Inorganic light conversion module

Abstract

A method of preparing an inorganic bonding layer comprises: conducting electrophoresis to deposit particles of an inorganic material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; fixing the particles of the inorganic material with a binder material to prepare a second intermediate structure; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare the inorganic bonding layer. The inorganic material particles may comprise a material selected from the group consisting of: glass, alumina (Al2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

Description

INORGANIC LIGHT CONVERSION MODULETECHNICAL FIELD

[0001] The present disclosure relates to electrophoretic deposition of inorganic materials, including inorganic bonding materials such as glass, alumina (AI2O3), and / or Yttrium Aluminum Garnet (YAG) particles, and / or materials for high thermal conductivity such as boron nitride and aluminum nitride, onto non-conductive substrates, preferably thin non-conductive substrates, preferably a light conversion module such as a thin garnet plate, followed by burn-out of organics after which an inorganic bond is established by melting or sintering or densifying the materials, namely particles. In this regard, a fully inorganic attachment of the light conversion module, for example, a thin garnet plate, to another surface is achieved. The present disclosure also relates generally to light conversion modules including such electrophoretically-deposited inorganic bonding materials for phosphor-converted light emitting diodes (pc-LEDs), and devices and arrays including the same. The electrophoretically-deposited inorganic bonding materials are densely-packed onto the non-conductive substrates.BACKGROUND

[0002] Semiconductor light-emitting devices or optical power emitting devices (such as devices that emit ultraviolet (UV) or infrared (IR) optical power), including light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, and edge emitting lasers, are among the most efficient light sources currently available. Due to their compact size and lower power requirements, for example, semiconductor light or optical power emitting devices (referred to herein as LEDs for simplicity) are attractive candidates for light sources, such as camera flashes, for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for other applications, such as for automotive lighting, torch for video, and general illumination, such as home, shop, office and studio lighting, theater / stage lighting and architectural lighting.

[0003] High-intensity / brightness light emitting devices capable of operation across the visible spectrum include Group lll-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, alsoreferred to as Ill-nitride materials. Typically, Ill-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a growth substrate such as a sapphire, silicon, silicon carbide, Ill-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. Sapphire is often used as the growth substrate due to its wide commercial availability and relative ease of use. The stack grown on the growth substrate typically includes one or more n-type layers doped with, for example, Si, formed over the substrate, a light emitting or active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region.

[0004] Phosphor converted LEDs (pc-LEDs) include a converter layer, e.g., a phosphor layer on an LED pump. The phosphor layer absorbs energy and converts an entering wavelength to a lower-energy wavelength. For example, the phosphor layer down-converts high energy LED light into a more desirable color spectrum. In practice, the phosphor layer composition and structure are chosen to meet desired performance criteria. Reliability is a requirement for pc-LEDs. Demand for pc-LEDs operating at high power levels has been on the rise, which in turn presents a need for pc-LED materials to operate at high temperatures while maintaining good stability.

[0005] The presence of organic materials in bonding materials between phosphor converted LEDs (pc-LEDs) and a converter layer renders them prone to degradation under at high optical flux and temperature, and hence can lead to premature reliability failures of pc-LEDs.

[0006] There is a need to develop methods for depositing thin layers of densely packed inorganic bonding particles, e.g., glass, alumina (AI2O3), and / or Yttrium Aluminum Garnet (YAG) particles, and / or boron nitride or aluminum nitride, and for preparing pc-LEDs and the like that can overcome reliability shortcomings at extreme operating conditions.SUMMARY

[0007] Provided herein are bonding layers of LEDs, and LED devices and arrays and light sources including the same, and methods of making the same. In one or more aspects, layers, inorganic bonding layers are deposited on thin non- conductive substrates, for example, light conversion modules, preferably garnetplates, by electrophoretic deposition. Preferably, these layers are thin and densely packed. Thin, densely packed bonding layers have advantages, for instance, with respect to control of scattering and better thermal conductivity as compared to traditionally-prepared bonding layers based upon silicones.

[0008] In an aspect, methods of preparing an inorganic bonding layer comprise: conducting electrophoresis to deposit particles of an inorganic material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; fixing the particles of the inorganic material with a binder material to prepare a second intermediate structure; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare the inorganic bonding layer.

