LED Array and Method of Forming the Same

Abstract

To provide an LED array and a method for forming the same.SOLUTION: A light emitting diode (LED) device can include a metal contact between a first separation area and a second separation area on a first surface of each epitaxial layer. The LED device can include a first side wall and a second side wall on a second surface of the epitaxial layer distal to the first and second separation areas. The LED device can include a wavelength conversion layer on the epitaxial layer between the first side wall and the second side wall.SELECTED DRAWING: Figure 1I

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 608,316, filed on Dec. 20, 2017, European Patent Application No. 18159747.7, filed on Mar. 2, 2018, and U.S. Patent Application No. 16 / 226,288, filed on Dec. 19, 2018, the contents of which are incorporated herein by reference.

Background Art

[0002] Among the currently available most efficient light sources, there are semiconductor light-emitting devices including light-emitting diodes (LEDs), resonant cavity light-emitting diodes (RCLEDs), vertical cavity surface emitting lasers (VCSELs), and edge-emitting lasers. Material systems currently of interest in the manufacture of high-brightness light-emitting devices operable in the visible spectrum include III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also called III-nitride materials.

[0003] Typically, III-nitride light-emitting devices are manufactured by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a substrate of sapphire, silicon carbide, III-nitride or composite material, or other suitable substrate, by metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers, for example doped with silicon, formed on the substrate, one or more light-emitting layers within the active region formed on the one or more n-type layers, and one or more p-type layers, for example doped with magnesium, formed on the active region. Electrical contacts are formed on these n-type and p-type regions.

Summary of the Invention

[0004] The device may include a metal contact between a first isolation region and a second isolation region on a first surface of the epitaxial layer. The device may include a first sidewall and a second sidewall on a second surface of the epitaxial layer distal to the first isolation region and the second isolation region. The device may include a wavelength conversion layer on the epitaxial layer between the first sidewall and the second sidewall.

Brief Description of the Drawings

[0005] A more detailed understanding will be obtained from the following description given by way of example together with the accompanying drawings.

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Embodiments for Carrying Out the Invention

[0006] Examples of a plurality of different optical illumination systems and / or light emitting diode (“LED”) implementations are described in greater detail below with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example can be combined with features found in one or more other examples to achieve further implementations. Accordingly, it is to be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and are not intended to limit the present disclosure in any way. Throughout, like elements are referenced with like reference numerals.

[0007] It is to be understood that, in describing various elements, terms such as first, second, third, etc. may be used herein, but these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and a second element may be referred to as a first element. As used herein, the term “and / or” can include any and all combinations of one or more of the associated listed items.

[0008] It is to be understood that when an element such as a layer, region, or substrate is referred to as being “on” or “extending onto” another element, it may be directly on or extending directly onto the other element, or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “extending directly onto” another element, intervening elements may be absent. It is also to be understood that when an element is referred to as being “connected to” or “coupled to” another element, it may be directly connected or coupled to the other element, and / or connected or coupled to the other element through one or more intervening elements. In contrast, when an element is referred to as being “directly connected to” or “directly coupled to” another element, there are no intervening elements between that element and the other element. It is to be understood that these terms are intended to encompass elements in different orientations in addition to the orientation depicted in the figures.

[0009] Here, relative terms such as, for example, "below", "above", "upper", "lower", "horizontal", or "vertical" may be used to describe the relationship of one element, layer, or region to another when shown in the figures. It is to be understood that these terms are intended to encompass devices in different orientations in addition to the orientation depicted in the figures.

[0010] Among the currently available most efficient light sources, there are semiconductor light-emitting devices (LEDs), or light output emitting devices such as devices that emit light output in, for example, ultraviolet (UV) or infrared (IR). These devices (hereinafter, "LEDs") can include light-emitting diodes, resonant light-emitting diodes, vertical-cavity laser diodes, edge-emitting lasers, or the like. LEDs can be attractive candidates for a number of different applications, for example, due to their small size and lower power requirements. For example, they can be used as light sources (e.g., flash light and camera flash) for portable battery-powered devices such as cameras and mobile phones. They can also be used, for example, for automotive lighting, head-up display (HUD) lighting, horticultural lighting, street lighting, torches for video, general lighting (e.g., lighting of homes, stores, offices, and studios, theater / stage lighting, and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, used as a backlight for displays, and also used in IR spectroscopy. A single LED will provide light that is not brighter than an incandescent light source, and thus, in applications where brighter light is desired or required, multi-junction devices or arrays of LEDs (e.g., monolithic LED arrays, micro-LED arrays, etc.) can be used.

[0011] According to embodiments of the disclosed subject matter, an LED array (e.g., a micro-LED array) may include an array of pixels as shown in FIGS. 1A, 1B, and / or 1C. The LED array may be used in applications that require precise control of, for example, LED array segments. Pixels within the LED array may be individually addressable, addressable in groups / subsets, or not addressable at all. FIG. 1A shows a top view of an LED array 110 having pixels 111. An enlarged view of a 3×3 portion of the LED array 110 is also shown in FIG. 1A. As shown in the 3×3 enlarged view, the LED array 110 may include pixels 111, which may have a width w1 of about 100 μm or less (e.g., 40 μm). Lanes 113 between the pixels may be separated by a width w2 of about 20 μm or less (e.g., 5 μm). The lanes 113 may provide an air gap between the pixels, as shown in FIGS. 1B and 1C and as further disclosed herein, or may include other materials. The distance d1 from the center of one pixel 111 to the center of an adjacent pixel 111 may be about 120 μm or less (e.g., 45 μm). It is understood that the widths and distances provided herein are merely examples, and the actual widths and / or dimensions may vary.

[0012] It is understood that FIGS. 1A, 1B, and 1C show square pixels arranged in a symmetric matrix, but pixels of any shape and arrangement may be applied to the embodiments disclosed herein. For example, the LED array 110 of FIG. 1A may include more than 10,000 pixels in any applicable arrangement, such as, for example, a 100×100 matrix, a 200×50 matrix, a symmetric matrix, an asymmetric matrix, or the like. It is also understood that multiple sets of pixels, matrices, and / or substrates may be arranged in any applicable form to implement the embodiments disclosed herein.

[0013] Figure 1B shows a cross-sectional view of an example of the LED array 1000. As shown, pixels 1010, 1020, and 1030 correspond to three different pixels in the LED array, and the separation part 1041 and / or the n contact 1040 are arranged to separate these pixels from each other. According to one embodiment, the space between the pixels can be occupied by an air gap. As shown, pixel 1010 includes an epitaxial layer 1011, which can be grown on an applicable substrate such as a sapphire substrate that can be removed from the epitaxial layer 1011. The surface of the growth layer distal from the contact 1015 may be substantially planar or may be patterned. The p-type region 1012 can be arranged close to the p-contact 1017. The active region 1021 can be arranged adjacent to the n-type region and the p-type region 1012. Alternatively, the active region 1021 can emit a light beam by being between the semiconductor layer or the n-type region and the p-type region 1012 and receiving current. The p-contact 1017 can contact the SiO2 layers 1013 and 1014 and the plated metal (e.g., plated copper) layer 1016. The n-contact 1040 can include an applicable metal such as Cu. The metal layer 1016 can contact the reflective layer 1015 that can function as a contact.

