Patent ID: 12230616

DETAILED DESCRIPTION

Specific details of several embodiments of representative SST devices and associated methods of manufacturing SST devices are described below. The term “SST” generally refers to solid-state transducer devices that include a semiconductor material as the active medium to convert electrical energy into electromagnetic radiation in the visible, ultraviolet, infrared, and/or other spectra. For example, SSTs include solid-state light emitters (e.g., LEDs, laser diodes, etc.) and/or other sources of emission other than electrical filaments, plasmas, or gases. In other embodiments, SSTs can include solid-state devices that convert electromagnetic radiation into electricity. The term solid state emitter (“SSE”) generally refers to the solid state components or light emitting structures that convert electrical energy into electromagnetic radiation in the visible, ultraviolet, infrared, and/or other spectra. SSEs include semiconductor LEDs, PLEDs, OLEDs, and/or other types of solid state devices that convert electrical energy into electromagnetic radiation in a desired spectrum. A person skilled in the relevant art will understand that the new, presently disclosed technology may have additional embodiments and that this technology may be practiced without several of the details of the embodiments described below with reference toFIGS.2A-9.

Reference herein to “one embodiment”, “an embodiment”, or similar formulations, means that a particular feature, structure, operation, or characteristic described in connection with the embodiment, is included in at least one embodiment of the present technology. Thus, the appearances of such phrases or formulations herein are not necessarily all referring to the same embodiment. Furthermore, various particular features, structures, operations, or characteristics may be combined in any suitable manner in one or more embodiments.

In particular embodiments, a solid state transducer system includes a support substrate and a solid state emitter carried by the support substrate. The solid state emitter can comprise a first semiconductor component, a second semiconductor component, and an active region between first and second semiconductor components. The system further includes a state device carried by the support substrate and positioned to detect a state of the solid state emitter and/or an electrical path of which the solid state emitter forms a part. The state device is formed from at least one state-sensing component having a composition different than that of the first semiconductor component, the second semiconductor component, and the active region. The state device and the solid state emitter can be stacked along a common axis. For example, in particular embodiments, the state device can include an electrostatic discharge protection device, a photosensor, or a thermal sensor. The state device can be formed integrally with the solid state emitter, using (in at least some embodiments) a portion of the same epitaxial growth substrate used to form the SSE. The state device can be formed above or below the stacking axis of the solid state emitter, directly along the axis, or off the axis, depending upon the particular embodiment.

FIG.2Ais a schematic illustration of a representative system290. The system290can include an SST device200, a power source291, a driver292, a processor293, and/or other subsystems or components294. The resulting system290can perform any of a wide variety of functions, such as backlighting, general illumination, power generation, sensing, and/or other functions. Accordingly, representative systems290can include, without limitation, hand-held devices (e.g., cellular or mobile phones, tablets, digital readers, and digital audio players), lasers, photovoltaic cells, remote controls, computers, lights and lighting systems, and appliances (e.g., refrigerators, for example). Components of the system290may be housed in a single unit or distributed over multiple, interconnected units (e.g., through a communications network). The components of the system290can also include local and/or remote memory storage devices, and any of a wide variety of computer-readable media.

In many instances, it is desirable to monitor the performance of the SST device200and/or the environment in which the SST device200operates, and make appropriate adjustments. For example, if the SST device200is subjected to an excessive voltage (e.g., an electrostatic discharge or “ESD”), it is desirable to protect the device with a diode or other non-linear circuit component. If the SST device200approaches an overheat condition, it may be desirable to reduce the current supplied to the device until the device cools down. If the SST device200includes a solid state lighting (SSL) device, and the light emitted by the device does not meet target emission specifications, it may be desirable to adjust the output of the device. In each of these representative examples, the system290can includes a state monitor or device295that monitors a state of the SST device200, and participates in or facilitates a response. In some cases, the state monitor295can act directly to provide a response. For example, a diode wired in parallel with the SST device200can respond directly to a high voltage by closing, causing the current to bypass the SST device200. In other embodiments, the state monitor295can respond with the assistance of another device, e.g., the processor293. For example, if the state monitor295is a photosensor, it can provide a signal to the processor293corresponding to a warmth, color and/or other characteristic of the emitted light, and the processor293can issue a responsive command to change the output of the SSE. In another embodiment, the state monitor295includes a thermistor, and can provide to the processor293a signal corresponding to a high temperature condition. The processor293can respond by directing the SST device200to reduce power or cease operation until the temperature falls, in order to reduce the impact of the elevated temperature on the SST device200.

