Patent Publication Number: US-2021164830-A1

Title: Polarization independent optoelectronic device and method

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. Non-Provisional application Ser. No. 16/207,670, titled “POLARIZATION INDEPENDENT OPTOELECTRONIC DEVICE AND METHOD” and filed on Dec. 3, 2018, which claims priority to U.S. Provisional Application 62/753,142, titled “POLARIZATION INDEPENDENT OPTOELECTRONIC DEVICE AND METHOD” and filed Oct. 31, 2018. U.S. Non-Provisional application Ser. No. 16/207,670 and U.S. Provisional Application 62/753,142 are incorporated herein by reference. 
    
    
     BACKGROUND 
     The rapid expansion in the use of the Internet has resulted in a demand for high speed communications links and devices, including optical links and devices. Optical links using fiber optics have many advantages compared to electrical links: large bandwidth, high noise immunity, reduced power dissipation, and minimal crosstalk. Optoelectronic integrated circuits made of silicon are useful since they can be fabricated in the same foundries used to make very-large scale integrated (VLSI) circuits. Optical communications technology is typically operating in the 1.3 μm and 1.55 μm infrared wavelength bands. The optical properties of silicon are well suited for the transmission of optical signals, due to the transparency of silicon in the infrared wavelength bands of 1.3 μm and 1.55 μm and the high refractive index of silicon. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  illustrates a top view of an optoelectronic device in accordance with some embodiments. 
         FIG. 2  illustrates a top view of an optoelectronic device comprising an optical combiner associated with the collection structure in accordance with some embodiments. 
         FIG. 3  illustrates a top view of an optoelectronic device comprising an electrical combining circuit associated with the collection structure in accordance with some embodiments. 
         FIG. 4  illustrates a circuit diagram of an electrical combining circuit comprising phase tuning elements in accordance with some embodiments. 
         FIG. 5A  illustrates a circuit diagram of a phase tuning element in accordance with some embodiments. 
         FIG. 5B  illustrates a circuit diagram of a phase tuning element in accordance with some embodiments. 
         FIG. 6  illustrates a top view of an optoelectronic device comprising multiple input ports and associated photodetectors in accordance with some embodiments. 
         FIGS. 7-15  illustrate views of scattering structures in accordance with some embodiments. 
         FIG. 16  illustrates a flow diagram of a method for phase aligning scattered electromagnetic radiation in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     Optoelectronic devices are employed to communicate optical signals, through a medium, such as a fiber optic cable, for example. On a receiving end of the medium, an optoelectronic receiver collects incident electromagnetic radiation and performs an optical-to-electrical conversion to allow processing of the information carried on the incident electromagnetic radiation. In some embodiments, an optoelectronic device comprises a scattering structure to scatter the incident electromagnetic radiation and a collection structure comprising input ports positioned proximate the scattering structure to collect the scattered electromagnetic radiation. The collected scattered electromagnetic radiation is provided to one or more photodetectors to perform an optical-to-electrical conversion. In some embodiments, the input ports are positioned at different radial positions around a periphery of the scattering structure, where the radial positions define oblique angles with respect to a center point of the scattering structure. In some embodiments, the scattering structure concurrently scatters incident electromagnetic radiation along non-orthogonal scattering axes, and the input ports are aligned in the collection structure with the non-orthogonal scattering axes. In some embodiments, the incident electromagnetic radiation exiting the medium is vertically polarized. However, the particular orientation of the orthogonal components of the vertically polarized electromagnetic radiation impinging on the collection structure is indeterminate. As will be described in detail below, the relative positioning of the input ports in the collection structure enhances polarization independence of the optoelectronic device. 