[0014] In particular, as shown in FIG. 1B, the n-contact 1040 may be deposited in a trench 1130 formed between the pixels 1010, 1020, and 1030 and extend beyond the epitaxial layer 1011. The separation part 1041 may separate all of the wavelength conversion layer 1050 (as shown) or may separate a part thereof. It should be understood that the LED array may be implemented without using such a separation part 1041, or the separation part 1041 may correspond to an air gap. The separation part 1041 may be an extension of the n-contact 1040 such that the separation part 1041 is formed of the same material (for example, copper) as the n-contact 1040. Alternatively, the separation part 1041 may be formed of a material different from that of the n-contact 1040. According to one embodiment, the separation part 1041 may include a reflective material. The material of the separation part 1041 and / or the n-contact 1040 may be deposited by any applicable method, such as applying a mesh structure that includes or enables the deposition of the n-contact 1040 and / or the separation part 1041. The wavelength conversion material 1050 may have characteristics / features similar to those of the wavelength conversion layer 205 in FIG. 2A. As mentioned herein, one or more additional layers may cover the separation part 1041. Such a layer may be a reflective layer, a scattering layer, an absorption layer, or any other applicable layer. One or more passivation layers 1019 may completely or partially separate the n-contact 1040 from the epitaxial layer 1011.

[0015] The epitaxial layer 1011 can be formed from any applicable material that emits photons when excited, including sapphire, SiC, GaN, silicon, and more specifically, but not limited to, group III-V semiconductors including AlN, AlP, AlAs, AlSb, GaN, GaP, GaSb, InN, InP, InAs, InSb, group II-VI semiconductors including but not limited to ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including but not limited to Ge, Si, SiC, or mixtures or alloys thereof. These semiconductor examples can have a refractive index in the range of about 2.4 to about 4.1 at the typical emission wavelengths of the LEDs in which they are present. For example, group III nitride semiconductors such as GaN can have a refractive index of about 2.4 at 500 nm, and group III phosphide semiconductors such as InGaP can have a refractive index of about 3.7 at 600 nm. Contacts coupled to the LED device 200 may be formed from solder, such as, for example, AuSn, AuGa, AuSi, or SAC solder.

[0016] The n-type region can be grown on a growth substrate and can include one or more layers of semiconductor material. The one or more layers can include different compositions and dopant concentrations, including, for example, a preparation layer and / or a layer designed to facilitate removal of the growth substrate. These layers can be n-type, can be intentionally undoped, or can even be p-type device layers. These layers can be designed to meet specific optical, material, or electrical properties that are desirable for the light-emitting region to emit light efficiently. Similarly, the p-type region 1012 can include a plurality of layers of different compositions, thicknesses, and dopant concentrations, and the plurality of layers can include layers that are intentionally undoped or n-type layers. Current can be made to flow through the pn junction (e.g., via contacts), and the pixel can generate light of a first wavelength that is at least partially determined by the bandgap energy of the material. The pixel can emit light directly (e.g., normal emission or direct emission LED), or can emit light into the wavelength conversion layer 1050, and the wavelength conversion layer 1050 can act to further change the wavelength of the emitted light to output light of a second wavelength (e.g., phosphor-converted LED, "PCLED", etc.).

[0017] FIG. 1B shows an example of an LED array 1000 having pixels 1010, 1020, and 1030 of one configuration example, but it is understood that the pixels in the LED array can be provided in any one of several configurations. For example, the pixel can be a flip-chip structure, a vertical injection thin film (VTF) structure, a multi-junction structure, a thin film flip-chip (TFFC), a lateral device, etc. For example, a lateral LED pixel can be similar to a flip-chip LED pixel, but can be not turned upside down for direct connection of electrodes to the substrate or package. The TFFC can also be similar to a flip-chip LED pixel, but the growth substrate can be removed (leaving the thin film semiconductor layer unsupported). In contrast, a flip-chip LED can include a growth substrate or other substrate as part of it.

[0018] The wavelength conversion layer 1050 can be in the path of the light emitted by the active region 1021 such that the light emitted by the active region 1021 can cross one or more intermediate layers (e.g., photonic layers). According to an embodiment, the wavelength conversion layer 1050 may not be present within the LED array 1000. The wavelength conversion layer 1050 can include any luminescent material that absorbs light of one wavelength and emits light of a different wavelength, such as phosphor particles within a transparent or translucent binder or matrix, or a ceramic phosphor element. The thickness of the wavelength conversion layer 1050 can be determined based on the material used, or can be determined based on the application / wavelength for which the LED array 1000 or the individual pixels 1010, 1020, and 1030 are configured. For example, the wavelength conversion layer 1050 can be about 20 μm, 50 μm, or 200 μm. The wavelength conversion layer 1050 can be provided on each of the individual pixels as shown, or can be disposed over the entire LED array 1000.

[0019] The primary optical system 1022 can be on or above one or more of the pixels 1010, 1020, and / or 1030, enabling the light from the active region 1021 and / or the wavelength conversion layer 1050 to pass through the primary optical system. The light passing through the primary optical system can generally be emitted based on a Lambertian distribution pattern, such that the luminous intensity of the light emitted through the primary optical system 1022 is proportional to the cosine of the angle between the direction of the incident light and the surface normal when observed from an ideal diffusing emitter. It is understood that one or more characteristics of the primary optical system 1022 may be modified to generate a light distribution pattern different from the Lambertian distribution pattern.

[0020] A secondary optical system including one or both of the lens 1065 and the waveguide 1062 can be provided at the pixels 1010, 1020, and / or 1030. It is understood that the secondary optical system, which is described for a plurality of pixels according to the example shown in FIG. 1B, may be provided for a single pixel. The secondary optical system can be used to spread the incident light (diverging optical system) or to collect the incident light into a collimated beam (collimating optical system). The waveguide 1062 may be coated with a dielectric material, a metallization layer, or the like, and may be provided to reflect or redirect the incident light. In an alternative embodiment, the illumination system may not include one or more of the wavelength conversion layer 1050, the primary optical system 1022, the waveguide 1062, and the lens 1065.

[0021] The lens 1065 can be formed from any suitable transparent material such as, but not limited to, for example, SiC, aluminum oxide, diamond, or the like, or a combination thereof. The lens 1065 can be used to modify the light beam input to the lens 1065 such that the output beam from the lens 1065 efficiently meets the desired photometric specifications. Further, the lens 1065 can serve one or more aesthetic purposes, such as, for example, by determining the appearance of the lighting and / or non-lighting of the plurality of LED devices 200B.