[0009] Another aspect provides methods of making an inorganic light conversion module for a light emitting diode (LED) comprising: conducting electrophoresis to deposit glass particles in a suspension composition onto a polycrystalline ceramic plate of a phosphor material to prepare a first intermediate structure; fixing the glass particles with a binder material derived from a sol-gel material to prepare a second intermediate structure; exposing the second intermediate structure to a removal treatment to remove any organic materials of at least the suspension composition and the sol-gel material; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare an inorganic bonding layer of melted glass particles.

[0010] A further aspect is an inorganic light conversion module for a light emitting diode (LED) comprising: a plurality of electrophoretically-deposited inorganic material particles in combination with a binder material; and a thin non-conductive substrate.

[0011] Another aspect is a light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the inorganic light conversion module to any embodiment herein affixed to the mesas by an inorganic bonding layer comprising the plurality of electrophoretically-deposited inorganic material particles prepared with the binder material.

[0012] In another aspect, a method of manufacturing a light emitting source comprises: affixing the inorganic light conversion module according to any embodiment herein on a light emitting diode (LED) or an array of LEDs.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. The line drawings herein are not to scale.

[0014] FIGS. 1A, 1 B, and 1 C provide schematic views illustrating in crosssection a portion of an electrophoretic deposition (EPD) cell without (FIG. 1 A) and with (FIGS. 1 B and 1 C) a thin non-conducting substrate positioned therein;

[0015] FIG. 2 is a section schematic view of a light conversion module according to an embodiment;

[0016] FIGS. 3-4 are cross-section schematic views of light emitting diode (LED) arrays according to various embodiments;

[0017] FIGS. 5A-5G are cross-section schematic views of a light conversion module preparation into a LED array during operations of a method of making the same using electrophoretic deposition according to an embodiment;

[0018] FIG. 6 is a process flow diagram of the method of making a converter component according to FIGS. 5A-5G;

[0019] FIG. 7 schematically illustrates an exemplary headlight illumination system comprising converter components and / or converter layers according to embodiments herein; and

[0020] FIGS. 8A-8G are cross-section schematic views of a light conversion module preparation into a LED array during operations of a method of making the same using electrophoretic deposition according to an embodiment.DETAILED DESCRIPTION

[0021] Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

[0022] The term "substrate" as used herein according to one or more embodiments refers to a structure, intermediate or final, having a surface, or portion of a surface, upon which a process acts. In addition, reference to a substrate in some embodiments also refers to only a portion of the substrate, unless the context clearly indicates otherwise. Further, reference to depositing on a substrate according to some embodiments includes depositing on a bare substrate, or on a substrate with one or more films or features or materials deposited or formed thereon.

[0023] In one or more embodiments, the "substrate" means any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. A “device substrate” is a substrate of a final product or device. In exemplary embodiments, a substrate surface on which processing is performed includes materials such as silicon, silicon oxide, silicon on insulator (SOI), strained silicon, amorphous silicon, doped silicon, carbon doped silicon oxides, germanium, gallium arsenide, glass, sapphire, and any other suitable materials such as metals, metal nitrides, Ill-nitrides (e.g., GaN, AIN, InN and alloys), metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, light emitting diode (LED) devices, including uLED devices. Substrates in some embodiments are exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and / or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in some embodiments, any of the film processing steps disclosed are also performed on an underlayer formed on the substrate, and the term "substrate surface" is intended to include such underlayer as the context indicates.

[0024] Methods of depositing thin films include but are not limited to: sputter deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced atomic layer deposition (PEALD), plasma enhanced chemical vapor deposition (PECVD), and combinations thereof.

[0025] Reference to LED refers to a light emitting diode that emits light when current flows through it. In one or more embodiments, for example, head lamps, the LEDs herein have one or more characteristic dimensions (e.g., height, width, etc.) in a range of greater than or equal to 1 micrometer to less than or equal to 300 micrometers, and all values and subranges therebetween. In one or embodiments, one or more dimensions of height and width have values in a range of 40 to 300 micrometers. Reference herein to micrometers allows for variation of ±1 -5%. In some instances, the LEDs are referred to as micro-LEDs (uLEDs or pLEDs), referring to a light emitting diode having one or more characteristic dimensions (e.g., height, width, etc.) on the order of micrometers or tens of micrometers.

[0026] Converter layers, namely phosphor layers absorb energy, converting an entering wavelength to a lower-energy higher wavelength. Herein, in one or more aspects, the converter layers comprise phosphor particles as down-converter material. Other down-converter materials may be semiconductor nanoparticles (quantum dots), which may be used in combination with phosphor particles.