Specific examples of state monitors that include ESD protection devices are described below with reference toFIGS.2B-5B. Certain features of these examples are also described in co-pending U.S. application Ser. No. 13/223,098 titled “Solid State Lighting Devices, Including Devices Having integrated Electrostatic Discharge Protection, and Associated Systems and Methods,” filed on Aug. 31, 2011, and incorporated herein by reference. Examples of state monitors that include photosensors are described below with reference toFIGS.6-8L, and examples of state monitors that include thermal sensors (e.g., thermistors) are described below with reference toFIG.9. In any of these embodiments, the state monitor can detect the state of the SSE (e.g., as is the case with a photosensor and a thermal sensor) and/or the state of an electrical path or circuit of which the SSE forms or part (as is the case with an ESD diode).

FIG.2Bis a cross-sectional view of an SST device200configured in accordance with embodiments of the presently disclosed technology. The SST device200can include an SSE202mounted to or otherwise carried by a support substrate230. The SST device200further includes a state monitor or device295in the form of an electrostatic discharge device250carried by the SSE202. Accordingly, the electrostatic discharge device250represents a specific example of a state monitor. As will be described further below, the electrostatic discharge device250can be manufactured to be integral with the SST device200(and in particular, the SSE202) e.g., to improve system reliability, manufacturability and/or performance, and/or to reduce system size.

The SSE202can include a first semiconductor material204, a second semiconductor material208. and an active region206between the first and second semiconductor materials204,208. In one embodiment, the first semiconductor material204is a P-type gallium nitride (“GaN”) material, the active region206is an indium gallium nitride (“InGaN”) material, and the second. semiconductor material208is an IN-type GaN material. In other embodiments, the semiconductor materials of the SSE202can include at least one of gallium arsenide (“GaAs”), aluminum gallium arsenide (“AlGaAs”), gallium arsenide phosphide (“GaAsP”), aluminum gallium indium phosphide (AlGaInP), gallium(III) phosphide (“GaP”), zinc selenide (“ZnSe”), boron nitride (“BN”), aluminum nitride (“AlN”), aluminum gallium nitride (“AlGaN”), aluminum gallium indium nitride (“AlGaInN”), and/or another suitable semiconductor material.

The illustrated electrostatic discharge device250includes an epitaxial growth substrate210and a semiconductor material216(e.g., a buffer material or layer). The electrostatic discharge device250further includes a first contact246(e.g., formed from a first conductive material) electrically connected to a via240that extends through the electrostatic discharge device250and through a portion of the SSE202. The first contact246electrically contacts a conductive (and typically reflective) material220below the active region206and can provide an external terminal for interfacing with a power source or sink. Accordingly, the conductive material220operates as a P-contact. The first contact246is electrically insulated in the via240from the surrounding semiconductor material216and portions of the SSE202by an insulator242. The illustrated electrostatic discharge device250further includes a second contact248(e.g., formed from a second conductive material) that doubles as an N-contact for the SSE202. Accordingly, the second contact248can extend over an upper surface209of the SSE202(e.g., in contact with the N-type second semiconductor material208). The second contact248is electrically insulated from the semiconductor material216by a second insulator244, and is transparent to allow radiation (e.g., visible light) to pass out through the external surface of the SST device200from the active region206. In the illustrated embodiment, the first contact246and the second contact248are shared by the SSE202and the electrostatic discharge device250. More specifically, the first contact246is electrically coupled to both the first semiconductor material204of the SSE202and the epitaxial growth substrate210of the electrostatic discharge device250. The second contact248is electrically coupled to both the second semiconductor material208of the SSE202and the epitaxial growth substrate210of the electrostatic discharge device250. Accordingly, the electrostatic discharge device250is connected in parallel with the SSE202. The conductive materials forming the first contact246, the second contact248and an electrical path through the via240can be the same or different, depending upon the particular embodiment. For example, the via240can include a third conductive material that is the same as the first conductive material, though it may be deposited in a separate step.

