Patent Publication Number: US-2019189682-A1

Title: Monolithic segmented led array architecture with transparent common n-contact

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/608,307 filed on Dec. 20, 2017 and EP Patent Application No. 18159072.0 filed on Feb. 28, 2018, the contents of which are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     Semiconductor light-emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently available. Materials systems currently of interest in the manufacture of high-brightness light emitting devices capable of operation across the visible spectrum include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. 
     Typically, III-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a sapphire, silicon carbide, III-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers doped with, for example, silicon, formed over the substrate, one or more light emitting layers in an active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, magnesium, formed over the active region. Electrical contacts are formed on the n- and p-type regions. 
     SUMMARY 
     A device may include an isolation region in an epitaxial layer. The isolation region may have a width that is at least a width of a trench formed in a p-type contact layer and a reflective layer on the epitaxial layer. 
     A light emitting diode (LED) array may include an epitaxial layer having a first pixel and a second pixel separated by an isolation region. A reflective layer may be formed on the epitaxial layer. A p-type contact layer may be formed on the reflective layer. The isolation region may have a width that is at least a width of a trench formed in a p-type contact layer. 
     A method of forming a device may include forming a trench in a p-type contact layer and a reflective layer to expose an epitaxial layer. An isolation region may be formed in the epitaxial layer exposed by the trench using ion implantation. The isolation region may separate a first pixel and a second pixel and having a width that is at least a width of the trench. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
         FIG. 1A  is a top view illustration of an LED array with an exploded portion; 
         FIG. 1B  is a cross sectional illustration of an LED array with trenches; 
         FIG. 1C  is a perspective illustration of another LED array with trenches; 
         FIG. 1D  is a cross section view of an epitaxial layer formed on a sapphire substrate; 
         FIG. 1E  is a cross section view illustrating forming a reflective layer on the epitaxial layer; 
         FIG. 1F  is a cross section view illustrating forming a resist layer on the reflective layer; 
         FIG. 1G  is a cross section view illustrating patterning the resist layer to form one or more trenches; 
         FIG. 1H  is a cross section view illustrating removing portions of the reflective layer exposed by the one or more trenches; 
         FIG. 1I  is a cross section view illustrating forming isolation regions within the epitaxial layer; 
         FIG. 1J  is a cross section view illustrating another example of forming isolation regions within the epitaxial layer; 
         FIG. 1K  is a cross section view illustrating another example of forming isolation regions within the epitaxial layer; 
         FIG. 1L  is a cross section view illustrating removing the resist layer; 
         FIG. 1M  is a cross section view illustrating forming a p-type contact layer on the reflective layer; 
         FIG. 1N  is a cross section view illustrating removing the sapphire substrate; 
         FIG. 1O  is a cross section view illustrating forming a common n-contact layer on a bottom surface of the epitaxial layer; 
         FIG. 1P  is a cross section view of a reflective layer formed on an epitaxial layer; 
         FIG. 1Q  is a cross section view illustrating removing portions of the reflective layer  1  and the epitaxial layer; 
         FIG. 1R  is a cross section view of forming a dielectric layer  152  and an n-type contact; 
         FIG. 1S  is a cross section view of a LED array formed on a sapphire substrate; 
         FIG. 1T  illustrates removing the sapphire substrate from the epitaxial layer; 
         FIG. 1U  illustrates forming walls on the lower surface of the epitaxial layer; 
         FIG. 1V  illustrates forming a wavelength converting layer within wells formed by the walls; 
         FIG. 1W  illustrates removing portions of the sapphire substrate from the epitaxial layer; 
         FIG. 1X  illustrates forming a wavelength converting layer within the wells; 
         FIG. 1Y  illustrates a cross section view of a LED array formed on a sapphire substrate; 
         FIG. 1Z  illustrates removing the sapphire substrate; 
         FIG. 1AA  illustrates forming a wavelength converting layer within the wells; 
         FIG. 1AB  illustrates a cross section view of a LED array formed on a sapphire substrate; 
         FIG. 1AC  illustrates removing the sapphire substrate; 
         FIG. 1AD  illustrates forming a wavelength converting layer within the wells; 
         FIG. 1AE  is a flowchart illustrating a method of forming a device; 
         FIG. 2A  is a top view of the electronics board with LED array attached to the substrate at the LED device attach region in one embodiment; 
         FIG. 2B  is a diagram of one embodiment of a two channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board; 
         FIG. 2C  is an example vehicle headlamp system; and 
         FIG. 3  shows an example illumination system. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of different light illumination systems and/or light emitting diode (“LED”) implementations will be described more fully hereinafter with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and they are not intended to limit the disclosure in any way. Like numbers refer to like elements throughout. 
     It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element may be termed a second element and a second element may be termed a first element without departing from the scope of the present invention. As used herein, the term “and/or” may include any and all combinations of one or more of the associated listed items. 
     It will 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 extend 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, there may be no intervening elements present. It will also be understood that when an element is referred to as being “connected” 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 via one or more intervening elements. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures. 
     Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. 
     Semiconductor light emitting devices (LEDs) or optical power emitting devices, such as devices that emit ultraviolet (UV) or infrared (IR) optical power, are among the most efficient light sources currently available. These devices (hereinafter “LEDs”), may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. Due to their compact size and lower power requirements, for example, LEDs may be attractive candidates for many different applications. For example, they may be used as light sources (e.g., flash lights and camera flashes) for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for automotive lighting, heads up display (HUD) lighting, horticultural lighting, street lighting, torch for video, general illumination (e.g., home, shop, office and studio lighting, theater/stage lighting and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, as back lights for displays, and IR spectroscopy. A single LED may provide light that is less bright than an incandescent light source, and, therefore, multi-junction devices or arrays of LEDs (such as monolithic LED arrays, micro LED arrays, etc.) may be used for applications where more brightness is desired or required. 
     According to embodiments of the disclosed subject matter, LED arrays (e.g., micro LED arrays) may include an array of pixels as shown in  FIG. 1A, 1B , and/or  1 C. LED arrays may be used for any applications such as those requiring precision control of LED array segments. Pixels in an LED array may be individually addressable, may be addressable in groups/subsets, or may not be addressable. In  FIG. 1A , a top view of a LED array  110  with pixels  111  is shown. An exploded view of a 3×3 portion of the LED array  110  is also shown in  FIG. 1A . As shown in the 3×3 portion exploded view, LED array  110  may include pixels  111  with a width w 1  of approximately 100 μm or less (e.g., 40 μm). The lanes  113  between the pixels may be separated by a width, w 2 , of approximately 20 μm or less (e.g., 5 μm). The lanes  113  may provide an air gap between pixels or may contain other material, as shown in  FIGS. 1B and 10  and further disclosed herein. The distance d 1  from the center of one pixel  111  to the center of an adjacent pixel  111  may be approximately 120 μm or less (e.g., 45 μm). It will be understood that the widths and distances provided herein are examples only, and that actual widths and/or dimensions may vary. 
     It will be understood that although rectangular pixels arranged in a symmetric matrix are shown in  FIGS. 1A , B and C, pixels of any shape and arrangement may be applied to the embodiments disclosed herein. For example, LED array  110  of  FIG. 1A  may include, over 10,000 pixels in any applicable arrangement such as a 100×100 matrix, a 200×50 matrix, a symmetric matrix, a non-symmetric matrix, or the like. It will also be understood that multiple sets of pixels, matrixes, and/or boards may be arranged in any applicable format to implement the embodiments disclosed herein. 