[0022] FIG. 1C shows a cross-sectional view of the LED array 1100 as seen in three dimensions. As shown, the pixels in the LED array 1100 can be separated by trenches filled to form the n-contacts 1140. The pixels can be grown on the substrate 1114 and can include the p-contact 1113, the p-GaN semiconductor layer 1112, the active region 1111, and the n-GaN semiconductor layer 1110. It is understood that this structure is provided as just an example, and one or more semiconductor layers or other applicable layers may be added, removed, partially added, or partially removed to implement the disclosure provided herein. A converter material 1117 may be deposited on the semiconductor layer 1110 (or other applicable layer).

[0023] As shown, a passivation layer 1115 is formed in trench 1130, and an n-contact 1140 (e.g., a copper contact) can be deposited in trench 1130. The passivation layer 1115 can separate at least a portion of the n-contact 1140 from one or more layers of the semiconductor. According to one implementation, the n-contact 1140 or other applicable material in the trench can extend into the converter material 1117 such that the n-contact 1140 or other applicable material provides complete or partial optical isolation between pixels.

[0024] Manufacturing a small addressable LED pixel system can be costly and difficult. Conventional pick-and-place techniques available for use at millimeter-scale component sizes may be unsuitable for sub-100 micron components that need to be positioned with micron accuracy. Forming a continuous GaN layer for an LED pixel system can create stresses that cause wafer curvature. It may be desirable to form a device without a thick continuous GaN layer to suppress wafer curvature and to enable easier high temperature annealing. Providing wafer-scale electrical connections to selectively grown GaN mesas is described in more detail below.

[0025] The following description may include sub-100 μm to 300 μm pixels that may include a plurality of GaN mesas that are selectively grown (SAG) and / or etched. These mesas may be partially or completely electrically isolated from each other. By reducing the thickness and / or total number of continuous GaN layers, integrated film stress and wafer curvature can be reduced when forming a multi-section LED in a matrix layout. Further, higher temperature annealing can be used, particularly in sections of highly strained epitaxial layers, to provide specific electrical and optical properties for multi-wavelength emission. The SAG GaN material can be formed on a sapphire substrate and later the sapphire substrate can be removed to reduce optical loss due to the lateral waveguide effect. The SAG GaN material exposed after removal of the sapphire substrate can be used for phosphor encapsulation.

[0026] Next, referring to FIG. 1D, a cross-sectional view is shown that illustrates forming a trench 122 in a sapphire substrate 120. The sapphire substrate 120 can be made of a crystalline material such as, for example, aluminum oxide and can be a commercially available sapphire wafer. The sapphire substrate 120 can be etched, patterned, or grooved using conventional patterning and etching techniques to form the trench 122. In one example, the trench 122 can be formed using wet etching. In another example, the trench 122 may be formed by dry etching techniques such as, for example, reactive ion etching (RIE) and inductively coupled plasma reactive ion etching (ICP-RIE). Note that although the trench is shown as triangular in shape in FIG. 1D, it can take any desired shape formed by the etching process. The sapphire substrate 120 can be similar to the substrate 1114 described above with reference to FIG. 1C and can be formed using similar techniques.

[0027] Next, referring to FIG. 1E, a cross-sectional view showing the formation of a first semiconductor layer 126 within trench 122 is shown. The first semiconductor layer 126 may be composed of one or more materials optimized for lattice matching and coefficient of thermal expansion matching between the sapphire substrate 120 and subsequent semiconductor layers. The first semiconductor layer 126 may be composed of a semiconductor material, a metal oxide, a metal nitride, or a combination of a metal and a semiconductor material. Examples of materials that may be used for the first semiconductor layer 126 include, but are not limited to, SiC, Al2O1, GaN, AlN, and AlGaN. The first semiconductor layer 126 may be doped with an n-type dopant such as Si or a p-type dopant such as Mg. The concentration of the dopant in the first semiconductor layer 126 may not have a significant impact on the refractive index of the first semiconductor layer 126, but an excessive dopant concentration may distort the crystal structure of the first semiconductor layer 126. This may adversely affect the quality of subsequent semiconductor layers grown on the first semiconductor layer 126. In one example, the first semiconductor layer 126 may be doped with Si to a nominal and constant concentration from 3e18 cm -3 to 5e19 cm -3 . Also, the first semiconductor layer 126 may have a graded dopant concentration.

[0028] The first semiconductor layer 126 may be formed using conventional deposition techniques such as, for example, metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. In an epitaxial deposition process, the reactants supplied by one or more source gases are controlled, and system parameters are set such that the atoms that attach reach the deposition surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms on the deposition surface. The temperature at which the first semiconductor layer 126 is grown may affect the surface morphology of the semiconductor layer grown on the nucleation layer. The first semiconductor layer 126 may be grown and / or annealed at a high temperature, such as, for example, between 900 °C and 1200 °C. In another example, the first semiconductor layer 126 may be grown between 1080 °C and 1165 °C.

[0029] The thickness, composition, dopant concentration, and film formation temperature of the first semiconductor layer 126 can each be selected such that the first semiconductor layer 126 promotes light extraction of the device by having a refractive index close to that of the subsequent semiconductor layer and produces favorable surface characteristics for the subsequent semiconductor layer.

[0030] The first semiconductor layer 126 can be made of any III-V semiconductor, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also known as group-III nitride materials. For example, the first semiconductor layer 126 can be a III-V semiconductor including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb; a II-VI semiconductor including, but not limited to, ZnS, ZnSe, CdSe, CdTe; a group-IV semiconductor including, but not limited to, Ge, Si, SiC; or a mixture or alloy thereof. These semiconductors can have a refractive index in the range of about 2.4 to about 4.1 at the typical emission wavelength of the LEDs in which they are present. For example, a group-III nitride semiconductor such as GaN can have a refractive index of about 2.4 at 500 nm, and a group-III phosphide semiconductor such as InGaP can have a refractive index of about 3.7 at 600 nm. In one example, the first semiconductor layer 126 can be made of GaN.

[0031] The first semiconductor layer 126 can be formed using conventional deposition techniques such as, for example, MOCVD, MBE, or other epitaxial techniques. The first semiconductor layer 126 can be doped with an n-type dopant.

[0032] Next, referring to FIG. 1F, a cross-sectional view is shown illustrating the formation of an active region 128 and a second semiconductor layer 130 on a first semiconductor layer 126. The second semiconductor layer 130 and the active region 128 can be made of any III-V semiconductor, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also known as group III nitride materials. For example, the second semiconductor layer 130 and the active region 128 can be made of III-V semiconductors including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb; II-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe; IV group semiconductors including, but not limited to, Ge, Si, SiC; or mixtures or alloys thereof. These semiconductors can have a refractive index in the range of about 2.4 to about 4.1 at the typical emission wavelengths of the LEDs in which they are present. For example, a group III nitride semiconductor such as GaN can have a refractive index of about 2.4 at 500 nm, and a group III phosphide semiconductor such as InGaP can have a refractive index of about 3.7 at 600 nm. In one example, the second semiconductor layer 130 and the active region 128 can be made of GaN.

[0033] The second semiconductor layer 130 and the active region 128 can be formed using conventional deposition techniques such as, for example, MOCVD, MBE, or other epitaxial techniques. The active region 128 and the second semiconductor layer 130 can be formed together with the first semiconductor layer 126, or alternatively, can be formed separately. The active region 128 and the second semiconductor layer 130 can be composed of the same semiconductor material as the first semiconductor layer 126, or their compositions can be different.