     Referring now to  FIG. 1 , a top view of a portion of an optoelectronic device  100  in accordance with some embodiments is illustrated. The optoelectronic device  100  comprises a scattering structure  105  and a collection structure  110 . In some embodiments, a medium  115 , such as a fiber optic cable, etc. terminates proximate the optoelectronic device  100 . Electromagnetic radiation  120  exits the medium  115  and impinges on the scattering structure  105 . Electromagnetic radiation reflected from the scattering structure  105  is received into the collection structure  110 . In some embodiments, the medium  115  is positioned at an oblique angle with respect to a horizontal plane comprising the scattering structure  105 . According to some embodiments, width and length dimensions of the scattering structure  105  are about twice the corresponding width and length dimensions of the medium  115 . In some embodiments, the electromagnetic radiation  120  is vertically polarized. A “vertically polarized” electromagnetic wave comprises an electric field vector and a magnetic field vector at a right angle with respect to the electric field vector. Both the electric field vector and magnetic field vector are perpendicular to the direction of propagation. According to some embodiments, the scattering structure  105  scatters the electromagnetic radiation  120  along scattering axes  125 A,  125 B,  125 C that are non-orthogonal with respect to one another. In some embodiments, the number and orientation of the scattering axes  125 A,  125 B,  125 C varies. In accordance with some embodiments, certain scattering axes are orthogonal to one another, but non-orthogonal to other scattering axes, such that at least a first scattering axis  125 A is non-orthogonal with respect to at least a second scattering axis  125 B. 
     In some embodiments, the collection structure  110  comprises input ports  130 , which are referred to individually as input ports  130 ( 1 ) . . .  130 ( n ). In some embodiments, the input ports  130  are positioned around a periphery of the scattering structure  105 . In some embodiments, the input ports  130  collectively continuously cover an entire periphery of the scattering structure  105 . In some embodiments, particular adjacent input ports  130  collectively cover continuous portions of a periphery of the scattering structure  105 . In some embodiments, the input ports  130  cover portions of the periphery of the scattering structure  105  in a non-continuous manner. In some embodiments, the collection structure  110  comprises at least three input ports  130 . In some embodiments, the collection structure  110  is divided into at least three sectors, each sector having at least one input port  130 . According to some embodiments, the input ports  130  are silicon structures or wave guides that direct the incident electromagnetic radiation. 
     According to some embodiments, the input ports  130  are positioned at different radial positions around the scattering structure  105  with respect to a center point  135  of the scattering structure  105 . For example, the input port  130 ( 1 ) is at a first radial position  140 ( 1 ), and the input port  130 ( 2 ) is at a second radial position  140 ( 2 ). The radial positons  140 ( 1 ),  140 ( 2 ) define an oblique angle  145  with respect to the center point  135  of the scattering structure  105 . 
     According to some embodiments, certain input ports  130  are aligned with the scattering axes. For example, the input port  130 ( 3 ) is aligned with one end of the scattering axis  125 A, and the input port  130 ( 4 ) is aligned with an opposite end of the scattering axis  125 A. 
     Referring to  FIG. 2 , a top view of the optoelectronic device  100  comprising an optical combiner  200  associated with the collection structure  110  in accordance with some embodiments is illustrated. In some embodiments, the collection structure  110  comprises input ports  130  (which are referred to individually as  130 ( 1 ) . . .  130 ( n )) positioned around a periphery of the scattering structure  105 . The input ports  130  comprise wave guides that extend to the optical combiner  200 . According to some embodiments, the optical path lengths of the wave guides to the optical combiner  200  are substantially equal such that the signals propagated therein are phase aligned. In some embodiments, the input ports  130  and associated wave guides comprise silicon structures embedded in a dielectric material. In some embodiments, the optical combiner  200  is a multi-mode interferometer, such as a  6 : 1  multi-mode interferometer. An optical output of the optical combiner  200  is coupled to a photodetector  205 . The photodetector  205  outputs a signal having a property that is indicative of the intensity of the electromagnetic radiation output by the optical combiner  200 . For example, in some embodiments, the photodetector  205  outputs a current that is proportional to or otherwise indicative of the intensity of the electromagnetic radiation output by the optical combiner  200 . As another example, in some embodiments, a voltage generated at an output of the photodetector  205  is proportional to or otherwise indicative of the intensity of the electromagnetic radiation output by the optical combiner  200 . Thus, the output of the photodetector  205  is an electrical measure of the signal provided by the medium  115 . Transitions in the output of the photodetector  205  correspond to edges in the electromagnetic signal. 