       FIG. 1B  shows a cross section view of an example LED array  1000 . As shown, the pixels  1010 ,  1020 , and  1030  correspond to three different pixels within an LED array such that a separation sections  1041  and/or n-type contacts  1040  separate the pixels from each other. According to an embodiment, the space between pixels may be occupied by an air gap. As shown, pixel  1010  includes an epitaxial layer  1011  which may be grown on any applicable substrate such as, for example, a sapphire substrate, which may be removed from the epitaxial layer  1011 . A surface of the growth layer distal from contact  1015  may be substantially planar or may be patterned. A p-type region  1012  may be located in proximity to a p-contact  1017 . An active region  1021  may be disposed adjacent to the n-type region and a p-type region  1012 . Alternatively, the active region  1021  may be between a semiconductor layer or n-type region and p-type region  1012  and may receive a current such that the active region  1021  emits light beams. The p-contact  1017  may be in contact with SiO2 layers  1013  and  1014  as well as plated metal (e.g., plated copper) layer  1016 . The n type contacts  1040  may include an applicable metal such as Cu. The metal layer  1016  may be in contact with a reflective layer  1015  which may serve as a contact. 
     Notably, as shown in  FIG. 1B , the n-type contact  1040  may be deposited into trenches  1130  created between pixels  1010 ,  1020 , and  1030  and may extend beyond the epitaxial layer. Separation sections  1041  may separate all (as shown) or part of a converter material  1050 . It will be understood that a LED array may be implemented without such separation sections  1041  or the separation sections  1041  may correspond to an air gap. The separation sections  1041  may be an extension of the n-type contacts  1040 , such that, separation sections  1041  are formed from the same material as the n-type contacts  1040  (e.g., copper). Alternatively, the separation sections  1041  may be formed from a material different than the n-type contacts  1040 . According to an embodiment, separation sections  1041  may include reflective material. The material in separation sections  1041  and/or the n-type contact  1040  may be deposited in any applicable manner such as, for example, but applying a mesh structure which includes or allows the deposition of the n-type contact  1040  and/or separation sections  1041 . Converter material  1050  may have features/properties similar to wavelength converting layer  205  of  FIG. 2A . As noted herein, one or more additional layers may coat the separation sections  1041 . Such a layer may be a reflective layer, a scattering layer, an absorptive layer, or any other applicable layer. One or more passivation layers  1019  may fully or partially separate the n-contact  1040  from the epitaxial layer  1011 . 
     The epitaxial layer  1011  may be formed from any applicable material to emit photons when excited including sapphire, SiC, GaN, Silicone and may more specifically be formed from a 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, group IV semiconductors including, but not limited to Ge, Si, SiC, and mixtures or alloys thereof. These example semiconductors may have indices of refraction ranging from about 2.4 to about 4.1 at the typical emission wavelengths of LEDs in which they are present. For example, III-Nitride semiconductors, such as GaN, may have refractive indices of about 2.4 at 500 nm, and III-Phosphide semiconductors, such as InGaP, may have refractive indices of about 3.7 at 600 nm. Contacts coupled to the LED device  200  may be formed from a solder, such as AuSn, AuGa, AuSi or SAC solders. 
     The n-type region may be grown on a growth substrate and may include one or more layers of semiconductor material that include different compositions and dopant concentrations including, for example, preparation layers, such as buffer or nucleation layers, and/or layers designed to facilitate removal of the growth substrate. These layers may be n-type or not intentionally doped, or may even be p-type device layers. The layers may be designed for particular optical, material, or electrical properties desirable for the light emitting region to efficiently emit light. Similarly, the p-type region  1012  may include multiple layers of different composition, thickness, and dopant concentrations, including layers that are not intentionally doped, or n-type layers. An electrical current may be caused to flow through the p-n junction (e.g., via contacts) and the pixels may generate light of a first wavelength determined at least in part by the bandgap energy of the materials. A pixel may directly emit light (e.g., regular or direct emission LED) or may emit light into a wavelength converting layer  1050  (e.g., phosphor converted LED, “POLED”, etc.) that acts to further modify wavelength of the emitted light to output a light of a second wavelength. 
     Although  FIG. 1B  shows an example LED array  1000  with pixels  1010 ,  1020 , and  1030  in an example arrangement, it will be understood that pixels in an LED array may be provided in any one of a number of arrangements. For example, the pixels may be in a flip chip structure, a vertical injection thin film (VTF) structure, a multi-junction structure, a thin film flip chip (TFFC), lateral devices, etc. For example, a lateral LED pixel may be similar to a flip chip LED pixel but may not be flipped upside down for direct connection of the electrodes to a substrate or package. A TFFC may also be similar to a flip chip LED pixel but may have the growth substrate removed (leaving the thin film semiconductor layers un-supported). In contrast, the growth substrate or other substrate may be included as part of a flip chip LED. 
     The wavelength converting layer  1050  may be in the path of light emitted by active region  1021 , such that the light emitted by active region  1021  may traverse through one or more intermediate layers (e.g., a photonic layer). According to embodiments, wavelength converting layer  1050  or may not be present in LED array  1000 . The wavelength converting layer  1050  may include any luminescent material, such as, for example, phosphor particles in a transparent or translucent binder or matrix, or a ceramic phosphor element, which absorbs light of one wavelength and emits light of a different wavelength. The thickness of a wavelength converting layer  1050  may be determined based on the material used or application/wavelength for which the LED array  1000  or individual pixels  1010 ,  1020 , and  1030  is/are arranged. For example, a wavelength converting layer  1050  may be approximately 20 μm, 50 μm or 200 μm. The wavelength converting layer  1050  may be provided on each individual pixel, as shown, or may be placed over an entire LED array  1000 . 
     Primary optic  1022  may be on or over one or more pixels  1010 ,  1020 , and/or  1030  and may allow light to pass from the active region  101  and/or the wavelength converting layer  1050  through the primary optic. Light via the primary optic may generally be emitted based on a Lambertian distribution pattern such that the luminous intensity of the light emitted via the primary optic  1022 , when observed from an ideal diffuse radiator, is directly proportional to the cosine of the angle between the direction of the incident light and the surface normal. It will be understood that one or more properties of the primary optic  1022  may be modified to produce a light distribution pattern that is different than the Lambertian distribution pattern. 
     Secondary optics which include one or both of the lens  1065  and waveguide  1062  may be provided with pixels  1010 ,  1020 , and/or  1030 . It will be understood that although secondary optics are discussed in accordance with the example shown in  FIG. 1B  with multiple pixels, secondary optics may be provided for single pixels. Secondary optics may be used to spread the incoming light (diverging optics), or to gather incoming light into a collimated beam (collimating optics). The waveguide  1062  may be coated with a dielectric material, a metallization layer, or the like and may be provided to reflect or redirect incident light. In alternative embodiments, a lighting system may not include one or more of the following: the wavelength converting layer  1050 , the primary optics  1022 , the waveguide  1062  and the lens  1065 . 
     Lens  1065  may be formed form any applicable transparent material such as, but not limited to SiC, aluminum oxide, diamond, or the like or a combination thereof. Lens  1065  may be used to modify the a beam of light to be input into the lens  1065  such that an output beam from the lens  1065  will efficiently meet a desired photometric specification. Additionally, lens  1065  may serve one or more aesthetic purpose, such as by determining a lit and/or unlit appearance of the multiple LED devices  200 B. 
       FIG. 1C  shows a cross section of a three dimensional view of a LED array  1100 . As shown, pixels in the LED array  1100  may be separated by trenches which are filled to form n-contacts  1140 . The pixels may be grown on a substrate  1114  and may include a p-contact  1113 , a p-GaN semiconductor layer  1112 , an active region  1111 , and an n-Gan semiconductor layer  1110 . It will be understood that this structure is provided as an example only and one or more semiconductor or other applicable layers may be added, removed, or partially added or removed to implement the disclosure provided herein. A converter material  1117  may be deposited on the semiconductor layer  1110  (or other applicable layer). 