The SST device200can be coupled to a power source270that is in turn coupled to a controller280. The power source270provides electrical current to the SST device200, under the direction of the controller280. During normal operation, as current flows from the first semiconductor material204to the second semiconductor material208, charge-carriers flow from the second semiconductor material208toward the first semiconductor material204and cause the active region206to emit radiation. The radiation is reflected outwardly by the conductive, reflective material220. The electrostatic discharge device250provides a bypass path for current to flow between the first contact246and the second contact248under high (e.g., excessive) voltage conditions. In particular, the epitaxial growth substrate210between the first contact246and the second contact248can form a diode in parallel with the SSE202, but with the opposite polarity. During normal operating conditions, the bias of the epitaxial growth substrate210prevents current flow through it from the first contact246to the second contact248, forcing the current to pass through the SSE202. If a significant reverse voltage is placed across the contacts246,248, (e.g., during an electrostatic discharge event), the epitaxial growth substrate210becomes highly conductive in the reverse direction, allowing the reverse current to flow through it, thus protecting the SST device from the reverse current flow.

The present technology further includes methods of manufacturing SST devices. For example, one method of forming a SST device can include forming an SSE and an electrostatic discharge device from a common epitaxial growth substrate. Representative steps for such a process are described in further detail below with reference toFIGS.3A-3G.

FIGS.3A-3Gare partially schematic, cross-sectional views of a portion of a microelectronic substrate300undergoing a process of forming an embodiment of the SST device200described above, in accordance with embodiments of the technology.FIG.3Ashows the substrate300after a semiconductor material216(e.g., a buffer material or layer) has been disposed on the epitaxial growth substrate210. The epitaxial growth substrate210can be silicon (e.g., Si (1,0,0) or Si (1,1,1)), GaAs, silicon carbide (SiC), polyaluminum nitride (“pAlN”), engineered substrates with silicon epitaxial surfaces (e.g., silicon on polyaluminum nitride), and/or other suitable materials. The semiconductor material216can be the same material as the epitaxial growth substrate210or a separate material bonded to the epitaxial growth substrate210. For example, the epitaxial growth substrate210can be pAlN and the semiconductor material216can be Si (1,1,1). In any of these embodiments, the SSE202is formed on the semiconductor material216.

The SSE202includes the first semiconductor material204, the active region206, and the second semiconductor material208, which can be sequentially deposited or otherwise formed using chemical vapor deposition (“CVD”), physical vapor deposition (“PVD”), atomic layer deposition (“ALD”), plating, or other techniques known in the semiconductor fabrication arts. In the embodiment shown inFIG.3A, the second semiconductor material208is grown or formed on the semiconductor material216, the active region206is grown or formed on the second semiconductor material208, and the first semiconductor material204is grown or formed on the active region206. In one embodiment, N-type GaN (as described above with reference toFIG.2B) is positioned proximate to the epitaxial growth substrate210, but in other embodiments P-type GaN is positioned proximate to the epitaxial growth substrate210. In any of these embodiments, the SSE202can include additional buffer materials, stress control materials, and/or other materials, and/or the materials can have other arrangements known in the art.

In the embodiment shown inFIG.3A, a conductive, reflective material220ais formed over the first semiconductor material204. The conductive, reflective material220acan be silver (Ag), gold (Au), gold-tin (AuSn), silver-tin (AgSn), copper (Cu), aluminum (Al), or any other suitable material that can provide electrical contact and reflect light emitted from the active region206back through the first semiconductor material204, the active region206, and the second semiconductor material208, as described above with reference toFIG.2B. The conductive, reflective material220acan be selected based on its thermal conductivity, electrical conductivity, and/or the color of light it reflects. For example, silver generally does not alter the color of the reflected light. Gold, copper, or other colored reflective materials can affect the color of the light and can accordingly be selected to produce a desired color for the light emitted by the SSE202. The conductive, reflective material220acan be deposited directly on the first semiconductor material204, or a transparent electrically conductive material221(shown in broken lines) can be disposed between the first semiconductor material204and the reflective material220a.The transparent electrically-conductive material221can be indium tin oxide (ITO) or any other suitable material that is transparent, electrically conductive, and adheres or bonds the reflective material220ato the first semiconductor material204. The transparent, electrically conductive material221and the reflective material220acan be deposited using CVD, PVD, ALD, plating, or other techniques known in the semiconductor fabrication arts. The transparent, electrically conductive material221and/or the reflective material220acan accordingly form a conductive structure222adjacent to (e.g., in contact with) the SSE202

FIG.3Billustrates an embodiment of a support substrate230being bonded or otherwise attached to the SSE202. The support substrate230can include an optional backside reflective material220b.The backside reflective material220bis bonded or otherwise attached to the reflective material220ausing an elevated pressure and/or elevated temperature process.