     In some embodiments, the input ports  130 ( 1 ),  130 ( 4 ) are aligned with opposite ends of the scattering axis  125 A, the input ports  130 ( 2 ),  130 ( 5 ) are aligned with opposite ends of the scattering axis  125 B, and input ports  130 ( 3 ),  130 ( 6 ) are aligned with opposite ends of the scattering axis  125 C. According to some embodiments, the number and orientation of the scattering axes  125 A- 125 C generated by the scattering structure  105  corresponds to the number and position of the input ports  130 . In some embodiments, the layout of the input ports  130  defines a periphery of the scattering structure  105 . For example, the scattering structure  105  in  FIG. 2  has a hexagonal periphery corresponding to the layout of the input ports  130 . In some embodiments, the scattering structure  105  defines an N-sided polygon, where N equals the number of input ports  130  in the collection structure. In some embodiments, although the polygons have linear edges, the overall shape approximates a circle with respect to a center point of the scattering structure  105 . 
     Referring to  FIG. 3  a top view of the optoelectronic device  100  comprising an electrical combining circuit  300  associated with the collection structure  110  is illustrated in accordance with some embodiments. In some embodiments, the periphery of the scattering structure  105  and the layout of the input ports  130 ( 1 )- 130 ( 6 ) corresponds to that described above in reference to  FIG. 2 . In some embodiments, each input port  130 ( 1 )- 130 ( 6 ) is coupled to a respective photodetector  305 ( 1 )- 305 ( 6 ). In some embodiments, the photodetectors  305 ( 1 )- 305 ( 6 ) are germanium based PiN diodes and the dimensions of each photodetectors are about 20 um in length and about 0.5 um in width. 
     In some embodiments, the photodetectors  305 ( 1 )- 305 ( 6 ) are coupled to an amplifier  310  in the electrical combining circuit  300  that generates a voltage proportional to a magnitude of a current received at an input of the electrical combining circuit  300 . Each of the photodetectors  305 ( 1 )- 305 ( 6 ) generates an output signal indicative of or proportional to the electromagnetic radiation passing through the associated input port  130 ( 1 )- 130 ( 6 ). The electrical combining circuit  300  combines the individual signals from the photodetectors  305 ( 1 )- 305 ( 6 ) to generate an output signal providing an electrical measure of the signal provided by the medium  115 . Transitions in the output of the electrical combining circuit  300  correspond to edges in the electromagnetic signal. 
     Referring to  FIG. 4 , a circuit diagram of an electrical combining circuit  400  comprising phase tuning elements  405  is illustrated in accordance with some embodiments. In some embodiments, the phase tuning elements  405  are coupled between the photodetectors  305  (e.g., the photodetectors  305 ( 1 )- 306 ( 6 ) in  FIG. 3 ) and an amplifier  410 . The phase tuning elements  405  allow phase alignment of the individual signals from the photodetectors  305 . According to some embodiments, the phase tuning elements  405  are configured by measuring phase differences between the individual photodetectors  305  and adjusting a variable delay generated by the phase tuning elements  405 . In some embodiments, a rising or falling edge in the output signal of each photodetector  305  is detected. The delay generated by each phase tuning element  405  is adjusted until the falling or rising edges are phase aligned across the photodetectors  305 . In some embodiments, a controller  415  dynamically tunes the phase tuning elements  405  during operation of the optoelectronic device  100 . In some embodiments, the phase tuning elements  405  are statically configured based on characterization tests performed on the optoelectronic device  100  during a design phase. 
     Referring to  FIG. 5A , a circuit diagram of a phase tuning element  405  is illustrated in accordance with some embodiments. In some embodiments, the phase tuning element  405  comprises delay stages  505  that introduce a delay in the signal propagating through the phase tuning element  405 . In some embodiments, each delay stage  505  comprises a resistor  510  and a capacitor  515 . In some embodiments, the total delay of the phase tuning element  405  is configured by varying the number of delay stages  500 . In some embodiments, one or more of the resistors  510  are variable resistors, where the resistance is varied based on a bias voltage applied to the resistor  510 , such as applied by the controller  415 . In some embodiments, one or more of the capacitors  515  are variable capacitors, where the capacitance is varied based on a bias voltage applied to the capacitor  515 , such as applied by the controller  415 . 