     Passivation layers  1115  may be formed within the trenches  1130  and n-contacts  1140  (e.g., copper contacts) may be deposited within the trenches  1130 , as shown. The passivation layers  1115  may separate at least a portion of the n-contacts  1140  from one or more layers of the semiconductor. According to an implementation, the n-contacts  1140 , or other applicable material, within the trenches may extend into the converter material  1117  such that the n-contacts  1140 , or other applicable material, provide complete or partial optical isolation between the pixels. 
     One approach for electrical isolation may include selective ion implants. For example, ions may be implanted in a pattern that defines an implanted perimeter around an LED die. With sufficient doping, the implanted ions may be highly resistive and may isolate or define a junction of the implanted perimeter. One approach for providing electrical connections may include transparent conductors. For example, transparent conductors may be used in a conventional, non-monolithic LED structure that sandwiches a light active material with transparent conductors such as indium tin oxide (ITO). 
     Monolithic segmented LEDs constructed using etched gallium nitride (GaN) mesas is feasible, but has substantial associated processing costs. Elimination of the etched mesa would reduce edge losses and provide for a more mechanically sound device. The following description includes methods of using selective ion implantation and transparent conductors to form monolithic segmented LEDs without the need for etched individual mesas. Apparatuses described herein may include sub-100 μm to 300 μm pixels separated by electrically non-conductive lanes having a width less than approximately 50 μm. The electrical isolation between pixels on a monolithic substrate may be provided by ion implantation into a GaN layer. A common n-contact for the pixels may be provided by a transparent conductor layer. A sapphire substrate may be removed to reduce lateral light transfer. 
     Referring now to  FIG. 1D , a cross section view of an epitaxial layer  122  formed on a sapphire substrate  120  is shown. The sapphire substrate  120  may compose a crystalline material, such as aluminum oxide, and may be a commercial sapphire wafer. The epitaxial layer  122  may compose any Group III-V semiconductors, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. In an example, the epitaxial layer  122  may compose GaN. The epitaxial layer  122  may be formed using conventional deposition techniques, such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. In an epitaxial deposition process, chemical reactants provided by one or more source gases are controlled and the system parameters are set so that depositing atoms arrive at a deposition surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms of the deposition surface. Accordingly, the epitaxial layer  122  may be grown on the sapphire substrate  120  using conventional epitaxial techniques. 
     The epitaxial layer  122  may be similar to the epitaxial layer  1011  described above with reference to  FIG. 1B  and may be formed using similar techniques. As described above, the epitaxial layer may include an active region  127  between a first semiconductor layer and a second semiconductor layer. The active region  127  may be composed of any Group III-V semiconductors, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. For example, the active region  127  may be composed of III-V semiconductors including but not limited to AN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductors including but not limited to ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including but not limited to Ge, Si, SiC, and mixtures or alloys thereof. These semiconductors may have indices of refraction ranging from about 2.4 to about 4.1 at the typical emission wavelengths of LEDs in which they are present. For example, III-nitride semiconductors, such as GaN, may have refractive indices of about 2.4 at 500 nm, and III-phosphide semiconductors, such as InGaP, may have refractive indices of about 3.7 at 600 nm. In an example, the second semiconductor layer  130  and the active region  128  may be composed of GaN. 
     Referring now to  FIG. 1E , a cross section view illustrating forming a reflective layer  124  on the epitaxial layer  122  is shown. The reflective layer  124  may compose any material that reflects visible light, such as, for example, a refractive metal. The reflective layer  124  may compose one or more of a metal such as silver, gold, and titanium oxide, a metal stack, a dielectric material, or combinations thereof. The reflective layer  124  may be formed using a conventional deposition technique, such as, for example, chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. 
     Referring now to  FIG. 1F , a cross section view illustrating forming a resist layer  126  on the reflective layer  124  is shown. The resist layer  126  may compose a conventional photoresist material based on photoacid accelerators, such as, for example, a negative tone or a positive tone resist. A positive tone resist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes soluble to the photoresist developer. The portion of the photoresist that is unexposed remains insoluble to the photoresist developer. A negative tone resist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes insoluble to the photoresist developer. The unexposed portion of the photoresist is dissolved by the photoresist developer. The resist layer  126  may compose a conventional x-ray resist material. The resist layer  126  may include an anti-reflection coating (ARC) layer (not shown) first deposited on the reflective layer  124 . The ARC layer may compose a conventional ARC material. 
     Referring now to  FIG. 1G , a cross section view illustrating patterning the resist layer  126  to form one or more trenches  128  is shown. The resist layer  126  may be masked and exposed to an energy source to remove a portion of the resist layer  126  and form the one or more trenches  128 . A patterning mask with an opaque region and a transparent region may be formed on the resist layer  126  and may be illuminated by the energy source. The energy source may pass through the transparent region. In a positive tone photoresist, this may cause the exposed portion of the resist layer  126  to be chemically changed or modified such that it may be dissolved and removed when the resist layer  126  is exposed to a developer solution. Alternatively in a negative tone photoresist, the energy adsorption may result in chemical changes in the exposed portion of the resist layer  126  that cause it to be insoluble to a developer. The energy source may include light, such as, for example, visible light, ultra-violet light, or deep ultra-violet light. The energy source may include amplified light, such as, for example a laser. In yet another embodiment, the energy source may include x-rays. Once the portions of the resist layer  126  are removed, one or more trenches  128  may be formed. The portions of the resist layer  126  may be removed selective to the reflective layer  124 . The one or more trenches  128  may expose an upper surface of the reflective layer  124 . 
     Referring now to  FIG. 1H , a cross section view illustrating removing portions of the reflective layer  124  exposed by the one or more trenches  128  is shown. The portions of the reflective layer  124  may be removed selective to the resist layer  126  and the epitaxial layer  122 . The portions of the reflective layer  124  may be removed using a conventional etching process, such as, for example, wet etching, plasma etching, and reactive ion etching (RIE). Removing the portions of the reflective layer  124  from the one or more trenches  128  may expose an upper surface  130  of the epitaxial layer  122 . 
     Referring now to  FIG. 11 , a cross section view illustrating forming isolation regions  132  within the epitaxial layer  122  is shown. The isolation regions  132  may be formed by introducing dopant atoms below the upper surface  130  of the epitaxial layer  122 . In an example, the dopant atoms may be introduced through a conventional ion implantation process. The dopant atoms may be implanted in an ion implantation step through the one or more trenches  128  through the active region  127  of the epitaxial layer  122 . The isolation regions  132  may correspond to the non-conductive lanes described above. The isolation regions  132  may electrically isolate portions of the active region of the epitaxial layer  122  from one another. These isolated portions may define pixels  134 . The pixels  134  may be similar to the pixels  111  described above. The pixels  134  may have a width of approximately 25 μm to approximately 300 μm 
     The dopant atoms may be atoms or molecules that provide electrical isolation between portions of the active region  127 . For example, the dopant atoms may be protons such as, for example hydrogen, argon, and/or helium. The isolation regions  132  may have a uniform or non-uniform distribution of the dopant atoms. The isolation regions  132  may have a depth Y 132  from the upper surface  130 . The depth Y 132  may extend through the epitaxial layer  122  to at least a distance that extends through the active region  127 . In an embodiment, the depth Y 132  may be approximately 0.5 μm to several microns. The isolation regions  132  may have a width of approximately 1 μm to approximately 100 μm. 
     The dopant atoms may be implanted in a direction that is normal to the upper surface  130  of the epitaxial layer  122 . While the implant angle (i.e., the angle between the impinging dopant atoms and the surface normal to the upper surface  130 ), may be nominally zero, non-substantial deviations from normal incidence may be used for the dopant atom implantation step to minimize any adverse effect of channeling of ions. 
     The dopant atoms may be implanted using a single ion implantation step employing a target ion implantation energy and a target dose, or may be implanted using multiple ion implantation steps each having different target ion implantation energy and a target dose. If multiple ion implantation steps having different ion energies are employed, the dopant profile after the multiple ion implantation steps may be the superposition of all individual ion implantation steps. The target ion implantation energy may range from 20 keV to 1 MeV, although lesser and greater target ion implantation energies may be employed. 