[0027] The present disclosure includes preparation of an inorganic bonding layer, e.g., a glass layer, on a thin substrate, which can be glass-based, sapphire, garnet, alumina, or another material, e.g., a thin, non-conducting material. A densely- packed bonding layer is applied by electrophoretic deposition on a thin non-conductive substrate, preferably followed by burn-out of all organics after which an inorganic bond is established by a preparation heat treatment, which in one or more embodiments, includes: melting or sintering or densifying the particles to prepare the layer. The preparation heat treatment is generally conducted such that the inorganic bonding layer is translucent or transparent. In generally, the preparation heat treatment is conducted at temperatures that do not compromise the integrity of the underlying substrates and / or LEDs.

[0028] Reference to a “non-conductive” substrate means that the substrate is effective as an insulator. Many ceramics and polymers are considered insulators, whereas metals and semiconductor materials are not. In one or more aspects, a non- conductive substrate has a conductivity of below 1010(Ohm.m)-1.

[0029] Reference to a “densely-packed” particle layer means that the layer has a desired maximum particle volume fraction, depending on polydispersity and shape.In one or more aspects, a densely-packed particle layer has a maximum particle volume fraction value of approximately 50% in volume, and preferably for monodisperse spheres, the value is around 64% (random close packing).

[0030] There is a need for developing methods to deposit thin layers of densely packed inorganic bonding particles, e.g., glass particles, onto substrates, e.g., nonconducting substrates for use in LEDs, in particular uLEDs. Inorganic bonding yields bonds between materials that can be used at high temperatures and or light intensities. If the bonding between two materials would include organic materials decomposition by light or temperature, such can disadvantageously lead to browning or other failures of the binding with respect to LED and / or laser light application / device architectures.

[0031] Silicones are typically-used adhesive for LED applications. Although under many circumstances they function well, silicones contain organic methyl and often also phenyl groups that can degrade leading to failures. As for eliminating the presence of organic materials, an inorganic bond is suitable, desirably to be applied as a very thin layer. An application technique for applying very thin layers of glass particles that can be melted or alumina particles that can be sintered and / or densified is electrophoretic deposition. The particle layer will have a high packing density. Electrophoretic deposition (EPD) is normally performed on conductive substrates. As identified herein, if the substrate is sufficiently thin, and the conductivity of the EPD suspension is low, EPD can be carried out on an insulating sheet or plate, attached to an electrode.

[0032] Electrophoretic deposition (EPD) is a way to apply densely packed particles layers onto a substrate. Traditionally, EPD has been a method for depositing thin layers suitable only for conducting substrates. It was surprisingly found that electrophoretic deposition is an efficient way to apply bonding layers, namely inorganic bonding layers, onto thin non-conducting substrates. FIGS. 1A-1 C provide schematic views illustrating in cross-section a portion of an EPD cell 1 without (FIG. 1A) and with (FIGS. 1 B and 1 C) a thin non-conducting substrate 20 positioned therein. In FIGS. 1A-1 C, a first electrode 21 a and a second electrode 21 b of the EPD cell are separated by a distance “d”. In use, an electric field (E) (V / d) is applied to the cell. The first electrode 21 a is subjected to a first voltage Vi and the second electrode 21 bis subjected to a second voltage V2. A potential difference 2, e.g., delta voltage (AV), which is |Vi - V2I, is equal to E * d. Turing to FIG. 1A, the EPD cell is a capacitor in the absence of electrochemical reactions which charges when a potential difference is applied. In FIG. 1 B, upon introduction of the thin non-conducting substrate 20 having a thickness di into the cell, the distance between the first and second electrodes 21 a and 21 b becomes d2. The thickness di is negligible compared to d2. As shown in FIG. 10, which is a simplified version of FIG. 1 B, because the substrate thickness is thin / negligible, any potential drop over this thickness is insignificant, even if dielectric constants differ. The presence of a thin, non conductive substrate with thickness di does not change the properties of the capacitor much, the difference between d, which is for instance 0.5-1 cm, and d2 is negligible. In some aspects, di is in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, including all values and subranges therebetween, including greater than or equal to 15 micrometers to less than or equal to 100 micrometers, and greater than or equal to 20 micrometers to less than or equal to 50 micrometers.