     Referring to  FIG. 5B , a circuit diagram of a phase tuning element  405  is illustrated in accordance with some embodiments. In some embodiments, the phase tuning element  405  comprises delay stages  520  that introduce a delay in the signal propagating through the phase tuning element  405 . In some embodiments, each delay stage  520  comprises an inductor  525  and a capacitor  530 . In some embodiments, the total delay of the phase tuning element  405  is configured by varying the number of delay stages  520 . In some embodiments, one or more of the inductors  525  are variable inductors, where the inductance is varied based on a bias voltage applied to the inductor  525 , such as applied by the controller  415 . In some embodiments, one or more of the capacitors  530  are variable capacitors, where the capacitance is varied based on a bias voltage applied to the capacitor  530 , such as applied by the controller  415 . 
     Referring to  FIG. 6 , a top view of the optoelectronic device  100  comprising a large number of input ports  130 , each having an associated photodetector  305 , according to some embodiments is illustrated. In some embodiments, the electrical combining circuit  300  illustrated in  FIG. 3  is coupled to the photodetectors  305  illustrated in  FIG. 6 . In some embodiments, the electrical combining circuit  400  illustrated in  FIG. 4  is coupled to the photodetectors  305  illustrated in  FIG. 6 . As seen in  FIG. 6 , as the number of photodetectors  305  increases, the periphery of the scattering structure  105  approaches a circular shape. According to some embodiments, the number of input ports  130  and associated photodetectors  305  vary depending on the available circuit area around the scattering structure  105 . In some embodiments, with the scattering structure  105  having a perimeter of about 62 um and the photodetectors  305  having a width of about 0.5 um and a pitch of about 2 um, the number of photodetectors  305  is 31. 
     Referring to  FIGS. 7-15  various views of scattering structures are illustrated in accordance with some embodiments. According to some embodiments, the scattering structure may be employed in the optoelectronic devices  100  described above. 
     Referring to  FIG. 7 , a top view of a scattering structure  105 A is illustrated in accordance with some embodiments. In some embodiments, the scattering structure  105 A comprises pillars  700  arranged in a grid  705 . In some embodiments, the spacing of the pillars  700  in the grid  705  is periodic. In some embodiments, the spacing of the pillars  700  in the grid  705  is irregular. According to some embodiments, the pillars  700  have a circular horizontal cross-sectional shape. The circular horizontal cross-sectional shape of the pillars  700  results in a large number of non-orthogonal scattering axes (not illustrated). In some embodiments, the scattering structure  105 A is employed with the optoelectronic device  100  of  FIG. 6  to facilitate the large number of radially positioned input ports  130 . 
     Referring to  FIG. 8 , a top view of a scattering structure  105 B is illustrated in accordance with some embodiments. In some embodiments, the scattering structure  105 B comprises pillars  800  arranged in a grid  805 . In some embodiments, the spacing of the pillars  800  in the grid  805  is periodic. In some embodiments, the spacing of the pillars  800  in the grid  805  is irregular. According to some embodiments, the pillars  800  have a triangular horizontal cross-sectional shape. The triangular horizontal cross-sectional shape of the pillars  800  results in the electromagnetic radiation being scattered along the scattering axes  125 A,  25 B,  125 C. In some embodiments, each edge of a pillar  800  is referred to as a facet, where each pillar has at least one facet oriented perpendicular to one of the scattering axes  125 A,  125 B,  125 C. In some embodiments, each facet of a pillar  800  is oriented perpendicular to a different one of the scattering axes  125 A,  125 B,  125 C. In some embodiments, the scattering structure  105 B is employed with the optoelectronic device  100  of  FIGS. 3 and 4 . 