       FIG. 1J  shows another example of the isolation regions  132 . In this example, the isolation regions  132  may have one or more underlap regions  136  extending laterally in the epitaxial layer  122  below the reflective layer  124 . The underlap portions  136  may be a result of the ion implantation process and may include the dopant atoms implanted during the ion implantation process. The dopant atoms may diffuse laterally in the epitaxial layer  122  such that they have a width X 136  approximately 0.1 μm to approximately 0.5 μm. It should be noted that the underlap portions  136  may be present in any of the embodiments described herein. 
       FIG. 1K  shows another example of the isolation regions  132 . In this example, the isolation regions  132  may have a width that is less than the width of the trench  128 . This may be a result of the ion implantation process. It should be noted that isolation regions  132  having a smaller width than the trench  128  may be present in any of the embodiments described herein. 
     Referring now to  FIG. 1L , a cross section view illustrating removing the resist layer  126  is shown. The resist layer  126  may be removed selective to the reflective layer  124  and the isolation regions  132 . The resist layer  126  may be removed using a conventional process, such as stripping or a wet etch. The removal of the resist layer  126  may expose the reflective layer  124 . 
     Referring now to  FIG. 1M , a cross section view illustrating forming a p-type contact layer  138  on the reflective layer  124  is shown. The p-type contact layer  138  may be formed using a conventional deposition technique, such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. In an example, the p-type contact layer  138  may be blanket deposited over the reflective layer  124  and the isolation regions  132  and then patterned and etched to expose the upper surface  130 . The p-type contact layer  138  may compose one or more layers of a conductive metal or metal alloy, such as, gold, silver, copper. 
     Referring now to  FIG. 1N , a cross section view illustrating removing the sapphire substrate  120  is shown. The sapphire substrate  120  may be removed by a conventional process such as grinding, chemical mechanical polishing (CMP), or laser lift-off. The removal of the sapphire substrate  120  may expose a bottom surface  1002  of the epitaxial layer  122 . In an example, the bottom surface  1002  may be roughened after it is exposed. 
     It should be noted that the isolation regions  132  may be formed using a conventional patterning and etching process in which a portion of the epitaxial layer  122  exposed by the trench  128  may be removed to form an opening. The opening may be filled with a dielectric material such as an oxide or a nitride using a conventional deposition process. Isolation regions  132  composed of dielectric material may be present in any of the embodiments described herein. 
     Referring now to  FIG. 10 , a cross section view illustrating forming a common n-contact layer  140  on the bottom surface  1002  of the epitaxial layer  122  is shown. The common n-contact layer  140  may compose a blanket transparent conductor. In an example, the common n-type contact layer  140  may compose a transparent conductive oxide (TCO), such as indium tin oxide (ITO). The common n-type contact layer  140  may be formed using a conventional deposition technique, such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. Because the sapphire substrate  120  is removed, a wavelength converting layer  142  may be mounted directly on the common n-type contact layer  140  directly below the pixels  134 . 
     The wavelength converting layer  142  may compose elemental phosphor or compounds thereof. The wavelength converting layer  142  may be formed using a conventional deposition technique, 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 like processes. 
     The wavelength converting layer  142  may contain one or more phosphors. Phosphors are luminescent materials that may absorb an excitation energy (usually radiation energy), and then emit the absorbed energy as radiation of a different energy than the initial excitation energy. The phosphors may have quantum efficiencies near  100 %, meaning nearly all photons provided as excitation energy may be reemitted by the phosphors. The phosphors may also be highly absorbent. Because the light emitting active region may emit light directly into the highly efficient, highly absorbent wavelength converting layer  142 , the phosphors may efficiently extract light from the device. The phosphors used in the wavelength converting layer  142  may include, but are not limited to any conventional green, yellow, and red emitting phosphors. 
     The wavelength converting layer  142  may be formed by depositing grains of phosphor on the common n-contact layer  140 . The phosphor grains may be in direct contact with the common n-contact layer  140 , such that light emitted from an active region may be directly coupled to the phosphor grains. Although not shown in  FIG. 1V , an optical coupling medium may be provided to hold the phosphor grains in place. The optical coupling medium may be selected to have a refractive index that is as close as possible without significantly exceeding the index of refraction of the epitaxial layer  146 . For most efficient operation, no lossy media may be included between the epitaxial layer  146 , the phosphor grains of the wavelength converting layer  142 , and the optical coupling medium. 
     The phosphor grains may have a grain size between 0.1 μm and 20 μm. The phosphor grains may be applied by, for example, electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques to form the wavelength converting layer  142 . In techniques such as spin coating or spray coating, the phosphor may be disposed in a slurry with an organic binder, which may then evaporated after deposit of the slurry by, for example, heating. Optionally, the optical coupling medium may then be applied. Phosphor particles may be nanoparticles themselves (i.e., particles ranging from 100 nm to 1000 nm in size). Spherical phosphor particles, typically produced by spray pyrolysis methods or other methods can be applied, yielding a layer with a high package density which provides advantageous scattering properties. Also, phosphors particles may be coated, for example with a material with a band gap larger than the light emitted by the phosphor, such as SiO 2 , Al 2 O 3 , MePO 4  or -polyphosphate, or other suitable metal oxides. 
     The wavelength converting layer  142  may be a ceramic phosphor, rather than a phosphor powder. A ceramic phosphor may be formed by heating a powder phosphor at high pressure until the surface of the phosphor particles begin to soften and melt. The partially-melted particles may stick together to form a rigid agglomerate of particles. Uniaxial or isostatic pressing steps and vacuum sintering of the preformed “green body” may be necessary to form a polycrystalline ceramic layer. The translucency of the ceramic phosphor (i.e., the amount of scattering it produces) may be controlled from high opacity to high transparency by adjusting the heating or pressing conditions, the fabrication method, the phosphor particle precursor used, and the suitable crystal lattice of the phosphor material. Besides phosphor, other ceramic forming materials such as alumina may be included, for example to facilitate formation of the ceramic or to adjust the refractive index of the ceramic. 
     The wavelength converting layer  142  may compose a mixture of silicone and phosphor particles. In this example, the wavelength converting layer  142  may be diced from plates and placed on a lower surface of the common n-contact layer  140 . 
     An alternative process of forming the pixels  111  is described in detail below. In an example, a laterally extending sapphire substrate may be partially or completely removed to reduce adverse effects to pixel optical isolation due to light waveguide properties of the continuous sapphire substrate. Walls attached to the epitaxial layer  146  may retain and define a well for phosphor power deposition. The walls may be additively formed (e.g., by plating metal), subtractively formed (e.g., by etching the sapphire substrate), or may be formed by a combination of the processes. 
     Referring now to  FIG. 1P , a cross section view of a reflective layer  148  formed on an epitaxial layer  146  is shown. The epitaxial layer  146  may be formed on a sapphire substrate  144 . The sapphire substrate  144  may be similar to the sapphire substrate  120  described above and may be formed using similar methods as those described above. The epitaxial layer  146  may be similar to the epitaxial layer  122  described above and may be formed using similar methods as those described above. 
     Referring now to  FIG. 1Q , a cross section view illustrating removing portions of the reflective layer  148  and the epitaxial layer  146  is shown. The portions of the reflective layer  148  and the epitaxial layer  146  may be removed using a conventional etching process, such as, for example, wet etching, plasma etching, and RIE. The etching process may form one or more pixels  157  similar to the pixels  134  described above. The reflective layer  148  may be etched such that portions  150  adjacent to the etched portions of the epitaxial layer have one or more angled sidewalls. 