FIG.3Cshows an embodiment in which the bonded reflective materials220a,220b(FIG.3B) form a combined reflective material220. The epitaxial growth substrate210has also been thinned, e.g., by backgrinding. At this point, the remaining epitaxial growth substrate210can be implanted with a p-type dopant (e.g., boron) to form a p-n junction with the underlying silicon or other semiconductor material216. In another embodiment, the substrate210can be doped in a prior step. In either embodiment, because the semiconductor material216typically includes buffer layers to facilitate forming the SSE202, and because the buffer layers typically include undoped, large-bandgap semiconductor layers (e.g., GaN, AlGaN or AlN), the p-n junction will be electrically isolated from the epitaxial junction that forms the SSE202.

FIG.3Dillustrates the microelectronic substrate300after (a) the epitaxial growth substrate210has been background and/or etched, (b) the substrate300has been inverted, and (c) the epitaxial growth substrate210has been doped. Most of the semiconductor material216and the epitaxial growth substrate210has been removed using grinding, etching, and/or other processes to expose an outer surface209of the second semiconductor material208or other portions of the SSE202. A portion of the semiconductor material216and the epitaxial growth substrate210remain on the SSE202to form the electrostatic discharge device250. This is one manner in which the electrostatic discharge device250can be made integral with the SSE202and the substrate300. In further embodiments, the same or similar techniques can be used to form multiple electrostatic discharge devices250integral with the SSE202e.g., after the surface209has been selectively etched or otherwise treated.

FIG.3Eillustrates the microelectronic substrate300after a via240has been formed through the electrostatic discharge device250and a portion of the SSE202. The via240can be formed by drilling, etching, or other techniques known in the semiconductor fabrication arts. The via240includes sidewalls241and provides access to the reflective material220which is in electrical communication with the first semiconductor material204, in other embodiments, the via240provides access to the conductive material221, which is in direct electrical contact with the first semiconductor material204.FIG.3Fshows the microelectronic substrate300after a first insulator242has been deposited or formed in the via240and a second insulator244has been deposited or formed on a lateral sidewall243of the electrostatic discharge device250.

FIG.3Gshows the microelectronic substrate300after a conductive material has been disposed in the via240(inward of the first insulator242), and outside the via240to form the first contact246. The first contact246can comprise silver (Ag), gold (Au), gold-tin (AuSn), silver-tin (AgSn), copper (Cu), aluminum (Al), and/or other conductive materials. The first contact246is insulated from the semiconductor material216and the SSE202by the first insulator242. The second contact248has been deposited or otherwise disposed or formed on the outer surface209of the SSE202and on the epitaxial growth substrate210of the electrostatic discharge device250. The second insulator244insulates the second contact248from the semiconductor material216.

In selected embodiments, a lens (not shown inFIG.3G) can be formed over the SSE202. The lens can include a light-transmissive material made from silicone, polymethylmethacryl ate (PMMA), resin, or other materials with suitable properties for transmitting the radiation emitted by the SSE202. The lens can be positioned over the SSE202such that light emitted by the SSE202and reflected by the reflective material220passes through the lens. The lens can include various optical features, such as a curved shape, to diffract or otherwise change the direction of light emitted by the SSE202as it exits the lens.

Embodiments of the integral electrostatic discharge device250offer several advantages over traditional systems. For example, because in particular embodiments the electrostatic discharge device250is comprised of materials (e.g., the epitaxial growth substrate210and the semiconductor material216) that are also used to form the SSE202, the material cost can be less than that of separately-formed electrostatic devices. Moreover, traditional systems having a separate electrostatic discharge die require additional pick-and-place steps to place the die proximate to the SSE202. Still further, such traditional systems require forming additional and/or separate electrical connections to connect the electrostatic device to the SSE.