[0034] The second semiconductor layer 130 can be doped with a p-type dopant. Accordingly, the active region 128 can be a pn diode junction associated with the interface between the first semiconductor layer 126 and the second semiconductor layer 130. Alternatively, the active region 128 may include one or more semiconductor layers that are n-type doped, p-type doped, or undoped. The active region 128 can emit light upon application of an appropriate voltage through the first semiconductor layer 126 and the second semiconductor layer 130. In an alternative implementation, the conductivity types of the first semiconductor layer 126 and the second semiconductor layer 130 may be reversed. That is, the first semiconductor layer 126 may be a p-type layer and the second semiconductor layer 130 may be an n-type layer. The first semiconductor layer 126, the active region 128, and the second semiconductor layer 130 may collectively be referred to as the epitaxial layer 180. The epitaxial layer 180 may be similar to the epitaxial layer 1011 described above with reference to FIG. 1B and may be formed using similar techniques.

[0035] Next, referring to FIG. 1G, a cross-sectional view is shown illustrating the formation of an isolation region 132 and a metal contact 134 on the second semiconductor layer 130. The isolation region 132 may be made of a dielectric material such as, for example, an oxide, a nitride, or an oxynitride. The isolation region 132 may be formed using conventional deposition techniques such as, for example, CVD, plasma enhanced chemical vapor deposition (PECVD), MOCVD, atomic layer deposition (ALD), evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other similar processes. The isolation region 132 may be patterned and etched using conventional techniques. The metal contact 134 may be composed of one or more layers of a conductive metal or metal alloy such as, for example, gold, silver, copper. The metal contact 134 may be formed using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, plating, spin-on deposition, or other similar processes. The metal contact 134 may be patterned and etched using conventional techniques. The isolation region 132 may be formed to be located above the first semiconductor layer 126 formed within the trench 122. The isolation region 132 may define the pixel 111 described above with reference to FIG. 1A.

[0036] Next, referring to FIG. 1H, a cross-sectional view showing the removal of the sapphire substrate 120 is shown. The sapphire substrate 120 can be removed by a conventional process such as grinding, chemical mechanical polishing (CMP), or laser lift-off. In one example, the sapphire substrate 120 can be selectively removed with respect to the first semiconductor layer 126 and the first semiconductor layer 126. Removal of the sapphire substrate 120 can expose the bottom surface 136 of the first semiconductor layer 126 and one or more sidewalls 140 consisting of the first semiconductor layer 126. The one or more sidewalls 140 may be referred to as one or more protrusions. The one or more sidewalls 140 of the first semiconductor layer 126 can extend below the bottom surface 136 of the first semiconductor layer 126. Removing the sapphire substrate 120 can form a well 138 bounded by the bottom surface 136 of the first semiconductor layer 126 and the one or more sidewalls 140. In one example, the bottom surface 136 can be roughened after it is exposed.

[0037] Next, referring to FIG. 1I, a cross-sectional view showing the formation of the wavelength conversion layer 142 in the well 138 is shown. The wavelength conversion layer 142 can be formed on the bottom surface 136 of the first semiconductor layer 126 between the sidewalls 140.

[0038] The wavelength conversion layer 142 can be composed of an elemental phosphor or its compound. The wavelength conversion layer 142 can be formed using conventional deposition techniques such as, for example, CVD, plasma enhanced chemical vapor deposition (PECVD), MOCVD, atomic layer deposition (ALD), evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other similar processes. The wavelength conversion layer 142 can include one or more phosphors. A phosphor is a luminescent material that can absorb excitation energy (usually radiant energy) and emit the absorbed energy as radiation of energy different from the original excitation energy. The phosphor can have a quantum efficiency close to 100%, which means that almost all photons provided as excitation energy can be re-emitted by the phosphor. The phosphor can also be highly absorptive. Since the light-emitting active region 128 can directly emit light to the highly efficient and highly absorptive wavelength conversion layer 142, the phosphor can efficiently extract light from the device. The phosphors used in the wavelength conversion layer 142 can include, but are not limited to, any conventional green, yellow, and red-emitting phosphors.

[0039] The wavelength conversion layer 142 can be formed by depositing phosphor particles on the bottom surface 136 of the first semiconductor layer 126. The phosphor particles can be in direct contact with the first semiconductor layer 126 such that the light emitted from the active region 128 can be directly coupled to the phosphor particles. Although not shown in FIG. 1I, a light coupling medium may be provided to hold the phosphor particles in place. The light coupling medium can be selected to have a refractive index as close as possible without significantly exceeding the refractive index of the first semiconductor layer 126. For the most efficient operation, it can be assumed that there is no lossy medium between the first semiconductor layer 126, the phosphor particles of the wavelength conversion layer 142, and the light coupling medium.

[0040] The phosphor particles can have a particle size between 0.1 μm and 20 μm. To form the wavelength conversion layer 142, the phosphor particles can be applied, for example, by electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques. In techniques such as spin coating or spray coating, the phosphor is disposed in a slurry having an organic binder, and after deposition of the slurry, the organic binder can be evaporated, for example, by heating. Then, optionally, an optical coupling medium can be applied. The phosphor particles can be nanoparticles themselves (i.e., particles in the size range of 100 nm to 1000 nm). Spherical phosphor particles typically produced by spray pyrolysis or other methods can be applied to produce a layer with a high packing density that provides advantageous scattering characteristics. Also, the phosphor particles can be coated with a material having a larger bandgap than the light emitted by the phosphor, such as SiO2, Al2O3, MePO4, or polyphosphoric acid, or other suitable metal oxides.

[0041] The wavelength conversion layer 142 can be a ceramic phosphor rather than a phosphor powder. The ceramic phosphor can be formed by heating the powder phosphor at high pressure until the surface of the phosphor particles softens and begins to melt. The partially melted particles can adhere to each other to form a hard aggregate of particles. To form a polycrystalline ceramic layer, an uniaxial or isostatic pressing step and vacuum sintering of a preformed "green body" may be required. By adjusting the heating or pressure conditions, the manufacturing method, the phosphor particle precursor used, and the appropriate crystal lattice of the phosphor material, the light transmissivity of the ceramic phosphor (i.e., the amount of scattering it produces) can be controlled from high opacity to high transparency. For example, in addition to the phosphor, other ceramic forming materials such as alumina may be included to facilitate the formation of the ceramic or to adjust the refractive index of the ceramic.

[0042] The wavelength conversion layer 142 may be composed of a mixture of silicone and phosphor particles. In this example, the wavelength conversion layer 142 can be diced from a plate and disposed on the bottom surface 136 of the first semiconductor layer 126.

