the lens is bonded may in some cases be one of the buffer layers or the electromagnetic radiation absorber. In some cases, the lens may be bonded to the epitaxial layer by a set of bond-facilitating layers disposed between the lens and the epitaxial layer. 
       FIG.  14    shows a sample electrical block diagram of an electronic device  1400 , which electronic device may in some cases be the device described with reference to  FIGS.  9 A- 9 B,  10 A- 10 B , or  11 . The electronic device  1400  may include an optional electronic display  1402  (e.g., a light-emitting display), a processor  1404 , a power source  1406 , a memory  1408  or storage device, a sensor system  1410 , or an input/output (I/O) mechanism  1412  (e.g., an input/output device, input/output port, or haptic input/output interface). The processor  1404  may control some or all of the operations of the electronic device  1400 . The processor  1404  may communicate, either directly or indirectly, with some or all of the other components of the electronic device  1400 . For example, a system bus or other communication mechanism  1414  can provide communication between the electronic display  1402 , the processor  1404 , the power source  1406 , the memory  1408 , the sensor system  1410 , and the I/O mechanism  1412 . 
     The processor  1404  may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions, whether such data or instructions is in the form of software or firmware or otherwise encoded. For example, the processor  1404  may include a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, or a combination of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. In some cases, the processor  1404  may provide part or all of the circuitry described with reference to  FIGS.  9 A- 11   . 
     It should be noted that the components of the electronic device  1400  can be controlled by multiple processors. For example, select components of the electronic device  1400  (e.g., the sensor system  1410 ) may be controlled by a first processor and other components of the electronic device  1400  (e.g., the electronic display  1402 ) may be controlled by a second processor, where the first and second processors may or may not be in communication with each other. 
     The power source  1406  can be implemented with any device capable of providing energy to the electronic device  1400 . For example, the power source  1406  may include one or more batteries or rechargeable batteries. Additionally or alternatively, the power source  1406  may include a power connector or power cord that connects the electronic device  1400  to another power source, such as a wall outlet. 
     The memory  1408  may store electronic data that can be used by the electronic device  1400 . For example, the memory  1408  may store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, and data structures or databases. The memory  1408  may include any type of memory. By way of example only, the memory  1408  may include random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such memory types. 
     The electronic device  1400  may also include a sensor system  1410 , including sensors positioned almost anywhere on the electronic device  1400 . In some cases, the sensor system  1410  may include one or more electromagnetic radiation emitters and/or detectors, positioned and/or configured as described with reference to any of  FIGS.  1 - 13   . The sensor system  1410  may be configured to sense one or more type of parameters, such as but not limited to, vibration; light; touch; force; heat; movement; relative motion; biometric data (e.g., biological parameters) of a user; air quality; proximity; position; connectedness; matter type; and so on. By way of example, the sensor system  1410  may include one or more of (or multiple of) a heat sensor, a position sensor, a proximity sensor, a light or optical sensor (e.g., an electromagnetic radiation emitter and/or detector), an accelerometer, a pressure transducer, a gyroscope, a magnetometer, a health monitoring sensor, and an air quality sensor, and so on. Additionally, the sensor system  1410  may utilize any suitable sensing technology, including, but not limited to, interferometric, magnetic, pressure, capacitive, ultrasonic, resistive, optical, acoustic, piezoelectric, or thermal technologies. 
     The I/O mechanism  1412  may transmit or receive data from a user or another electronic device. The I/O mechanism  1412  may include the electronic display  1402 , a touch sensing input surface, a crown, one or more buttons (e.g., a graphical user interface “home” button), one or more cameras (including an under-display camera), one or more microphones or speakers, one or more ports such as a microphone port, and/or a keyboard. Additionally or alternatively, the I/O mechanism  1412  may transmit electronic signals via a communications interface, such as a wireless, wired, and/or optical communications interface. Examples of wireless and wired communications interfaces include, but are not limited to, cellular and Wi-Fi communications interfaces. 
     The foregoing description, for purposes of explanation, uses specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art, after reading this description, that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art, after reading this description, that many modifications and variations are possible in view of the above teachings. 
     As described above, one aspect of the present technology may be the gathering and use of data available from various sources. The present disclosure contemplates that, in some instances, this gathered data may include personal information data (e.g., biological information) that uniquely identifies or can be used to identify, locate, contact, or diagnose a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to activate or deactivate various functions of the user&#39;s device, or gather performance metrics for the user&#39;s device or the user. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the United States (US), collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users may selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of advertisement delivery services, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide mood-associated data for targeted content delivery services. In yet another example, users can select to limit the length of time mood-associated data is maintained or entirely prohibit the development of a baseline mood profile. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the content delivery services, or publicly available information.

Metadata:
Filing Date: 20210901
Publication Date: 20241022
Grant Date: 20241022
Priority Date: 20210331
Inventors: MAHGEREFTEH, DANIEL
ARBORE, Mark Alan
MOREA, Matthew T.
CHEVALLIER, Romain F.
HSU, YUNG-YU
Assignee: APPLE INC
CPC Classifications: [{"code": "H10F77/413", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/199", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/184", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F77/413", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F77/306", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/024", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/021", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/1935", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/199", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/806", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/805", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/806", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10F39/184", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J5/0808", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L31/02327", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/14649", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/1464", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J5/0808", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/14625", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 83448277