FIG.4is a cross-sectional view of an SST device400having an electrostatic discharge device450configured in accordance with further embodiments of the present technology. The SST device400can have several features generally similar to those described above with reference toFIGS.2-3G. For example, the SST device400can include an SSE202that in turn includes a first semiconductor material204(e.g., a P-type material), a second semiconductor material208(e.g., an N-type material), and an active region206between the first and second semiconductor materials204,208. The SST device400can further include a reflective material220between the support substrate230and the SSE202. Typically, the SSE202and the reflective/conductive material220are formed on an epitaxial growth substrate210(shown in dashed lines inFIG.4). The structures that form the electrostatic discharge device450and that electrically connect the electrostatic discharge device450to the SSE can be formed on the SSE202while the SSE202is supported by the epitaxial growth substrate210. The epitaxial growth substrate210can then be removed.

In the illustrated embodiment, the electrostatic discharge device450is fabricated on the SSE202, and both the SSE202and the electrostatic discharge device450are carried by the substrate230, with the electrostatic discharge device450positioned between the substrate230and the SSE202. Typically, the fabrication steps for forming the electrostatic discharge device450are performed while the SSE202is inverted from the orientation shown inFIG.4, and before the substrate230is attached. The electrostatic discharge device450can include a plurality of electrostatic junctions460(identified individually as first-third junctions460a-460c). Each electrostatic junction460can include a first conductive material454(identified individually by reference numbers454a-454c), an intermediate material456(identified individually by reference numbers456a-456c), and a second conductive material458(identified individually by reference numbers458a-458c). The materials can be disposed using any of a variety of suitable deposition, masking, and/or etching processes. These materials can be different than the materials forming the SSE202because they are not required to perform a light emitting function. As noted above and as will be understood by one of ordinary skill in the art, these techniques can be used to sequentially form the illustrated layers on the SSE202while the SST device400is inverted relative to the orientation shown inFIG.4. One or more insulating materials461electrically isolates the layers from the first semiconductor material204and/or from the support substrate230.

The intermediate material456can have electrical properties different than those of the first conductive material454and the second conductive material458. In some embodiments, the intermediate material456can be a semiconductor (e.g., amorphous silicon) or a metal. The first conductive material454aof one junction (e.g., the first junction460a) is electrically coupled to the second conductive material458bof an adjacent junction (e.g., the second junction460b). While the illustrated electrostatic discharge device450includes three junctions460placed in series, in further embodiments more or fewer junctions460can be used. Furthermore, to obtain different current-handling capacities for the electrostatic discharge device450, the junctions460can be altered in size, and/or multiple junctions460can be arranged in parallel.

The electrostatic discharge device450can further include a first contact448positioned at a first via449and electrically connected between one of the junctions460(e.g., to the first metal layer454cof the third junction460c), and to the second semiconductor material208. The electrostatic discharge device450additionally includes a second contact446positioned at a second via440extending through the electrostatic discharge device450. The second contact446electrically couples a junction460(e.g., the second metal layer458aof the first junction460a) to the reflective material220or, in further embodiments, to a separate conductive layer or to the first semiconductor material204. The substrate230can be conductive so as to route current to the second contact446. An insulating material461electrically isolates the first and second contacts446,448from adjacent structures.

In some embodiments, components of the electrostatic discharge device450are deposited on the SSE202by PVD, ALD, plating, or other techniques known in the semiconductor fabrication arts. The first and second vias449and440can be formed in the electrostatic discharge device450and/or the SSE202using he methods described above with reference toFIG.3E. In a representative embodiment, the electrostatic discharge device450is formed on the SSE202before the substrate230is attached. In sonic embodiments, the electrostatic discharge device450can be attached to the substrate and/or the SSE202by means of bonding layers. In still further embodiments, the electrostatic discharge device450can be positioned on a portion of an external surface of the SSE202without the substrate230.

FIGS.5A and5Bare cross-sectional views of the SST device400ofFIG.4during operation in accordance with embodiments of the technology. During normal operation, as illustrated inFIG.5A, current flows in the direction of the arrows from the second contact446to the first semiconductor material204, through the SSE202to the second semiconductor material208as described above, to the first contact448. As illustrated inFIG.5B, during an electrostatic discharge event, the SST device400can be protected from reverse currents by providing a path for reverse current flow, illustrated by the arrows, through the junctions460. The reverse current can be directed through the substrate230, rather than through the SSE202.