     Referring now to  FIG. 1R , a cross section view of forming a dielectric layer  152  and an n-type contact  154  is shown. The dielectric layer  152  may compose electrically insulating material, such as, for example an oxide or a nitride. The dielectric layer  152  may be formed on the epitaxial layer  146  using a conventional conformal deposition process. Portions of the dielectric layer  152  may be removed using a conventional patterning and etching process to expose portions of the epitaxial layer  146 . The n-type contact  154  may compose a blanket transparent conductor. In an example, the n-type contact layer  154  may compose a TCO, such as indium tin oxide ITO. The n-type contact layer  154  may be formed using a conventional deposition technique, such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. The n-type contact layer  154  may be formed using a conformal deposition process. The n-type contact layer  154  may be in contact with the epitaxial layer  146  in areas exposed by openings in the dielectric layer  152 . 
     Referring now to  FIG. 1S , a cross section view of a LED array  1200  is shown. It should be noted that the LED array  1200  may take any configuration and still be consistent with the embodiments described herein. In an example, the LED array  1200  may be a conventional LED array formed on the sapphire substrate  144  using conventional techniques. In another example, the LED array  1200  may be formed using the techniques described above. 
     A portion of the n-type contact layer  154  and a portion of the dielectric layer  152  may be removed to expose an upper surface of a pixel  157 . A p-type contact  156  may be formed on the exposed surface of the pixel  157 . The p-type contact  156  may be formed using a conventional deposition technique, such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. The p-type contact  156  may compose one or more layers of a conductive metal or metal alloy, such as, gold, silver, copper. 
     Referring now to  FIGS. 13-15 , cross section views illustrating a method of forming a well for phosphor deposition are shown.  FIG. 1T  illustrates removing the sapphire substrate  144  from the epitaxial layer  146 . The sapphire substrate  144  may be completely removed from the epitaxial layer  146 , exposing a lower surface  158  of the epitaxial layer  146 . The sapphire substrate  144  may be removed by a conventional process such as grinding, chemical mechanical polishing (CMP), or laser lift-off. 
       FIG. 1U  illustrates forming walls  160  on the lower surface  158  of the epitaxial layer  146 . The walls  160  may compose any type of material that can be deposited on the lower surface and provide a desired degree of physical and optical isolation between one or more wavelength converting layers. For example, the walls may compose a dielectric material, a metal, a semiconductor material, or combinations thereof. The walls  160  may be formed using a conventional deposition technique, such as, for example, CVD, PECVD, MOCVD, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes. In an example, the walls  160  may be formed by depositing a blanket layer on the lower surface  158 . The blanket layer may be patterned and etched to form the walls  160 . In another example, a resist layer (not shown) may be formed on the lower surface  158 . The resist layer may be patterned and etched to form openings. The walls  160  may be formed by depositing the desired materials within the openings and subsequently removing the excess material and resist layer. In another example, the walls  160  may be formed using selective plating. The walls  160  may be located on the lower surface  158  such that they are directly below areas separating the pixels  157 . The walls  160  may define wells  162  below the pixels  157 . 
       FIG. 1V  illustrates forming a wavelength converting layer  164  within the wells  162 . The wavelength converting layer  164  may compose elemental phosphor or compounds thereof. The wavelength converting layer  164  may be formed using a conventional deposition technique, 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 like processes. 
     The wavelength converting layer  164  may contain one or more phosphors. Phosphors are luminescent materials that may absorb an excitation energy (usually radiation energy), and then emit the absorbed energy as radiation of a different energy than the initial excitation energy. The phosphors may have quantum efficiencies near  100 %, meaning nearly all photons provided as excitation energy may be reemitted by the phosphors. The phosphors may also be highly absorbent. Because the light emitting active region may emit light directly into the highly efficient, highly absorbent wavelength converting layer  164 , the phosphors may efficiently extract light from the device. The phosphors used in the wavelength converting layer  164  may include, but are not limited to any conventional green, yellow, and red emitting phosphors. 
     The wavelength converting layer  164  may be formed by depositing grains of phosphor on the lower surface  158 . The phosphor grains may be in direct contact with the epitaxial layer  146 , such that light emitted from an active region may be directly coupled to the phosphor grains. Although not shown in  FIG. 1V , an optical coupling medium may be provided to hold the phosphor grains in place. The optical coupling medium may be selected to have a refractive index that is as close as possible without significantly exceeding the index of refraction of the epitaxial layer  146 . For most efficient operation, no lossy media may be included between the epitaxial layer  146 , the phosphor grains of the wavelength converting layer  164 , and the optical coupling medium. 
     The phosphor grains may have a grain size between 0.1 μm and 20 μm. The phosphor grains may be applied by, for example, electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques to form the wavelength converting layer  164 . In techniques such as spin coating or spray coating, the phosphor may be disposed in a slurry with an organic binder, which may then evaporated after deposit of the slurry by, for example, heating. Optionally, the optical coupling medium may then be applied. Phosphor particles may be nanoparticles themselves (i.e., particles ranging from 100 nm to 1000 nm in size). Spherical phosphor particles, typically produced by spray pyrolysis methods or other methods can be applied, yielding a layer with a high package density which provides advantageous scattering properties. Also, phosphors particles may be coated, for example with a material with a band gap larger than the light emitted by the phosphor, such as SiO 2 , Al 2 O 3 , MePO 4  or -polyphosphate, or other suitable metal oxides. 
     The wavelength converting layer  164  may be a ceramic phosphor, rather than a phosphor powder. A ceramic phosphor may be formed by heating a powder phosphor at high pressure until the surface of the phosphor particles begin to soften and melt. The partially-melted particles may stick together to form a rigid agglomerate of particles. Uniaxial or isostatic pressing steps and vacuum sintering of the preformed “green body” may be necessary to form a polycrystalline ceramic layer. The translucency of the ceramic phosphor (i.e., the amount of scattering it produces) may be controlled from high opacity to high transparency by adjusting the heating or pressing conditions, the fabrication method, the phosphor particle precursor used, and the suitable crystal lattice of the phosphor material. Besides phosphor, other ceramic forming materials such as alumina may be included, for example to facilitate formation of the ceramic or to adjust the refractive index of the ceramic. 
     The wavelength converting layer  164  may compose a mixture of silicone and phosphor particles. In this example, the wavelength converting layer  164  may be diced from plates and placed on the lower surface  158  of the epitaxial layer  146 . 
     Referring now to  FIGS. 16-17 , cross section views illustrating another method of forming a well for phosphor deposition are shown.  FIG. 1W  illustrates removing portions of the sapphire substrate  144  from the epitaxial layer  146 . The portions of the sapphire substrate  144  may be removed from the epitaxial layer  146 , exposing the lower surface  158  of the epitaxial layer  146 . The sapphire substrate  144  may be removed by a conventional etching process. The remaining portions of the sapphire substrate  144  may form walls  166  located on the lower surface  158  such that they are directly below areas separating the pixels  157 . The walls  166  may define wells  168  below the pixels  157 . 
       FIG. 1X  illustrates forming a wavelength converting layer  170  within the wells  168 . The wavelength converting layer  170  may compose elemental phosphor or compounds thereof. The wavelength converting layer  164  may be formed using a conventional deposition technique, 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 like processes. 
     The wavelength converting layer  170  may contain one or more phosphors. Phosphors are luminescent materials that may absorb an excitation energy (usually radiation energy), and then emit the absorbed energy as radiation of a different energy than the initial excitation energy. The phosphors may have quantum efficiencies near 100%, meaning nearly all photons provided as excitation energy may be reemitted by the phosphors. The phosphors may also be highly absorbent. Because the light emitting active region may emit light directly into the highly efficient, highly absorbent wavelength converting layer  170 , the phosphors may efficiently extract light from the device. The phosphors used in the wavelength converting layer  170  may include, but are not limited to any conventional green, yellow, and red emitting phosphors. 