[0033] A comparison between current during electrophoretic deposition of a YAG phosphor for a conducting surface (stainless steel) and deposition on thin (170 pm) glass or (100 pm) alumina (non-conducting) attached to a stainless steel electrode was conducted. The initial current was the same for stainless steel versus the non-conducting substrates, the current decrease as a function of time was much stronger for the non-conducting substrates.

[0034] While EPD is standard technology on a conducting substrate, for thin substrates and using suspensions of low conductivity, it was unexpectedly found that electrophoretic deposition is an efficient way to apply inorganic bonding layers. Some applications include deposition of a bonding layer onto a sintered ceramic plate like a doped yttrium aluminum garnet.

[0035] A “thin” substrate as used herein has a thickness that does not noticeably change potential drop properties of an EPD cell.

[0036] Devices herein include inorganic bonding layers that comprise electrophoretically-deposited inorganic bonding particles. Electrophoretically- deposited bonding particles are densely-packed and are just a few particles, for example 2-3 particles, thick. In some aspects, the inorganic bonding layers comprisea thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers, and all values and sub-ranges therebetween. The inorganic bonding layers are prepared on thin non-conductive substrates, namely converter devices and layers, to prepare inorganic light conversion modules, which are then affixed to light emitting diodes and arrays of the same.

[0037] FIG. 2 is a cross-section schematic view of an inorganic light conversion module according to an embodiment. The inorganic light conversion module 11 comprises a combination 12 of a plurality of inorganic material particles 14 and a binder material 16 on a thin, non-conducting substrate 20. The plurality of inorganic material particles 14, e.g., glass particles, is electrophoretically-deposited onto the substrate 20. The binder material 16 is among the inorganic material particles 14.

[0038] FIG. 3 is a cross-section schematic view of a light emitting diode (LED) array according to an embodiment. The LED array 30 comprises a thin, nonconducting substrate 20 affixed to a device substrate 22 by an inorganic bonding layer 18. The inorganic bonding layer 18 is a result of a melting heat treatment of the combination 12 of the plurality of inorganic material particles 14 and the binder material 16 of FIG. 2.

[0039] FIG. 4 is a cross-section schematic view of a light emitting diode (LED) array according to FIG. 3 with the addition of a mirror layer 90. The LED array 31 comprises the thin, non-conducting substrate 20 affixed to the device substrate 22 by the inorganic bonding layer 18. The inorganic bonding layer 18 is a result of a melting heat treatment of the combination 12 of the plurality of inorganic material particles 14 and the binder material 16 of FIG. 2. The mirror layer 90 is on the thin, nonconducting substrate 20 on a surface opposite the inorganic bonding layer 18.

[0040] Generally, aspect herein include: an inorganic light conversion module for a light emitting diode (LED) comprising: a plurality of electrophoretically-deposited inorganic material particles in combination with a binder material; and a thin non- conductive substrate.

[0041] In one or more embodiments, the inorganic material particles comprise a material selected from the group consisting of: glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

[0042] In one or more embodiments, the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers.

[0043] In one or more embodiments, the inorganic material particles are densely-packed on the thin non-conductive substrate.

[0044] In one or more embodiments, a combination of the inorganic material particles have an average thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers, and all values and sub-ranges therebetween.

[0045] In one or more embodiments, the thin non-conductive substrate comprises a ceramic or a glass.

[0046] In one or more embodiments, the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material, which preferably is a garnet material, which preferably comprises: a Ce(lll) doped garnet material ((Mli_x_yMllxMil|y)3(Ali_zMlvz)50 i2 with M1is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr, Ce, Er, Nd, or Eu, and MIVis Gd or Sc, wherein with 0 < x < I ; 0 < y<0, 1 und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials ( / WSi2O2N2), wherein M= alkaline earth.

[0047] In some embodiments, the binder material comprises inorganic binder particles. In some embodiments, the inorganic binder particles comprise silica.

[0048] In one or more embodiments, the inorganic light conversion module is completely inorganic.

[0049] Other aspects include: a light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the inorganic light conversion module of any embodiments herein affixed to the mesas by an inorganic bonding layer comprising the plurality of electrophoretically-deposited inorganic material particles prepared with the binder material. The mesas may have at least one characteristic dimension of greater than or equal to 1 micrometer less than or equal to 300 micrometers. In some embodiments, the LED array further comprises a phosphor layer disposed on the mesas to which the inorganic light conversion module is affixed by the inorganic bonding layer.