[0043] In another example, a PSS substrate having a pattern of pre-formed raised regions and recessed regions can be used to form SAG and etched GaN mesas. In yet another example, after forming the first semiconductor layer 126 in the trench 122, the first semiconductor layer 126 can be planarized to expose the upper surface of the sapphire substrate 120 and then the first semiconductor layer 126 can be formed. Accordingly, the first semiconductor layer 126 can be directly formed on the first semiconductor layer 126 and on the upper surface of the sapphire substrate 120. When the sapphire substrate 120 is removed, the wavelength conversion layer 142 can be directly formed on the lower surface of the first semiconductor layer 126 and bounded by the sidewalls 140 of the first semiconductor layer 126.

[0044] As shown in FIG. 1B, one or more n-contacts 1040 can be formed on the sidewall 137 of the epitaxial layer 180 and extend to one or more sidewalls 140. One or more passivation layers 1019 can completely or partially separate one or more n-contacts 1040 from the epitaxial layer 180 and one or more sidewalls 140.

[0045] Next, referring to FIG. 1J, a cross-sectional view showing the formation of the first semiconductor layer 148 on the PSS substrate 144 is shown. The PSS substrate 144 can be made of a crystalline material such as aluminum oxide, for example, and can be a commercially available sapphire wafer. The PSS substrate 144 can be etched, patterned, or grooved using conventional patterning and etching techniques. The recessed regions of the PSS substrate 144 can be formed by dry etching techniques such as RIE and ICP-RIE, for example. The PSS substrate 144 can be made the same as the substrate 1114 described above with reference to FIG. 1C and can be formed using similar techniques.

[0046] The first semiconductor layer 148 can be formed in the recess of the PSS substrate 144. The first semiconductor layer 148 can be made of one or more materials optimized for lattice matching and coefficient of thermal expansion matching between the PSS substrate 144 and subsequent semiconductor layers. The first semiconductor layer 148 can be composed of a semiconductor material, a metal oxide, a metal nitride, or a combination of a metal and a semiconductor material. Examples of materials that can be used for the first semiconductor layer 148 include, but are not limited to, SiC, Al2O1, GaN, AlN, and AlGaN. The first semiconductor layer 148 can be doped with an n-type dopant such as Si or a p-type dopant such as Mg. The concentration of the dopant in the first semiconductor layer 148 may not have a significant impact on the refractive index of the first semiconductor layer 148, but an excessive dopant concentration can distort the crystal structure of the first semiconductor layer 148. This can have an adverse effect on the quality of the subsequent semiconductor layer grown on the first semiconductor layer 148. In one example, the first semiconductor layer 148 can be doped with Si to a nominal and constant concentration from 3e18cm -3 to 5e19cm -3 . Also, the first semiconductor layer 148 may have a graded dopant concentration.

[0047] The first semiconductor layer 148 can be formed using conventional deposition techniques such as, for example, MOCVD, MBE, or other epitaxial techniques. In an epitaxial deposition process, the reactants supplied by one or more source gases are controlled, and the system parameters are set so that the atoms that adhere reach the deposition surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms on the deposition surface. The temperature at which the first semiconductor layer 148 is grown can affect the surface morphology of the semiconductor layer grown on the nucleation layer. The first semiconductor layer 148 can be grown and / or annealed at a high temperature, such as, for example, between 900 °C and 1200 °C. In another example, the first semiconductor layer 148 can be grown between 1080 °C and 1165 °C.

[0048] The thickness, composition, dopant concentration, and film formation temperature of the first semiconductor layer 148 can each be selected such that the first semiconductor layer 148 promotes light extraction of the device by having a refractive index close to that of the subsequent semiconductor layer and produces favorable surface characteristics for the subsequent semiconductor layer.

[0049] The first semiconductor layer 148 can be made of any III-V semiconductor, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also known as III-nitride materials. For example, the first semiconductor layer 148 can be a III-V semiconductor including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb; a II-VI semiconductor including, but not limited to, ZnS, ZnSe, CdSe, CdTe; a IV semiconductor including, but not limited to, Ge, Si, SiC; or a mixture or alloy thereof. These semiconductors can have refractive indices in the range of about 2.4 to about 4.1 at the typical emission wavelengths of the LEDs in which they are present. For example, a III-nitride semiconductor such as GaN can have a refractive index of about 2.4 at 500 nm, and a III-phosphide semiconductor such as InGaP can have a refractive index of about 3.7 at 600 nm. In one example, the first semiconductor layer 148 can be made of GaN.

[0050] The first semiconductor layer 148 can be formed using conventional deposition techniques such as, for example, MOCVD, MBE, or other epitaxial techniques. The first semiconductor layer 148 can be doped with an n-type dopant.

[0051] Next, referring to FIG. 1K, a cross-sectional view is shown that illustrates forming a separation region 150 on the upper surface 152 of the first semiconductor layer 148. The separation region 150 can be made of a dielectric material such as, for example, oxide, nitride, or oxynitride. The separation region 150 can be formed using conventional deposition techniques such as, for example, CVD, plasma enhanced chemical vapor deposition (PECVD), MOCVD, atomic layer deposition (ALD), evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other similar processes. The separation region 150 can be patterned and etched using conventional techniques. The separation region 150 can be formed such that a portion of the upper surface 152 of the first semiconductor layer 148 is exposed within the opening 154. Prior to the deposition of the separation region 150, a first contact 172 can be formed within the first semiconductor layer 148. The first contact 172 can be formed by etching a trench within the first semiconductor layer 148 and filling it with one or more layers of a conductive metal or metal alloy such as, for example, gold, silver, copper. The first contact 172 can be formed using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, plating, spin-on deposition, or other similar processes.

[0052] Next, referring to FIG. 1L, a cross-sectional view is shown that illustrates forming a mesa 156 on the first semiconductor layer 148 and on the separation region 150. The mesa 156 can be formed such that a first portion 158 of the mesa 156 contacts the upper surface 152 of the first semiconductor layer 148, a second portion 160 of the mesa 156 contacts the sidewall of the separation region 150, and a third portion 162 of the mesa 156 contacts the upper surface of the separation region 150.

[0053] The mesa 156 can be made of any III-V semiconductor, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also known as III-nitride materials. For example, the mesa 156 can be made of III-V semiconductors including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb; II-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe; IV semiconductors including, but not limited to, Ge, Si, SiC; or mixtures or alloys thereof. These semiconductors can have a refractive index in the range of about 2.4 to about 4.1 at the typical emission wavelengths of the LEDs in which they are present. For example, III-nitride semiconductors such as GaN can have a refractive index of about 2.4 at 500 nm, and III-phosphide semiconductors such as InGaP can have a refractive index of about 3.7 at 600 nm. In one example, the mesa 156 can be made of GaN.

[0054] The mesa 156 can be formed using conventional deposition techniques such as, for example, MOCVD, MBE, or other epitaxial techniques. The mesa 156 may be formed together with the first semiconductor layer 148 and the active region so as to form the epitaxial layer 1011 described above with reference to FIG. 1B, or may be formed separately. The mesa 156 may be composed of a semiconductor material similar to that of the first semiconductor layer 148, or their compositions may be different.