FIG.6is a partially schematic, partial cross-sectional illustration of a system600that includes an SSE202having components generally similar to those described above, including an active region206positioned between a first semiconductor material204and a second semiconductor material208. The SSE202is carried by a support substrate230, and a conductive/reflective material reflects emitted radiation outwardly through the second semiconductor material208. The support substrate230can be conductive and can accordingly function as a first contact646. The SSE202receives power from the first contact646and a second contact648.

The system600can further include a state device695that in turn includes a photosensor650(e.g., a photodiode). The photosensor650can be formed using residual material from the buffer layer216and the epitaxial growth substrate210, in a manner generally similar to that described above with reference toFIGS.2B-3D. In a particular aspect of an embodiment shown inFIG.6, the epitaxial growth substrate210is doped and/or otherwise treated to form a photosensitive state-sensing component611. Representative materials for forming the state-sensing component611include silicon germanium, gallium arsenide and lead sulfide. The state-sensing component611can be coupled to a first state device contact651and a second state device contact652, which are in turn connected to the controller280. An insulating material653provides electrical insulation between the photosensor650and the second contact648. In a further particular aspect of this embodiment, the buffer layer216is transparent, allowing light emitted from the active region206to impinge upon the state-sensing component611. This in turn can activate the state-sensing component611, which in turn transmits a signal to the controller280. Based upon the signal received from the state device695, the controller can direct the power source270to supply, halt, and/or change the power provided to the SSE202. For example, if the state device695identifies a low output level for the SSE202, the controller280can increase the power provided to the SSE202. If the SSE202produces more than enough light, the controller280can reduce the power supplied to the SSE202. If the color, warmth, and/or other characteristic of the light detected by the state device695falls outside a target range, the controller280can control the power provided to the SSE202and/or can vary the power provided to multiple SSEs202that together produce a particular light output.

FIG.7is a partially schematic, partial cross-sectional illustration of a system700that includes a state device795in the form of a photosensor750in accordance with another embodiment. Unlike the arrangement described above with reference toFIG.6, the photosensor750shown inFIG.7is not formed from residual material used to form the SSE202. Instead, the photosensor750can include a state-sensing component711and an electrically conductive, transparent material712(e.g., zinc oxide) disposed between the state-sensing component711and the second semiconductor material208. The state-sensing component711can include amorphous silicon and/or another material that is responsive to light emanating from the active region206and passing through the conductive/transparent material712. The state device795can further include first and second state device contacts751,752that transmit signals to the controller280corresponding to the amount, quality and/or other characteristic of the light received from the active region206. An insulating material753provides electrical insulation between the state device795and the second contact648. Accordingly, the system700(and in particular, the controller280) can direct the operation of the SSE202based upon information received from the state device795.

In both of the embodiments described above with reference toFIGS.6and7, the state device and state-sensing component are positioned so as to receive at least some of the light that would normally be transmitted directly out of the solid state transducer. In particular, the state-sensing devices can be positioned along a line of sight or optical axis between the active region206and the external environment that receives light from the active region206. In other embodiments, the state-sensing device can be buried within or beneath the SSE202of the optical axis in a manner that can reduce or eliminate the potential interference of the state-sensing devices with light or other radiation emitted by the SSE202.FIGS.8A-8Ldescribe a process for forming such devices in accordance with particular embodiments of the disclosed technology.

FIG.8Aillustrates a device800during a particular phase of manufacture at which the device800includes components generally similar to those described above with reference toFIG.3A. Accordingly, the system can include an epitaxial growth substrate210upon which a buffer layer216and an SSE202are fabricated. The SSE202can include an active region206positioned between first and second semiconductor materials204,208. A conductive, reflective material220is positioned to reflect incident light away from these first semiconductor material204and through the active region206and the second semiconductor material208.

The processes described below with reference toFIGS.8B-8Linclude disposing and removing material using any of a variety of suitable techniques, including PVD or CVD (for deposition) and masking/etching for removal. Using these techniques, sequential layers of material are stacked along a common axis to produce the final product. Beginning withFIG.8B, a recess801is formed in the conductive, reflective material220. The recess801allows light to pass from the SSE202to a photosensitive state device formed in and/or in optical communication with the recess801. InFIG.8C, a transparent insulating material802is disposed in the recess801. InFIG.8D, a transparent conductive material712is disposed on the transparent insulating material802within the recess801. As shown inFIG.8E, a portion of the transparent conductive material712is removed, and the space formerly occupied by the removed portion is filled with additional transparent insulating material802. Accordingly, the transparent conductive material712is electrically isolated from the surrounding conductive reflective material220by the transparent insulating material802.