     Referring to  FIGS. 9-11 , a top view, an isometric view, and a cross-section view of a scattering structure  105 C, respectively, are illustrated in accordance with some embodiments. In some embodiments, the scattering structure  105 C comprises pillars  900  arranged in a grid  905 . In some embodiments, the spacing of the pillars  900  in the grid  905  is periodic. In some embodiments, the spacing of the pillars  900  in the grid  905  is irregular. According to some embodiments, the pillars  900  each have a lower member  900 A and an upper member  900 B positioned on the lower member  900 A. According to some embodiments, the lower member  900 A and the upper member  900 B have different horizontal cross-sectional shapes. In some embodiments, the lower member  900 A has a trapezoidal horizontal cross-sectional shape. In some embodiments, the upper member  900 B has a circular horizontal cross-sectional shape. Varying the horizontal cross-sectional shapes of the lower member  900 A and the upper member  900 B allows the creation of various arrangements of non-orthogonal scattering axes for the scattering structure  105 C, for example. In some embodiments, the circular horizontal cross-sectional shape results in substantially even scattering of the incident electromagnetic radiation toward the collection structure  110 . In some embodiments, polygon shapes are employed to provide multiple scattering axes, and as the number of faces in the polygon increases, the scattering characteristics approach that of a circle. 
     Referring to  FIG. 11 , a cross-section view of the grid  905  along line  11 - 11  shown in  FIG. 9  according to some embodiments is illustrated. In some embodiments, the scattering structure  105 C is formed on a substrate having a semiconductor-on-insulator (SOI) configuration that comprises a bulk semiconductor layer  1100 , a buried insulation layer  1105 , a first semiconductor layer  1110  in which the lower members  900 A are formed, and a second semiconductor layer  1115  in which the upper members  905 B are formed. In some embodiments, the first semiconductor layer  1110  and the second semiconductor layer  1115  may comprise the same or different compositions of materials. In some embodiments, the first semiconductor layer  1110  and the second semiconductor layer  1115  are portions of the same semiconductor layer that are differentiated by an etching process. In some embodiments, the buried insulation layer  1105  is exposed between the pillars  900 . According to some embodiments, patterned etching processes are performed to define the lower member  900 A and the upper member  900 B. In some embodiments, the bulk semiconductor layer  1100  is silicon. In some embodiments, the bulk semiconductor layer  1100  is a material other than silicon, such as silicon-germanium, a III-V compound semiconductor material, etc. In some embodiments, the buried insulation layer  1105  is silicon dioxide or other suitable dielectric. In some embodiments, the first semiconductor layer  1110  and the second semiconductor layer  1115  are silicon. 
     Referring to  FIGS. 12-13 , a top view and an isometric view of a scattering structure  105 D, respectively, in accordance with some embodiments are illustrated. In some embodiments, the scattering structure  105 D comprises pillars  1200  arranged in a grid  1205 . In some embodiments, the spacing of the pillars  1200  in the grid  1205  is periodic. In some embodiments, the spacing of the pillars  1200  in the grid  1205  is irregular. According to some embodiments, the pillars  1200  each have a lower member  1200 A and upper member  1200 B positioned on the lower member  1200 A. According to some embodiments, pillars  1200  are similar to the pillars  900  described in  FIGS. 9-11 , with the exception that an opening  1210  is defined through the upper member  1200 B and the lower member  1200 A to expose the underlying buried insulation layer  1105  (shown in  FIG. 11 ). 
     Referring to  FIGS. 14-15 , a top view and an isometric view of a scattering structure  105 E, respectively, in accordance with some embodiments are illustrated. In some embodiments, the scattering structure  105 E comprises pillars  1400  arranged in a grid  1405 . In some embodiments, the spacing of the pillars  1400  in the grid  1405  is periodic. In some embodiments, the spacing of the pillars  1400  in the grid  1405  is irregular. According to some embodiments, the pillars  1400  each have a lower member  1400 A and upper members  1400 B( 1 )- 1400 B( 3 ) positioned on the lower member  1400 A. According to some embodiments, the lower member  1400 A has a trapezoidal horizontal cross-sectional shape. In some embodiments, the upper members  1400 B( 1 )- 1400 B( 3 ) have triangular horizontal cross-sectional shapes. Varying the horizontal cross-sectional shapes of the lower members  1400 A and upper members  1400 B( 1 )- 1400 B( 3 ) allows the creation of various arrangements of non-orthogonal scattering axes for the scattering structure  105 E, for example. 