[0055] Next, referring to FIG. 1M, a cross-sectional view showing the formation of the second semiconductor layer 164 on the mesa 156 is shown. The second semiconductor layer 164 can be selectively grown on the mesa 156 using conventional deposition processes such as, for example, MOCVD, MBE, or other epitaxial techniques.

[0056] The second semiconductor layer 164 can be made of any III-V semiconductor, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also known as group III nitride materials. For example, the second semiconductor layer 164 can be a III-V semiconductor including, but not limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, a II-VI semiconductor including, but not limited to, ZnS, ZnSe, CdSe, CdTe, a group IV semiconductor including, but not limited to, Ge, Si, SiC, or a mixture or alloy thereof. These semiconductors can have a refractive index in the range of about 2.4 to about 4.1 at the typical emission wavelength of the LED in which they are present. For example, a group III nitride semiconductor such as GaN can have a refractive index of about 2.4 at 500 nm, and a group III phosphide semiconductor such as InGaP can have a refractive index of about 3.7 at 600 nm. In one example, the second semiconductor layer 164 can be made of AlGaN.

[0057] The second semiconductor layer 164 may be formed together with the mesa 156 or may be formed separately. The mesa 156 and the second semiconductor layer 164 may be composed of the same semiconductor material as the first semiconductor material 148, or their compositions may be different.

[0058] The mesa 156 and the second semiconductor layer 164 can be doped with a p-type dopant, and the first semiconductor layer 148 can be doped with an n-type dopant. Accordingly, a part of the mesa 156 can act as an active region. This active region can be a pn diode junction associated with the interface between the first semiconductor layer 148 and the mesa 156. Alternatively, the first semiconductor layer 148 and the mesa 156 can be doped with an n-type dopant, and the second semiconductor layer 164 can be doped with a p-type dopant. Accordingly, a part of the mesa 156 can act as an active region. This active region can be a pn diode junction associated with the interface between the mesa 156 and the second semiconductor layer 164. The active region within the mesa 156 may include one or more semiconductor layers that are n-type doped, p-type doped, or undoped.

[0059] The active region can emit light upon application of an appropriate voltage through the first semiconductor layer 148 and / or the second semiconductor layer 164. In an alternative implementation, the conductivity types of the first semiconductor layer 148, the mesa 156, and the second semiconductor layer 164 may be reversed.

[0060] After the second semiconductor layer 164 is formed, the device can be processed in several ways to form the top-side electrical connection.

[0061] Referring now to FIGS. 1N-1O, a cross-sectional view showing an example of forming a top-side electrical connection on the structure of FIG. 1M is shown. FIG. 1N shows forming a dielectric layer 166 on the second semiconductor layer 164. The dielectric layer 166 can be made of a dielectric material such as, for example, an oxide, a nitride, or an oxynitride. The dielectric layer 166 can be formed on the second semiconductor layer 164 using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other similar processes. The isolation region 150 can be patterned and etched using conventional techniques. In one example, the dielectric layer 166 is also formed on the isolation region 150 and can be removed using conventional patterning and etching techniques. FIG. 1O shows removing a portion of the dielectric layer 166 to expose the upper surface 168 of the second semiconductor layer 164. The exposed upper surface 168 of the second semiconductor layer 164 can act as a contact. In one example, the second semiconductor layer 164 can be made of a p-type material and the upper surface 168 can act as a p-type contact.

[0062] Next, referring to FIG. 1P, a cross-sectional view is shown illustrating the formation of a metal contact layer 170 on mesa 156 to form one or more pixels 111. The metal contact layer 170 may be formed on the dielectric layer 166 and on the second semiconductor layer 164. The metal contact layer 170 may be composed of one or more layers of a conductive metal or metal alloy such as gold, silver, copper, etc. The metal contact layer 170 may be formed using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, plating, spin-on deposition, or other similar processes. The metal contact layer 170 may be patterned and etched using conventional techniques. The metal contact layer 170 may act as an anode contact and a reflective layer. In one example, an air bridge may be used to form a contact within the first semiconductor layer.

[0063] Next, referring to FIG. 1Q, a cross-sectional view is shown illustrating the formation of a second contact 175 through the isolation region 150. The second contact 175 may be formed by etching a trench through the isolation region 150 and a portion of the first semiconductor layer 148 and filling it with one or more layers of a conductive metal or metal alloy such as gold, silver, copper, etc. The second contact 175 may be formed using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, plating, spin-on deposition, or other similar processes. The second contact 175 may be similar to the n-contact 1040 described above with reference to FIG. 1B. A passivation layer 177 may be formed between the second contact 175 and the metal contact layer 170. Although one second contact 175 is shown, two or more second contacts 175 may be formed within one or more isolation regions 150. Note that the second contact 175 may be formed using the above-described process in any of the embodiments described herein.

[0064] Next, referring to FIG. 1R, a cross-sectional view showing the removal of the PSS substrate 144 is shown. The PSS substrate 144 can be removed by a conventional process such as grinding, chemical mechanical polishing (CMP), or laser lift-off.

[0065] In another example, the PSS substrate can be removed to expose the back surface of the device, and a common contact can be formed. Next, referring to FIG. 1S, a cross-sectional view showing the removal of the PSS substrate 144 to form the common contact layer 174 is shown. The PSS substrate 144 can be removed by a conventional process such as grinding, chemical mechanical polishing (CMP), or laser lift-off. The removal of the PSS substrate 144 can expose the bottom surface 176 of the first semiconductor layer 148. In one example, the bottom surface 176 can be roughened after it is exposed.

[0066] The common contact layer 174 can be formed on the bottom surface 176 of the first semiconductor layer 148. The common contact layer 174 can be composed of a blanket transparent conductor. In one example, the common contact layer 174 can be composed of a transparent conductive oxide (TCO) such as indium tin oxide (ITO). The common contact layer 174 can be a p-contact or an n-contact. The common contact layer 174 can be formed using a conventional deposition technique such as CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other similar processes. Since the PSS substrate 144 has been removed, a phosphor (not shown) can be directly attached onto the common contact layer 174 to form the LED emitter 102.

[0067] Next, referring to FIG. 1T, a cross-sectional view showing another example of forming a top-side electrical connection to the structure of FIG. 1M is shown. FIG. 1T shows forming a metal contact layer 178 on the second semiconductor layer 164. The metal contact layer 170 can be formed on the dielectric layer 166 and on the second semiconductor layer 164. The metal contact layer 178 can be composed of one or more layers of a conductive metal or metal alloy such as gold, silver, copper, etc. The metal contact layer 178 can be formed using conventional deposition techniques such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, plating, spin-on deposition, or other similar processes. The metal contact layer 178 can be patterned and etched using conventional techniques.

[0068] Next, referring to FIG. 1U, a cross-sectional view showing removing the PSS substrate 144 is shown. The PSS substrate 144 can be removed by conventional processes such as, for example, grinding, chemical mechanical polishing (CMP), or laser lift-off.

[0069] An epitaxial layer can be formed on the sapphire substrate. The sapphire substrate can have one or more trenches in which the epitaxial layer is grown.