[0050] In one or more embodiments, the LED arrays herein are effective in an automotive head lamp system.

[0051] In one or more embodiments, the LED arrays herein further comprise a mirror layer on the inorganic light conversion module on a surface opposite the inorganic bonding layer.

[0052] In one or more embodiments, the LED arrays herein are effective in a laser projection system.

[0053] In some embodiments, the LED arrays are completely inorganic.

[0054] Another aspect is a light source comprising: any of the LED arrays herein attached to a device substrate. In some embodiments, one or groups of light emitting diodes (LEDs) of the LED array are individually addressable.

[0055] In embodiments, phosphor particles of the pc-LEDs may be composed of Y3AlsOi2:Ce3+. The phosphor particles may be an amber to red emitting rare earth metal-activated oxonitridoalumosilicate of the general formula (Cai-x-y-zSrxBayMgz)i- n(Ah-a+ Ba)Sii- N3- O :REn wherein 0<x<1 , 0<y<1 , 0<z<1 , 0<a<1 , 0<b<1 and 0.002<n<0.2, and RE may be selected from europium(ll) and cerium(lll).

[0056] In other embodiments, the phosphor particles may include aluminum garnet phosphors with the general formula (Lui-x-y-a-bYxGdy)3(Ali-zGaz)50i2: CeaPrb, wherein 0<x<1 , 0<y<1 , 0<z<0.1 , 0<a<0.2 and 0<b<0.1 , such as Lu3AlsOi2:Ce3+and Y3AlsOi2:Ce3+, which emits light in the yellow-green range; and (Sri-x-yBaxCay)2-zSi5-aAlaN8-aOa:Euz2+, wherein 0<a<5, 0<x<1 , 0<y<1 , and 0<z<1 such as Sr2Si5Ns:Eu2+, which emits light in the red range. Other green, yellow and red emitting phosphors may also be suitable, including (Sri-a-bCa Bac)SixNyOz:Eua2+; (a=0.002-0.2, b=0.0- 0.25, c=0.0-0.25, x=1 .5-2.5, y=1 .5-2.5, z=1 .5-2.5) including, SrSi2N2O2:Eu2+; (Sn-u-v- xMguCavBax)(Ga2-y-zAlylnzS4):Eu2+including, for example, SrGa2S4:Eu2+; Sn- xBaxSiO4:Eu2+; and (Cai-xSrx)S:Eu2+wherein 0<x<1 including, CaS:Eu2+and SrS:Eu2+. Other suitable phosphors include, CaAISiN3:Eu2+,(Sr,Ca)AISiN3:Eu2+, and (Sr, Ca, Mg, Ba, Zn)(AI, B, In, Ga)(Si, Ge)N3:Eu2+.

[0057] In other embodiments, the phosphor particles may also have a general formula (Sri-a- Ca BacMgdZne)SixNyOz:Eua2+, wherein 0.002<a<0.2, 0.0<b<0.25, 0.0<c<0.25, 0.0<d<0.25, 0.0<e<0.25, 1.5<x<2.5, 1.5<y<2.5 and1 .5<z<2.5. The phosphor particles may also have a general formula of MmAaBbOoNmZz where anelement M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or more tetravalent elements, O is oxygen that is optional and may not be in the phosphor plate, N is nitrogen, an element Z that is an activator, n=2 / 3m+a+4 / 3b-2 / 3o, wherein m, a, b can all be 1 and o can be 0 and n can be 3. M is one or more elements selected from Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium) and Zn (zinc), the element A is one or more elements selected from B (boron), Al (aluminum), In (indium) and Ga (gallium), the element B is Si (silicon) and / or Ge (germanium), and the element Z is one or more elements selected from rare earth or transition metals. The element Z is at least one or more elements selected from Eu (europium), Mg (manganese), Sm (samarium) and Ce (cerium). The element A can be Al (aluminum), the element B can be Si (silicon), and the element Z can be Eu (europium).

[0058] The phosphor particles may also be an Eu2+activated Sr — SiON having the formula (Sri-a-bCabBac)SixNyOx:Eua, wherein a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1 .5-2.5, y=1 .5-2.5.