     In some embodiments, the scattering structures illustrated in  FIGS. 7-15  are implemented on a semiconductor wafer. In some embodiments, the semiconductor wafer has a semiconductor-on-insulator ( 501 ) configuration that comprises a bulk semiconductor layer, a buried insulation layer, and at least one semiconductor layer in which the elements of the scattering structures are formed.  FIG. 11  illustrates such an SOI substrate in reference to one embodiment of a scattering structure  105 C. The same substrate configuration may be employed for the other scattering structures  105 A,  105 B  105 D,  105 E illustrated in  FIGS. 7, 8, and 12-15 , for example. 
     Referring to  FIG. 16  a flow diagram of a method  1600  for phase aligning scattered electromagnetic radiation is illustrated in accordance with some embodiments. At  1605 , electromagnetic radiation is scattered along a first scattering axis to create first scattered electromagnetic radiation and along a second scattering axis to create second scattered electromagnetic radiation. In some embodiments, the first scattering axis and the second scattering axis are non-orthogonal. At  1610 , the first scattered electromagnetic radiation is detected to yield first detected radiation, and the second scattered electromagnetic radiation is detected to yield second detected radiation. At  1615 , the first detected radiation is phase aligned with the second detected radiation. 
     In some embodiments, an optoelectronic device comprises a scattering structure to scatter the incident electromagnetic radiation and a collection structure comprising input ports positioned proximate the scattering structure to collect the scattered electromagnetic radiation. The collected scattered electromagnetic radiation is provided to one or more photodetectors to perform an optical-to-electrical conversion. In some embodiments, the incident electromagnetic radiation exiting the medium is vertically polarized. However, the particular orientation of the orthogonal components of the vertically polarized electromagnetic radiation impinging on the collection structure is indeterminate. The relative positioning of the input ports in the collection structure enhances polarization independence of the optoelectronic device. 
     In some embodiments, a device includes a scattering structure and a collection structure. The scattering structure is arranged to concurrently scatter incident electromagnetic radiation along a first scattering axis and along a second scattering axis. The first scattering axis and the second scattering axis are non-orthogonal. The collection structure is arranged to collect the scattered electromagnetic radiation and includes a first input port aligned with the first scattering axis and a second input port aligned with the second scattering axis. 
     In some embodiments, a device includes a scattering structure and a collection structure. The scattering structure is arranged to scatter incident electromagnetic radiation. The collection structure is arranged around a periphery of the scattering structure to collect the scattered electromagnetic radiation. The collection structure includes a first input port positioned at a first radial position around the periphery of the scattering structure and a second input port positioned at a second radial position around the periphery of the scattering structure. The first radial position and the second radial positon define an oblique angle with respect to a center point of the scattering structure. 
     In some embodiments, a method includes scattering electromagnetic radiation along a first scattering axis to create first scattered electromagnetic radiation and along a second scattering axis to create second scattered electromagnetic radiation. The first scattering axis and the second scattering axis are non-orthogonal. The first scattered electromagnetic radiation is detected to yield first detected radiation and the second scattered electromagnetic radiation is detected to yield second detected radiation. The first detected radiation is phase aligned with the second detected radiation. 
     The foregoing outlines features of several embodiments so that those of ordinary skill in the art may better understand various aspects of the present disclosure. Those of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of various embodiments introduced herein. Those of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 
     Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter of the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing at least some of the claims. 
     Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. Also, it will be understood that not all operations are necessary in some embodiments. 
     It will be appreciated that layers, features, elements, etc. depicted herein are illustrated with particular dimensions relative to one another, such as structural dimensions or orientations, for example, for purposes of simplicity and ease of understanding and that actual dimensions of the same differ substantially from that illustrated herein, in some embodiments. Additionally, a variety of techniques exist for forming the layers, regions, features, elements, etc. mentioned herein, such as at least one of etching techniques, planarization techniques, implanting techniques, doping techniques, spin-on techniques, sputtering techniques, growth techniques, or deposition techniques such as chemical vapor deposition (CVD), for example. 
     Moreover, “exemplary” is used herein to mean serving as an example, instance, illustration, etc., and not necessarily as advantageous. As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application and the appended claims are generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B and/or the like generally means A or B or both A and B. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used, such terms are intended to be inclusive in a manner similar to the term “comprising”. Also, unless specified otherwise, “first,” “second,” or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first element and a second element generally correspond to element A and element B or two different or two identical elements or the same element. 
     Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others of ordinary skill in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure comprises all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.