[0070] Next, referring to FIG. 1V, a flowchart showing a method of forming a device is shown. At step 192, a metal contact can be formed between a first isolation region and a second isolation region on a first surface of an epitaxial layer. At step 194, a wavelength conversion layer can be formed on a second surface of the epitaxial layer between a first sidewall and a second sidewall. The first surface can be distal to the second surface. The first sidewall and the second sidewall can be portions of the epitaxial layer formed in trenches etched into a sapphire substrate. Note that the term "distal", as used herein, can be used as a directional term meaning the spatially opposite side of an element, device, layer, or other structure. A first element and a second element on opposite distal sides of a third element can be separated from each other by at least a portion of the third element. For example, the upper surface of a layer can be distal to the lower surface of that layer.

[0071] FIG. 2A is a top view of an electronics substrate with an LED array 410 attached to the substrate in an LED device attachment region 318 in one embodiment. This electronics substrate represents an LED system 400A together with the LED array 410. Also, a power module 312 receives a voltage input at Vin497, receives a control signal from a connection and control module 316 on trace 418B, and provides a drive signal to the LED array 410 on trace 418A. The LED array 410 is turned on and off by a drive signal from the power module 312. In the embodiment shown in FIG. 2A, the connection and control module 316 receives a sensor signal from the sensor module 314 on trace 418C.

[0072] Figure 2B shows an embodiment of a two-channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board 499. As shown in Figure 2B, the LED lighting system 400B includes a first surface 445A having an input for receiving a dimmer signal and an AC power signal, on which an AC / DC converter circuit 412 is mounted. The LED system 400B includes a second surface 445B, on which a connection and control module 416 (a wireless module in this example) having a dimmer interface circuit 415, DC-DC converter circuits 440A and 440B, a microcontroller 472, and an LED array 410 are mounted. The LED array 410 is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to provide a drive signal to the LED array, or any number of multiple channels may be used to provide a drive signal to the LED array.

[0073] The LED array 410 may include two groups of LED devices. In one example embodiment, the LED devices of group A are electrically coupled to the first channel 411A, and the LED devices of group B are electrically coupled to the second channel 411B. Each of the two DC-DC converters 440A and 440B may provide a respective drive current through a single channel 411A and 411B to drive the LEDs of group A and group B within the LED array 410, respectively. One group of LEDs among these LED groups may be configured to emit light having a different color point from the LEDs of the second LED group. By controlling the current and / or duty cycle provided by the individual DC / DC converter circuits 440A and 440B through the single channels 411A and 411B, respectively, the composite color point of the light emitted by the LED array 410 can be adjusted within a certain range. The embodiment shown in Figure 2B does not include the sensor module (described in Figure 2A), but an alternative embodiment may include a sensor module.

[0074] The illustrated LED lighting system 400B is an integrated system in which an LED array 410 and a circuit for operating the LED array 410 are provided on a single electronics substrate. Connections between modules on the same surface of the circuit board 499 can be electrically coupled by on - surface or under - surface interconnects or metallizations (not shown), such as traces 431, 432, 433, 434, and 435, for example, to exchange, for example, voltage, current, and control signals between the modules. Connections between modules on the opposite surface of the circuit board 499 can be electrically coupled by through - substrate interconnects, such as vias and metallizations (not shown).

[0075] According to an embodiment, an LED system may be provided in which the LED array is on an electronics substrate separate from the driver circuit and the control circuit. According to other embodiments, an LED system may have the LED array as part of an electronic circuit on an electronics substrate separate from the driver circuit. For example, an LED system may include an LED module and a power conversion module placed on an electronics substrate separate from the LED array.

[0076] According to an embodiment, the LED system may include a multi - channel LED driver circuit. For example, the LED module may include embedded LED calibration / setting data and, for example, three groups of LEDs. As will be recognized by those skilled in the art, any number of groups of LEDs may be used in harmony with one or more applications. The individual LEDs within each group may be configured in series or in parallel, and light having different color points may be provided. For example, warm white light may be provided by a first group of LEDs, cool white light may be provided by a second group of LEDs, and intermediate white light may be provided by a third group.

[0077] Figure 2C shows an example of a vehicle headlamp system 300 that includes a vehicle power supply 302 and includes a data bus 304. A sensor module 307 may be connected to the data bus 304 to provide data regarding environmental conditions (e.g., ambient light conditions, temperature, time, rain, fog, etc.), vehicle conditions (parked, in motion, speed, direction), the presence / position of other vehicles, pedestrians, objects, or the like. The sensor module 307 may be the same as or similar to the sensor module 314 of Figure 2A. An AC / DC converter 305 may be connected to the vehicle power supply 302.

[0078] The AC / DC converter 312 of Figure 2C can be the same as or similar to the AC / DC converter 412 of Figure 2B and can receive AC power from the vehicle power supply 302. It can convert the AC power to DC power, as described in Figure 2B with respect to the AC-DC converter 412. The vehicle headlamp system 300 can include active headlamps 330 that receive one or more inputs provided by or based on the AC / DC converter 305, the connection and control module 306, and / or the sensor module 307. As an example, the sensor module 307 can detect the presence of a pedestrian. If a pedestrian is not sufficiently illuminated, it reduces the driver's likelihood of seeing the pedestrian. Based on such sensor input, the connection and control module 306 can use the power supplied from the AC / DC converter 305 to output data to the active headlamps 330 such that the output data activates a subset of the LEDs within the LED array housed within the active headlamps 330. When activated, the subset of LEDs within the LED array can emit light in the direction in which the sensor module 307 sensed the presence of the pedestrian. After the sensor module 307 provides updated data confirming that there are no longer pedestrians in the path of the vehicle including the vehicle headlamp system, these subsets of LEDs can be deactivated, or their light beam directions can be changed otherwise.

[0079] Figure 3 shows an example of a system 550 that includes an application platform 560, LED systems 552 and 556, and optical systems 554 and 558. The LED system 552 generates an optical beam 561 shown between arrows 561a and 561b. The LED system 556 may generate an optical beam 562 between arrows 562a and 562b. In the embodiment shown in Figure 3, the light emitted from the LED system 552 passes through the secondary optical system 554, and the light emitted from the LED system 556 passes through the secondary optical system 554. In an alternative embodiment, the optical beams 561 and 562 do not pass through any secondary optical system. The secondary optical system can be or can include one or more optical guides. The one or more optical guides may be of the edge-lit type or may have an internal aperture that defines an internal edge of the optical guide. The LED systems 552 and / or 556 can be inserted into the internal apertures of the one or more optical guides to inject light into the internal edges (internally apertured optical guides) of the one or more optical guides, or can inject light into the external edges (edge-lit optical guides). The LEDs within the LED systems 552 and / or 556 may be arranged surrounding a base that is part of the optical guide. According to one implementation, the base can be thermally conductive. According to one implementation, the base can be coupled to a heat dissipation element disposed on the optical guide. The heat dissipation element can be configured to receive the heat generated by the LEDs via the thermally conductive base and dissipate the received heat. The one or more optical guides can enable the light emitted by the LED systems 552 and 556 to be shaped as desired, such as, for example, in a gradient, chamfered distribution, narrow distribution, wide distribution, angular distribution, or the like.