     The wavelength converting layer  170  may be formed by depositing grains of phosphor on the lower surface  158 . The phosphor grains may be in direct contact with the epitaxial layer  146 , such that light emitted from an active region may be directly coupled to the phosphor grains. Although not shown in  FIG. 1X , an optical coupling medium may be provided to hold the phosphor grains in place. The optical coupling medium may be selected to have a refractive index that is as close as possible without significantly exceeding the index of refraction of the epitaxial layer  146 . For most efficient operation, no lossy media may be included between the epitaxial layer  146 , the phosphor grains of the wavelength converting layer  170 , and the optical coupling medium. 
     The phosphor grains may have a grain size between 0.1 μm and 20 μm. The phosphor grains may be applied by, for example, electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques to form the wavelength converting layer  170 . In techniques such as spin coating or spray coating, the phosphor may be disposed in a slurry with an organic binder, which may then evaporated after deposit of the slurry by, for example, heating. Optionally, the optical coupling medium may then be applied. Phosphor particles may be nanoparticles themselves (i.e., particles ranging from 100 nm to 1000 nm in size). Spherical phosphor particles, typically produced by spray pyrolysis methods or other methods can be applied, yielding a layer with a high package density which provides advantageous scattering properties. Also, phosphors particles may be coated, for example with a material with a band gap larger than the light emitted by the phosphor, such as SiO 2 , Al 2 O 3 , MePO 4  or -polyphosphate, or other suitable metal oxides. 
     The wavelength converting layer  170  may be a ceramic phosphor, rather than a phosphor powder. A ceramic phosphor may be formed by heating a powder phosphor at high pressure until the surface of the phosphor particles begin to soften and melt. The partially-melted particles may stick together to form a rigid agglomerate of particles. Uniaxial or isostatic pressing steps and vacuum sintering of the preformed “green body” may be necessary to form a polycrystalline ceramic layer. The translucency of the ceramic phosphor (i.e., the amount of scattering it produces) may be controlled from high opacity to high transparency by adjusting the heating or pressing conditions, the fabrication method, the phosphor particle precursor used, and the suitable crystal lattice of the phosphor material. Besides phosphor, other ceramic forming materials such as alumina may be included, for example to facilitate formation of the ceramic or to adjust the refractive index of the ceramic. 
     The wavelength converting layer  170  may compose a mixture of silicone and phosphor particles. In this example, the wavelength converting layer  170  may be diced from plates and placed on the lower surface  158  of the epitaxial layer  146 . 
     Referring now to  FIGS. 18-20 , cross section views illustrating another method of forming a well for phosphor deposition are shown.  FIG. 1Y  illustrates a cross section view of a LED array  1800  formed on a sapphire substrate  172 . It should be noted that the LED array  1800  may take any configuration and still be consistent with the embodiments described herein. In an example, the LED array  1800  may be a conventional LED array formed on the sapphire substrate  158  using conventional techniques. In another example, the LED array  1800  may be formed using the techniques described above. 
     The LED array  1800  may include an epitaxial layer  174  formed on the sapphire substrate  172 . The sapphire substrate  172  may compose a crystalline material, such as aluminum oxide, and may be a commercial sapphire wafer. The sapphire substrate  172  may be etched, pattern, or grooved, such that the sapphire substrate  172  has recesses  176 . The recesses  176  may be formed using conventional patterning and etching techniques. 
     The epitaxial layer  174  may compose any Group III-V semiconductors, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. In an example, the epitaxial layer  174  may compose GaN. The epitaxial layer  174  may be formed using conventional deposition techniques, such as MOCVD, MBE, or other epitaxial techniques. In an epitaxial deposition process, chemical reactants provided by one or more source gases are controlled and the system parameters are set so that depositing atoms arrive at a deposition surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms of the deposition surface. Accordingly, the epitaxial layer  174  may be grown on the sapphire substrate  172  using conventional epitaxial techniques. The epitaxial layer  174  may extend into the recesses  176  formed in the sapphire substrate. 
     The LED array  1800  may also include the reflective layer  148 , the dielectric layer  152 , the n-type contact  154 , and the p-type contact  156 . The portions  150  of the reflective layer  148  may be etched such that they have one or more angled sidewalls. The LED array  1800  may have defined pixels  157  similar to those described above. As described above, the LED array  1800  may take any configuration known in the art. 
       FIG. 1Z  illustrates removing the sapphire substrate  172 . The sapphire substrate  172  may be removed from the epitaxial layer  174 , exposing a lower surface  178  of the epitaxial layer  174 . The sapphire substrate  172  may be removed by a conventional etching process. The portions of the epitaxial layer  174  grown in the recesses  182  may form walls  180 . The walls  180  may be directly below areas separating the pixels  157 . The walls  180  may define wells  182  below the pixels  157 . 
       FIG. 1AA  illustrates forming a wavelength converting layer  184  within the wells  182 . The wavelength converting layer  184  may compose elemental phosphor or compounds thereof. The wavelength converting layer  184  may be formed using a conventional deposition technique, 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 like processes. 
     The wavelength converting layer  184  may contain one or more phosphors. Phosphors are luminescent materials that may absorb an excitation energy (usually radiation energy), and then emit the absorbed energy as radiation of a different energy than the initial excitation energy. The phosphors may have quantum efficiencies near  100 %, meaning nearly all photons provided as excitation energy may be reemitted by the phosphors. The phosphors may also be highly absorbent. Because the light emitting active region may emit light directly into the highly efficient, highly absorbent wavelength converting layer  184 , the phosphors may efficiently extract light from the device. The phosphors used in the wavelength converting layer  184  may include, but are not limited to any conventional green, yellow, and red emitting phosphors. 
     The wavelength converting layer  184  may be formed by depositing grains of phosphor on the lower surface  158 . The phosphor grains may be in direct contact with the epitaxial layer  174 , such that light emitted from an active region may be directly coupled to the phosphor grains. Although not shown in  FIG. 1AA , an optical coupling medium may be provided to hold the phosphor grains in place. The optical coupling medium may be selected to have a refractive index that is as close as possible without significantly exceeding the index of refraction of the epitaxial layer  174 . For most efficient operation, no lossy media may be included between the epitaxial layer  174 , the phosphor grains of the wavelength converting layer  184 , and the optical coupling medium. 
     The phosphor grains may have a grain size between 0.1 μm and 20 μm. The phosphor grains may be applied by, for example, electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques to form the wavelength converting layer  184 . In techniques such as spin coating or spray coating, the phosphor may be disposed in a slurry with an organic binder, which may then evaporated after deposit of the slurry by, for example, heating. Optionally, the optical coupling medium may then be applied. Phosphor particles may be nanoparticles themselves (i.e., particles ranging from 100 nm to 1000 nm in size). Spherical phosphor particles, typically produced by spray pyrolysis methods or other methods can be applied, yielding a layer with a high package density which provides advantageous scattering properties. Also, phosphors particles may be coated, for example with a material with a band gap larger than the light emitted by the phosphor, such as SiO 2 , Al 2 O 3 , MePO 4  or -polyphosphate, or other suitable metal oxides. 
     The wavelength converting layer  184  may be a ceramic phosphor, rather than a phosphor powder. A ceramic phosphor may be formed by heating a powder phosphor at high pressure until the surface of the phosphor particles begin to soften and melt. The partially-melted particles may stick together to form a rigid agglomerate of particles. Uniaxial or isostatic pressing steps and vacuum sintering of the preformed “green body” may be necessary to form a polycrystalline ceramic layer. The translucency of the ceramic phosphor (i.e., the amount of scattering it produces) may be controlled from high opacity to high transparency by adjusting the heating or pressing conditions, the fabrication method, the phosphor particle precursor used, and the suitable crystal lattice of the phosphor material. Besides phosphor, other ceramic forming materials such as alumina may be included, for example to facilitate formation of the ceramic or to adjust the refractive index of the ceramic. 