[0059] The phosphor particles may also be a chemically-altered Ce: YAG (Yttrium Aluminum Garnet) phosphor that is produced by doping the Ce: YAG phosphor with the trivalent ion of praseodymium (Pr). The phosphor particles may include a main fluorescent material and a supplemental fluorescent material. The main fluorescent material may be a Ce: YAG phosphor and the supplementary fluorescent material may be europium (Eu) activated strontium sulfide (SrS) phosphor (“Eu:SrS”). The main fluorescence material may also be a Ce: YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a mixed ternary crystalline material of calcium sulfide (CaS) and strontium sulfide (SrS) activated with europium ((CaxSri_x)S:Eu2+). The main fluorescent material may also be a Ce:YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a nitrido-silicate doped with europium. The nitrido-silicate supplementary fluorescent material may have the chemical formula (Sri-x-y-zBaxCay)2Si5N8:Euz2+where 0<x, y<0.5 and 0<z<0.1.

[0060] In embodiments, the phosphor particles may include strontium-lithium- aluminum: europium (II) ion (SrLiAh N4:Eu2+) class (also referred to as SLA), includingMUAI3N4: Eu2+(M = Sr, Ba, Ca, Mg). In a specific embodiment, the phosphor particles may be selected from the following group of luminescent material systems: MLiAhlX Eu (M=Sr, Ba, Ca, Mg), M2SiO4:Eu (M=Ba, Sr, Ca) , MSei-xSx:Eu (M=Sr, Ca, Mg), MSr2S4:Eu (M=Sr, Ca), M2SiF6:Mn (M=Na, K, Rb), M2TiF6:Mn (M=Na, K, Rb), MSiAIN3:Eu (M=Ca, Sr), M8Mg(SiO4)4CI2:Eu (M=Ca, Sr), M3MgSi2O8:Eu (M=Sr, Ba, Ca), MSi2O2N2:Eu (M=Ba, Sr, Ca), M2Si5-xAlxOxN8-x:Eu (M=Sr, Ca, Ba). However, other systems may also be of interest and may be protected by a coating. Also combinations of particles of two or more different luminescent materials may be applied, such as e.g. a green or a yellow luminescent material in combination with a red luminescent material.

[0061] In embodiments, the phosphor particles may include a blend of any of the above-described phosphors.

[0062] Direction, beam width, and beam shape of light emitted from each LED can be modified by optical elements. The optical elements a single optical element or a multiple optic elements. Optical elements can include converging or diverging lenses, aspherical lens, Fresnel lens, or graded index lens, for example. Other optical elements such as mirrors, beam diffusers, filters, masks, apertures, collimators, or light waveguides are also included. Optical elements can be positioned at a distance from the LEDs that allows receipt and redirection of light from multiple LEDs. Alternatively, optical elements can be set atop each LED to individually guide, focus, or defocus emitted LED light. Optical elements can be directly attached to the LEDs, attached to LEDs via a transparent interposer or plate, or held at a fixed distance from LEDs by surrounding substrate attachments.

[0063] FIGS. 5A-5G are cross-section schematic views of a light conversion module preparation into a LED array during operations of a method of making the same using electrophoretic deposition according to an embodiment, FIGS. 8A-8G are cross-section schematic views of a light conversion module preparation into a LED array during operations of a method of making the same using electrophoretic deposition according to another embodiment, and FIG. 6 is a process flow diagram of the method of making a converter component 600 according to both FIGS. 5A-5G or FIGS. 8A-8G.

[0064] To facilitate an EPD process on a non-conductive substrate, conductivity of a suspension composition is preferably very low and the substrate is thin. To make such a suspension composition, the particles to be deposited are dispersed in an apolar solvent. According to some embodiments, to obtain a colloidally stable suspension that can be manipulated in an electric field, a polymeric stabilizer and a charging agent are added. A conductivity of the suspension composition may be on the order of pS / cm, for instance in a range of 6-30 pS / cm. The apolar solvent generally has a low dielectric constant, and in such systems, no electrochemical reactions at the electrodes have been identified that regulate the current through the system during electrophoretic deposition. As a consequence, the electric field that is initially present if a voltage is applied, is determined by the geometry and dielectric constants. The strength of the field and the charge on the particles regulate the deposition, (e.g., FIGS. 1A, 1 B, 10), during deposition the current drops faster as charge generation at the electrode cannot occur. The substrate can be a ceramic material, for instance a garnet, like an Yttrium Aluminum Garnet (YAG) with a known light scattering or it can be an ultra-thin glass. Substrates can have a thickness of 200 pm and below, to for instance 40 pm or 20 pm or 10 pm. To give the particle layer some mechanical strength, sufficient for handling and to start subsequent processing an application of a sol-gel material can be performed, for instance by a dipcoating process. In case glass particles are deposited the substrate can be attached to another body at elevated temperature, depending on the melting point of the glass. Particles that can be sintered need a much higher temperature. The bonding material can be one or a combination of: a glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, or other inorganic compounds whereby after applying and after melting or sintering the layer will densify in a transparent material to bond the two materials together.