[0080] In an example embodiment, the system 550 can be a camera flash system for a mobile phone, indoor residential or commercial lighting, outdoor lighting such as streetlights, automobiles, medical devices, AR / VR devices, and robotic devices. The LED system 400A shown in Figure 2A and the vehicle headlamp system 300 shown in Figure 2C illustrate the LED systems 552 and 556 in an example embodiment.

[0081] The application platform 560 can supply power to the LED systems 552 and / or 556 via a power bus through line 565 or other applicable inputs, as described herein. Further, the application platform 560 can provide an input signal through line 565 for the operation of the LED system 552 and the LED system 556, and this input can be based on user input / preferences, sensed readings, outputs that are pre-programmed or autonomously determined, or the like. One or more sensors may be inside or outside the housing of the application platform 560. Alternatively or in addition, as shown in the LED system 400 of FIG. 2A, each of the LED systems 552 and 556 can include its own sensor module, connection and control module, power module, and / or LED device.

[0082] In an embodiment, sensors of the application platform 560, and / or sensors of the LED systems 552 and / or 556 may collect data such as, for example, visual data (e.g., LIDAR data, IR data, data collected via a camera, etc.), audio data, distance-based data, movement data, environmental data, or the like, or combinations thereof. The data may be related to physical items or entities such as, for example, objects, individuals, vehicles, etc. For example, a sensing device may collect object proximity data for an ADAS / AV-based application, which may prioritize detection and subsequent actions based on the detection of physical items or entities. The data may be collected, for example, by emitting an optical signal such as an IR signal by the LED systems 552 and / or 556 and collecting data based on the emitted optical signal. The data may be collected by a component different from the component that emits the optical signal for data collection. Continuing with this example, a sensing device may be disposed on a vehicle, which may emit a beam using a vertical cavity surface emitting laser (VCSEL). One or more sensors may sense a response to the emitted beam or other applicable input.

[0083] In an example embodiment, the application platform 560 may represent an automobile, and the LED systems 552 and 556 may represent automobile headlights. In various embodiments, the system 550 may represent an automobile with steerable light beams that selectively activate a plurality of LEDs to provide steerable light. For example, an array of LEDs may be used to define or project a shape or pattern, or to illuminate only a selected portion of a road. In one example embodiment, an infrared camera or detector pixel within the LED system 552 and / or 556 may serve as a sensor (e.g., similar to the sensor module 314 of FIG. 2A and the sensor module 307 of FIG. 2C) that identifies portions of a scene (such as a road, a crosswalk, etc.) that require illumination.

[0084] Although the embodiments have been described in detail, those skilled in the art will understand that the embodiments described herein can be modified without departing from the spirit of the inventive concept given this specification. Accordingly, there is no intention that the scope of the invention be limited to the specific embodiments illustrated and described.

Claims

1. A first semiconductor layer, an active region on the first semiconductor layer, and a second semiconductor layer on the active region, a trench extending from a first surface of the second semiconductor layer, through the active region, and at least partially through the first semiconductor layer to separate a plurality of light-emitting regions, a first metal contact extending from the first surface of the second semiconductor layer to the first semiconductor layer and electrically connected to a sidewall of the first semiconductor layer, a second metal contact to the second semiconductor layer, a passivation layer insulating the first metal contact from the second semiconductor layer, the active region, and the second metal contact, a wavelength conversion layer on a second surface of the first semiconductor layer distal from the first surface, having, wherein the trench completely penetrates the first semiconductor layer and extends into the wavelength conversion layer, the first metal contact forms a first protrusion and a second protrusion on the second surface of the first semiconductor layer, and the wavelength conversion layer is between the first protrusion and the second protrusion, a light-emitting diode device.

2. The light-emitting diode device according to claim 1, wherein the first metal contact is an n-contact.

3. The light-emitting diode device according to claim 1, wherein the second metal contact is a p-contact.

4. The light-emitting diode device according to claim 1, wherein the first semiconductor layer has an n-type doped group III nitride, and the second semiconductor layer has a p-type doped group III nitride.

5. The light-emitting diode device according to claim 1, wherein the active region has a partially doped or undoped group III nitride.

6. The light-emitting diode device according to claim 1, further comprising at least one dielectric layer on the second metal contact.

7. The light-emitting diode device according to claim 6, further comprising a metal layer on the at least one dielectric layer.

8. The light-emitting diode device according to claim 7, further comprising a reflective layer on the metal layer.

9. The light-emitting diode device according to claim 8, wherein the reflective layer is a contact.

10. A plurality of pixels, each pixel separated from adjacent pixels by a trench extending from a p-type semiconductor layer to a distal surface of an n-type semiconductor layer. the n-contact within the trench, the n-type semiconductor layer disposed on the active layer on the p-type semiconductor layer, the wavelength conversion layer on the n-type semiconductor layer on the surface opposite to the active layer, the p-contact on the p-type semiconductor layer, one or more passivation layers extending from the p-type semiconductor layer to the n-type semiconductor layer and separating the n-contact from the active layer and the p-type semiconductor layer, and one or more passivation layers at least partially extending on the sidewalls of the n-type semiconductor layer, having, at least a part of the wavelength conversion layer is separated by the n-contact within the trench, LED array.

11. The LED array according to claim 10, wherein the n-contact within the trench forms a protrusion that separates the wavelength conversion layer on each pixel.

12. The LED array according to claim 10, wherein the active layer has a partially doped or undoped group III nitride.

13. The LED array according to claim 10, wherein the n-contact extends to the wavelength conversion layer and provides at least partial optical insulation between each pixel.

14. The LED array according to claim 10, wherein the n-type semiconductor layer and the p-type semiconductor layer are not continuous between the plurality of pixels.

15. A plurality of pixels, each pixel being separated from an adjacent pixel by a trench extending from the p-type semiconductor layer to the distal surface of the n-type semiconductor layer, a plurality of pixels, the n-contact within the trench, the n-type semiconductor layer disposed on the active layer on the p-type semiconductor layer, the wavelength conversion layer on the n-type semiconductor layer on the surface opposite to the active layer, the p-contact on the p-type semiconductor layer, one or more passivation layers extending from the p-type semiconductor layer to the n-type semiconductor layer and separating the n-contact from the active layer and the p-type semiconductor layer, and one or more passivation layers at least partially extending on the sidewalls of the n-type semiconductor layer, having, the n-contact extends to the wavelength conversion layer and provides at least partial optical insulation between each pixel, LED array.

16. The LED array according to claim 15, wherein at least a part of the wavelength conversion layer is separated by the n-contact within the trench.

17. The LED array according to claim 16, wherein the n contacts in the trench form protrusions that separate the wavelength conversion layer on each pixel. **Claim 18** The LED array according to claim 15, wherein the active layer has a group III nitride that is partially doped or undoped. **Claim 19** The LED array according to claim 15, wherein the n-type semiconductor layer and the p-type semiconductor layer are not continuous between the plurality of pixels.

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