     The wavelength converting layer  184  may compose a mixture of silicone and phosphor particles. In this example, the wavelength converting layer  184  may be diced from plates and placed on the lower surface  158  of the epitaxial layer  174 . 
     Referring now to  FIGS. 1AB-1AD , cross section views illustrating another method of forming a well for phosphor deposition are shown.  FIG. 1AB  illustrates a cross section view of a LED array  2100  formed on a sapphire substrate  186 . It should be noted that the LED array  2100  may take any configuration and still be consistent with the embodiments described herein. In an example, the LED array  2100  may be a conventional LED array formed on the sapphire substrate  186  using conventional techniques. In another example, the LED array  2100  may be formed using the techniques described above. 
     The LED array  2100  may include an epitaxial layer  188  formed on the sapphire substrate  186 . The sapphire substrate  186  may compose a crystalline material, such as aluminum oxide, and may be a commercial sapphire wafer. The sapphire substrate  186  and the epitaxial layer  188  may be etched to form a trench that is subsequently filled with the material used to form the n-type contact  154 . The sapphire substrate  186  and the epitaxial layer  188  may be etched using conventional patterning and etching techniques. The n-type contact  154  may extend through at least a portion of the sapphire substrate  186 . 
     The epitaxial layer  188  may compose any Group III-V semiconductors, including binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. In an example, the epitaxial layer  188  may compose GaN. The epitaxial layer  188  may be formed using conventional deposition techniques, such as MOCVD, MBE, or other epitaxial techniques. In an epitaxial deposition process, chemical reactants provided by one or more source gases are controlled and the system parameters are set so that depositing atoms arrive at a deposition surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms of the deposition surface. Accordingly, the epitaxial layer  188  may be grown on the sapphire substrate  172  using conventional epitaxial techniques. 
     The LED array  2100  may also include the reflective layer  148 , the dielectric layer  152 , the n-type contact  154 , and the p-type contact  156 . The portions  150  of the reflective layer  148  may be etched such that they have one or more angled sidewalls. The LED array  1800  may have defined pixels  157  similar to those described above. As described above, the LED array  1800  may take any configuration known in the art. 
       FIG. 1AC  illustrates removing the sapphire substrate  186 . The sapphire substrate  186  may be removed from the epitaxial layer  188 , exposing a lower surface  190  of the epitaxial layer  188  and the n-type contacts  154 . The sapphire substrate  186  may be removed by a conventional etching process. The n-type contacts  154  may form walls  192 . The walls  192  may be directly below areas separating the pixels  157 . The walls  192  may define wells  194  below the pixels  157 . 
       FIG. 1AD  illustrates forming a wavelength converting layer  196  within the wells  194 . The wavelength converting layer  196  may compose elemental phosphor or compounds thereof. The wavelength converting layer  196  may be formed using a conventional deposition technique, 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 like processes. 
     The wavelength converting layer  196  may contain one or more phosphors. Phosphors are luminescent materials that may absorb an excitation energy (usually radiation energy), and then emit the absorbed energy as radiation of a different energy than the initial excitation energy. The phosphors may have quantum efficiencies near 100%, meaning nearly all photons provided as excitation energy may be reemitted by the phosphors. The phosphors may also be highly absorbent. Because the light emitting active region may emit light directly into the highly efficient, highly absorbent wavelength converting layer  196 , the phosphors may efficiently extract light from the device. The phosphors used in the wavelength converting layer  196  may include, but are not limited to any conventional green, yellow, and red emitting phosphors. 
     The wavelength converting layer  196  may be formed by depositing grains of phosphor on the lower surface  190 . The phosphor grains may be in direct contact with the epitaxial layer  188 , such that light emitted from an active region may be directly coupled to the phosphor grains. Although not shown in  FIG. 1AD , an optical coupling medium may be provided to hold the phosphor grains in place. The optical coupling medium may be selected to have a refractive index that is as close as possible without significantly exceeding the index of refraction of the epitaxial layer  188 . For most efficient operation, no lossy media may be included between the epitaxial layer  188 , the phosphor grains of the wavelength converting layer  196 , and the optical coupling medium. 
     The phosphor grains may have a grain size between 0.1 μm and 20 μm. The phosphor grains may be applied by, for example, electrophoretic deposition, spin coating, spray coating, screen printing, or other printing techniques to form the wavelength converting layer  196 . In techniques such as spin coating or spray coating, the phosphor may be disposed in a slurry with an organic binder, which may then evaporated after deposit of the slurry by, for example, heating. Optionally, the optical coupling medium may then be applied. Phosphor particles may be nanoparticles themselves (i.e., particles ranging from 100 nm to 1000 nm in size). Spherical phosphor particles, typically produced by spray pyrolysis methods or other methods can be applied, yielding a layer with a high package density which provides advantageous scattering properties. Also, phosphors particles may be coated, for example with a material with a band gap larger than the light emitted by the phosphor, such as SiO 2 , Al 2 O 3 , MePO 4  or -polyphosphate, or other suitable metal oxides. 
     The wavelength converting layer  196  may be a ceramic phosphor, rather than a phosphor powder. A ceramic phosphor may be formed by heating a powder phosphor at high pressure until the surface of the phosphor particles begin to soften and melt. The partially-melted particles may stick together to form a rigid agglomerate of particles. Uniaxial or isostatic pressing steps and vacuum sintering of the preformed “green body” may be necessary to form a polycrystalline ceramic layer. The translucency of the ceramic phosphor (i.e., the amount of scattering it produces) may be controlled from high opacity to high transparency by adjusting the heating or pressing conditions, the fabrication method, the phosphor particle precursor used, and the suitable crystal lattice of the phosphor material. Besides phosphor, other ceramic forming materials such as alumina may be included, for example to facilitate formation of the ceramic or to adjust the refractive index of the ceramic. 
     The wavelength converting layer  196  may compose a mixture of silicone and phosphor particles. In this example, the wavelength converting layer  196  may be diced from plates and placed on the lower surface  158  of the epitaxial layer  188 . 
     Referring now to  FIG. 1AE , a flowchart illustrating a method of forming a device is shown. In step  131 , a trench may be formed in a trench in a p-type contact layer and a reflective layer to expose an epitaxial layer. In step  133 , an isolation region may be formed in in the epitaxial layer exposed by the trench using ion implantation. The isolation region may separate a first pixel and a second pixel and may have a width that is at least a width of the trench. In step  135 , a common n-type contact layer may be formed on the epitaxial layer. The common n-type contact layer may be distal to the reflective layer. In an optional step  137 , a wavelength converting region may be formed on the common n-type contact layer. 
     It should be noted that the term “distal” as used herein may be used as a directional term to mean a spatially opposites sides of an element, device, layer, or other structure. A first element and a second element that are on distal sides of a third element may be separated from one another by at least a portion of the third element. For example, an upper surface of a layer may be distal to a lower surface of the layer. 
       FIG. 2A  is a top view of an electronics board with an LED array  410  attached to a substrate at the LED device attach region  318  in one embodiment. The electronics board together with the LED array  410  represents an LED system  400 A. Additionally, the power module  312  receives a voltage input at Vin  497  and control signals from the connectivity and control module  316  over traces  418 B, and provides drive signals to the LED array  410  over traces  418 A. The LED array  410  is turned on and off via the drive signals from the power module  312 . In the embodiment shown in  FIG. 2A , the connectivity and control module  316  receives sensor signals from the sensor module  314  over trace  4180 . 