[0065] With reference to FIGS. 5A and 8A and FIG. 6, at operation 610, electrophoresis is conducted in a cell having a first electrode 21 a and a second electrode 21 b to deposit particles of an inorganic material, e.g., glass particles, onto a thin non-conductive substrate (thickness of substate(s) in FIGS. 5A-5G and FIGS. 8A- 8G are not to scale, they are enhanced for clarity). The substrate 20 is attached to a first electrode 21 b by suitable means, e.g., a tape or inserted into a holder, and makescontact with the second electrode 21 b (for illustration purposes only, either electrode can be used) at one side. With regard to FIG. 5A, a suspension composition comprises particles of an inorganic material 13 in a liquid carrier. With regard to FIG. 8A, a suspension composition comprises particles of an inorganic material 13 and non-meltable particles 15 in a liquid carrier.. In one or more embodiments, the liquid carrier is an apolar liquid, such as such as alkanes, or mixtures of alkanes commercially available as isopar or shellsol, and other materials such as a polymeric stabilizer, a poly(alkyl) methacrylate, and / or a charging agent, such as chrome- anthralinate. Upon application of an electrical potential to the first and second electrodes 21 a and 21 b, a plurality of particles 14 is formed on the substrate 20, which prepares a first intermediate structure.

[0066] At operation 620 of FIG. 6, and shown in FIGS. 5B and 8B, the substrate 20 having the plurality of inorganic material particles 14 is removed from the second electrode 21 b.

[0067] At operation 640a of FIG. 6, optionally, the substrate comprising the particles 14 fixed with the binder material 16, is subject to a removal treatment, e.g., by curing to remove any organic materials of the suspension composition. Possible organic residues, for instance resulting from the polymeric stabilizer in the suspension can be removed at high temperature only, or in combination with UV radiation or an oxygen (O2) plasma treatment. In one or more embodiments, the substrate is treated to remove organics.

[0068] At operation 630 of FIG. 6, and shown in FIGS. 5C and 80, the particles 14 are fixed to prepare a second intermediate structure. Fixing the particles 14 of the inorganic material comprises addition of a binder material, which is applied by, for example, a sol-gel coating. FIGS. 50 and 80 show fixing the particles with a binder by way of sol-gel coating 51 for illustration purposes.

[0069] A sol-gel coating process can be carried out as a dip-coating process into a solution of sol-gel material. The material accumulates in the “necks” between particles and particles and surface, which is depicted as the binder material 16 in FIGS. 5D and 8D. A goal is to create enough strength for handling and the next step(s). Upon fixing of the particles 14 with a binder material 16 derived from the solgel material, a second intermediate structure is prepared depicted in FIGS. 5D and8D. A non-limiting example of a sol-gel material includes: TEOS [Tetraethyl orthosilicate: Si(OC2H5)4; EtOH [ethanol]; HCI [hydrochloric acid], which is subjected to a duration hydrolysis and dilution in an alcohol. The hydrolysis reaction is carried out to form silanols, which can subsequently react to form siloxanes. The TEOS (tetra-ethoxysilane) is ultimately converted to SiO2, which is an exemplary binder material.

[0070] At operation 640b of FIG. 6, and shown in FIGS. 5D and 8D, the second intermediate structure comprising the particles 14 fixed with the binder material 16, is optionally subject to a removal treatment, e.g., by curing, to remove of any of the organic materials of the suspension composition and / or the sol-gel material. Possible organic residues, for instance resulting from the polymeric stabilizer in the suspension can be removed at high temperature only, or in combination with UV radiation or an oxygen (O2) plasma treatment. In one or more embodiments, the second intermediate structure is treated to remove organics.