InFIG.8F, an additional layer of transparent insulating material802is disposed over the transparent conductive material712. InFIG.8G, a portion of the transparent insulating material802positioned over the transparent conductive material712is removed and replaced with a state-sensing component811. In a representative embodiment, the state-sensing component811include amorphous silicon, and in other embodiments, the state-sensing component811can include other materials. In any of these embodiments, an additional volume of transparent insulating material802. is disposed on one side of the state-sensing component811, and a first contact material803is disposed on the other side so as to contact the transparent conductive material712.

InFIG.8H, yet a further layer of transparent insulating material802is disposed on the underlying structures. A portion of this layer is removed and filled with additional first contact material803to form an electrical contact with one side of the state-sensing component811via the transparent conductive material712. A second contact material804is disposed in contact with the opposite surface of the state-sensing component811to provide for a complete circuit.

InFIG.8I, a further layer of transparent insulating material802is disposed over the first and second contact materials803,804, and a substrate support830is attached to the insulating material802. The structure is then inverted, as shown inFIG.8Jand the epitaxial growth substrate210and buffer material216shown inFIG.8Iare removed. Accordingly, the second semiconductor material208is now exposed. InFIG.8K, a plurality of vias840(four are shown inFIG.8Kas vias840a-840d) are made through the support substrate230to an extent sufficient to make electrical contact with multiple components within the device800. For example, a first via840amakes contact with the second semiconductor material208(or, as indicated in dashed lines, a transparent conductive layer overlying the second semiconductor material208), a second via840bmakes contact with the conductive, reflective material220, a third via840cmakes contact with the second contact material804, and a fourth via840dmakes contact with the first contact material803. Each of the vias840a-840dis lined with an insulating material805to prevent unwanted electrical contact with other elements in the stack.

FIG.8Lis a partially schematic illustration of the device800after each of the vias840has been filled with a conductive material806. The conductive material806forms first and second contacts846,848, which provide power from the power source270to the SSE202. The conductive material806also forms first and second state device contacts851,852that provide electrical communication with the controller280. As in the case of the embodiments described above with reference toFIGS.6and7, the resulting state device895is stacked along a common axis with the SSE202. Unlike the arrangement described above with reference toFIGS.6and7, the state device895(in the form of a photosensor850) is not in the direct optical path of light or other radiation emitted by the SSE202. In operation, the state-sensing component811receives radiation through the transparent, insulating material802and the transparent conductive material712. Based upon the radiation incident on the state-sensing component811, the photosensor850can send a signal to the controller280which in turn controls the power source270and the SSE202.

Further details of particular embodiments for constructing an SST device generally similar to that described above with reference toFIGS.8A-8Lare included in co-pending U.S. application Ser. No. 13/218,289, titled “Vertical Solid State Transducers Having Backside Terminals and Associated Systems and Methods”, filed on Aug. 25, 2011, and incorporated herein by reference. In other embodiments, the SST devices can be coupled to external devices with contacts having positions, arrangements, and/or manufacturing methodologies different than those expressly described above.

FIG.9is a partially schematic, partially exploded illustration of an SST device900that include a state device995configured to detect thermal characteristics associated with the SSE202. In the illustrated embodiment, the state device995can include an insulating material902positioned between the conductive reflective material220and a state-sensing component911. In a further particular embodiment, the state-sensing component911can include a thermistor material (e.g., a suitable polymer or ceramic) and in other embodiments, the state-sensing component911can include other thermally sensitive materials (e.g., resistive metals). In any of these embodiments, an additional volume of insulting material902can be positioned against the state-sensing component911to “sandwich” the state-sensing component911and electrically insulate the state-sensing component911from the SSE202. First and second state device contacts951,952provide electrical communication with the state-sensing component911. In particular embodiments, the state-sensing component911can include a material strip with a serpentine shape that increases component sensitivity (e.g., increases impedance or resistance change as a function of temperature). In other embodiments, the state-sensing component911can have other shapes. The state device contacts951,952and the SSE contacts can have any of a variety of locations, including those shown inFIG.9. For example, all the contacts can be located at the top of the device, or the state device contacts can be at the top of the device and one or more SSE contacts at the bottom of the device, or all the contacts can be buried (e.g., as shown inFIG.8L). These options apply to the ESD state-sensing components and optical state-sensing components described above with reference toFIGS.2B-8Las well.