       FIG. 2B  illustrates one embodiment of a two channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board  499 . As shown in  FIG. 2B , an LED lighting system  400 B includes a first surface  445 A having inputs to receive dimmer signals and AC power signals and an AC/DC converter circuit  412  mounted on it. The LED system  400 B includes a second surface  445 B with the dimmer interface circuit  415 , DC-DC converter circuits  440 A and  440 B, a connectivity and control module  416  (a wireless module in this example) having a microcontroller  472 , and an LED array  410  mounted on it. The LED array  410  is driven by two independent channels  411 A and  411 B. In alternative embodiments, a single channel may be used to provide the drive signals to an LED array, or any number of multiple channels may be used to provide the drive signals to an LED array. 
     The LED array  410  may include two groups of LED devices. In an example embodiment, the LED devices of group A are electrically coupled to a first channel  411 A and the LED devices of group B are electrically coupled to a second channel  411 B. Each of the two DC-DC converters  440 A and  440 B may provide a respective drive current via single channels  411 A and  411 B, respectively, for driving a respective group of LEDs A and B in the LED array  410 . The LEDs in one of the groups of LEDs may be configured to emit light having a different color point than the LEDs in the second group of LEDs. Control of the composite color point of light emitted by the LED array  410  may be tuned within a range by controlling the current and/or duty cycle applied by the individual DC/DC converter circuits  440 A and  440 B via a single channel  411 A and  411 B, respectively. Although the embodiment shown in  FIG. 2B  does not include a sensor module (as described in  FIG. 2A ), an alternative embodiment may include a sensor module. 
     The illustrated LED lighting system  400 B is an integrated system in which the LED array  410  and the circuitry for operating the LED array  410  are provided on a single electronics board. Connections between modules on the same surface of the circuit board  499  may be electrically coupled for exchanging, for example, voltages, currents, and control signals between modules, by surface or sub-surface interconnections, such as traces  431 ,  432 ,  433 ,  434  and  435  or metallizations (not shown). Connections between modules on opposite surfaces of the circuit board  499  may be electrically coupled by through board interconnections, such as vias and metallizations (not shown). 
     According to embodiments, LED systems may be provided where an LED array is on a separate electronics board from the driver and control circuitry. According to other embodiments, a LED system may have the LED array together with some of the electronics on an electronics board separate from the driver circuit. For example, an LED system may include a power conversion module and an LED module located on a separate electronics board than the LED arrays. 
     According to embodiments, an LED system may include a multi-channel LED driver circuit. For example, an LED module may include embedded LED calibration and setting data and, for example, three groups of LEDs. One of ordinary skill in the art will recognize that any number of groups of LEDs may be used consistent with one or more applications. Individual LEDs within each group may be arranged in series or in parallel and the light having different color points may be provided. For example, warm white light may be provided by a first group of LEDs, a cool white light may be provided by a second group of LEDs, and a neutral white light may be provided by a third group. 
       FIG. 2C  shows an example vehicle headlamp system  300  including a vehicle power  302  including a data bus  304 . A sensor module  307  may be connected to the data bus  304  to provide data related to environment conditions (e.g. ambient light conditions, temperature, time, rain, fog, etc), vehicle condition (parked, in-motion, speed, direction), presence/position of other vehicles, pedestrians, objects, or the like. The sensor module  307  may be similar to or the same as the sensor module  314  of  FIG. 2A . AC/DC Converter  305  may be connected to the vehicle power  302 . 
     The AC/DC converter  312  of  FIG. 2C  may be the same as or similar to the AC/DC converter  412  of  FIG. 2B  and may receive AC power from the vehicle power  302 . It may convert the AC power to DC power as described in  FIG. 2B  for AC-DC converter  412 . The vehicle head lamp system  300  may include an active head lamp  330  which receives one or more inputs provided by or based on the AC/DC converter  305 , connectivity and control module  306 , and/or sensor module  307 . As an example, the sensor module  307  may detect the presence of a pedestrian such that the pedestrian is not well lit, which may reduce the likelihood that a driver sees the pedestrian. Based on such sensor input, the connectivity and control module  306  may output data to the active head lamp  330  using power provided from the AC/DC converter  305  such that the output data activates a subset of LEDs in an LED array contained within active head lamp  330 . The subset of LEDs in the LED array, when activated, may emit light in the direction where the sensor module  307  sensed the presence of the pedestrian. These subset of LEDs may be deactivated or their light beam direction may otherwise be modified after the sensor module  207  provides updated data confirming that the pedestrian is no longer in a path of the vehicle that includes vehicle head lamp system. 
       FIG. 3  shows an example system  550  which includes an application platform  560 , LED systems  552  and  556 , and optics  554  and  558 . The LED System  552  produces light beams  561  shown between arrows  561   a  and  561   b . The LED System  556  may produce light beams  562  between arrows  562   a  and  562   b . In the embodiment shown in  FIG. 3 , the light emitted from LED System  552  passes through secondary optics  554 , and the light emitted from the LED System  556  passes through secondary optics  554 . In alternative embodiments, the light beams  561  and  562  do not pass through any secondary optics. The secondary optics may be or may include one or more light guides. The one or more light guides may be edge lit or may have an interior opening that defines an interior edge of the light guide. LED systems  552  and/or  556  may be inserted in the interior openings of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or exterior edge (edge lit light guide) of the one or more light guides. LEDs in LED systems  552  and/or  556  may be arranged around the circumference of a base that is part of the light guide. According to an implementation, the base may be thermally conductive. According to an implementation, the base may be coupled to a heat-dissipating element that is disposed over the light guide. The heat-dissipating element may be arranged to receive heat generated by the LEDs via the thermally conductive base and dissipate the received heat. The one or more light guides may allow light emitted by LED systems  552  and  556  to be shaped in a desired manner such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, an angular distribution, or the like. 
     In example embodiments, the system  550  may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor light such as street lighting, an automobile, a medical device, AR/VR devices, and robotic devices. The LED System  400 A shown in  FIG. 2A  and vehicle head lamp system  300  shown in  FIG. 2C  illustrate LED systems  552  and  556  in example embodiments. 
     The application platform  560  may provide power to the LED systems  552  and/or  556  via a power bus via line  565  or other applicable input, as discussed herein. Further, application platform  560  may provide input signals via line  565  for the operation of the LED system  552  and LED system  556 , which input may be based on a user input/preference, a sensed reading, a pre-programmed or autonomously determined output, or the like. One or more sensors may be internal or external to the housing of the application platform  560 . Alternatively or in addition, as shown in the LED system  400  of  FIG. 2A , each LED System  552  and  556  may include its own sensor module, connectivity and control module, power module, and/or LED devices. 
     In embodiments, application platform  560  sensors and/or LED system  552  and/or  556  sensors may collect data such as 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 a combination thereof. The data may be related a physical item or entity such as an object, an individual, a vehicle, etc. For example, sensing equipment may collect object proximity data for an ADAS/AV based application, which may prioritize the detection and subsequent action based on the detection of a physical item or entity. The data may be collected based on emitting an optical signal by, for example, LED system  552  and/or  556 , such as an IR signal and collecting data based on the emitted optical signal. The data may be collected by a different component than the component that emits the optical signal for the data collection. Continuing the example, sensing equipment may be located on an automobile and may emit a beam using a vertical-cavity surface-emitting laser (VCSEL). The one or more sensors may sense a response to the emitted beam or any other applicable input. 
     In example embodiment, application platform  560  may represent an automobile and LED system  552  and LED system  556  may represent automobile headlights. In various embodiments, the system  550  may represent an automobile with steerable light beams where LEDs may be selectively activated to provide steerable light. For example, an array of LEDs may be used to define or project a shape or pattern or illuminate only selected sections of a roadway. In an example embodiment, Infrared cameras or detector pixels within LED systems  552  and/or  556  may be sensors (e.g., similar to sensors module  314  of  FIG. 2A and 307  of  FIG. 2C ) that identify portions of a scene (roadway, pedestrian crossing, etc.) that require illumination. 
     Having described the embodiments in detail, those skilled in the art will appreciate that, given the present description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.