In operation, the state-sensing component911can be coupled to a controller generally similar to that described above with reference toFIG.7, and can control the operation of the SSE in a manner based upon thermal inputs. In particular, the state-sensing component911can sense the temperature of the SSE202and/or other components of the SST device900. In response to a high temperature indication, the controller can reduce the power provided to the SST device900to allow the SST device900to cool before it becomes damaged. After the SST device900has cooled (an event also indicated by the state-sensing component911), the controller can increase the power provided to the SST device900. An advantage of the arrangement described above with reference toFIG.9is that the state-sensing component911can provide feedback that reduces high temperature operation of the SSE202. In particular, the feedback can be used to account for reduced SSE output, reduced safe drive current, reduced forward voltage and/or reduced SSE lifetime, all of which are associated with high temperature operation.

One feature of several of the embodiments described above is that the state-sensing component can be formed so as to be integral with the SST and/or the SSE. Embodiments of the integrally formed state devices are not pre-formed structures and accordingly are not attachable to the SST as a unit, or removable from the SST as a unit without damaging or rendering inoperable the SSE. The SSE and the state device can accordingly be formed as a single chip or die, rather than being formed as two separate dies that may be electrically connected together in a single package. For example, the SSE and the state device can both be supported by the same, single support substrate (e.g., the support substrate230). For example, they can be formed from a portion of the same substrate on which the solid state emitter components are formed, as described above with reference toFIGS.2-3G and6. In the embodiments described with reference toFIGS.4,5,7and8A-8L, the same epitaxial growth substrate is not used for both the solid state emitter and the state device, but the components that form the state device can be formed in situ on the solid state emitter. An advantage of the latter approach is that, in at least some embodiments, the state device can be formed so as to be on the side of the solid state emitter opposite from the path of light emitted by the solid state emitter. Accordingly, the presence of the state device does not interfere with the ability of the solid state emitter to emit light or other radiation.

Although the state device can be formed integrally with the SSE or SST, it performs a function different than that of the SSE and, accordingly, includes materials different than those that form the SSE (e.g., different than the first semiconductor material, the second semiconductor material, and the active region in between). This is the case whether the same epitaxial growth substrate used for the solid state emitter is used for the state device, or whether the state device does not use the same epitaxial growth substrate. As a result, the materials and structural arrangement of the state device are not limited to the materials and structural arrangement of the SSE. This enhanced degree of flexibility can allow for smaller state devices and greater state device efficiencies. For example, state devices in the form of photodiodes can include materials that are specifically selected to be thin and/or highly absorptive at the wavelength emitted by the SSE, producing a compact, efficient structure.

From the foregoing, it will be appreciated that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. For example, some of the embodiments described above discuss the state devices as a diode (e.g., an ESD protection diode or a photodiode). In other embodiments, the state device can include a different, non-linear circuit element. In still further embodiments, the state device may be linear e.g., the thermal sensor can be a linear thermal sensor). The electrostatic discharge device can be constructed and connected to protect the SSE from large reverse voltages, as discussed above in particular embodiments. In other embodiments, the electrostatic discharge device can be connected with a forward bias to prevent the SSE from large forward voltages. In still further embodiments, the SSE can be connected to both types of ESDs, to protect against both high forward and high reverse voltages. Additionally, in certain embodiments, there may be more than one state devices for a particular SST device. Furthermore, material choices for the SSE and substrates can vary in different embodiments of the disclosure.

Certain elements of one embodiment may be combined with other embodiments, in addition to or in lieu of the elements of the other embodiments, or may be eliminated. For example, in some embodiments, the disclosed buffer material can be eliminated. In some embodiments, the buffer material can be used to form the SSE, but not the state device. The disclosed state devices can be combined in other embodiments. For example, a single SST device can include any of a variety of combinations of ESD devices, photosensors and/or thermal sensors. Accordingly, the disclosure can encompass other embodiments not expressly shown or described herein.