[0071] At operation 650 of FIG. 6, and shown in FIGS. 5E-5F and FIGS. 8E-8F, a device substrate 22 is brought near (FIGS. 5E and FIG. 8E) and into contact (FIGS. 5F and 8F) with the combination 12 of particles 14 and binder material 16. Upon contact shown in FIGS. 5F and 8F, a third intermediate structure is formed.

[0072] At operations 660-670 of FIG. 6, a preparation heat treatment is applied to the third intermediate structure to melt or sinter or densify the inorganic particles 14. Generally, the structure treated until a translucent or transparent layer of particles is prepared. FIG. 5G shows a final device, which is the same as FIG. 3, where and LED array comprises the thin, non-conducting substrate 20 affixed to the device substrate 22 by an inorganic bonding layer 18. FIG. 8G shows a final device, whose inorganic bonding layer 18 includes particles 15 of the non-meltable particles among the layer prepared by the treatment.

[0073] Thereafter, at operation 680 of FIG. 6, any further processing of the structure may optionally be conducted to prepare the structure for final applications. Further processing includes but is not limited to deposition of a mirror layer onto the structure. Generally, the structure may be treated so that the surface is smooth enough to accept the mirror layer. In addition, additional layers, e.g., metal, may bedeposited to facilitate good adhesion of the mirror. Further processing also includes but is not limited to position of optical features onto the structure.

[0074] In summary, an aspect comprises methods that comprise: conducting electrophoresis to deposit particles of an inorganic material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; fixing the particles of the inorganic material with a binder material to prepare a second intermediate structure; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare the inorganic bonding layer.

[0075] In one or more embodiments the inorganic bonding layer is effective to affix the thin non-conductive substrate to the device substrate.

[0076] In one or more embodiments, the preparation heat treatment is conducted such that the inorganic bonding layer is translucent or transparent.

[0077] In some embodiments, the particles of the inorganic material are densely-packed on the first intermediate structure.

[0078] Some embodiments provide that upon exposure to the preparation heat treatment, the particles of the inorganic material yield a continuous layer of the inorganic bonding layer on the thin non-conductive substrate.

[0079] In one or more embodiments, the conducting of the electrophoresis comprises: positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the inorganic material dispersed in an apolar liquid; and applying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the inorganic material deposits onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

[0080] In one or more embodiments, the suspension composition further comprises: a polymeric stabilizer and / or a charging agent. In detailed embodiments, the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

[0081] In some embodiments, the fixing of the particles of the inorganic material comprises: conducting a sol-gel process by exposing the first intermediate structure toa solution of a sol-gel material to prepare a second intermediate structure, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material.

[0082] In one or more embodiments, the methods further comprise removing of any of organic materials of at least the suspension composition and the sol-gel material by exposing the second intermediate structure to UV radiation or an oxygen plasma treatment.

[0083] In one or more embodiments, the methods further comprise removing any organic materials of at least the suspension composition and the sol-gel material by exposing the second intermediate structure to a removal heat treatment.

[0084] In one or more embodiments, the methods further comprise depositing a mirror material on the thin non-conductive substrate on a surface opposite the inorganic bonding layer.

[0085] Another aspect is a method of making an inorganic light conversion module for a light emitting diode (LED) comprising: conducting electrophoresis to deposit glass particles in a suspension composition onto a polycrystalline ceramic plate of a phosphor material to prepare a first intermediate structure; fixing the glass particles with a binder material derived from a sol-gel material to prepare a second intermediate structure; exposing the second intermediate structure to a removal treatment to remove any organic materials of at least the suspension composition and the sol-gel material; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare an inorganic bonding layer of melted glass particles.

[0086] In an aspect, a method of manufacturing a light emitting source comprises: affixing the inorganic light conversion module according to any embodiments herein on a light emitting diode (LED) or an array of LEDs.APPLICATIONS

[0087] The inorganic light conversion modules and / or a light emitting diode (LED) arrays can be used in various applications, including connecting various typesof materials used in high power LED devices and laser light (blue) engine devices, whereby high light power intensities are being used.

[0088] As an example the invention is used to bond sapphire materials, single crystal AI2O3 or polycrystalline AI2O3, to a ceramic converter material like a ceria doped garnet (Y,Gd,Lu)3(AI,Ga)sOi2. The latter is used to convert blue light into a green-yellow light. The ceramic converter is applied onto a carrier material, usually the sapphire, and under high power demands, need to withstand high light intensity and temperature.

[0089] This module of a converter onto sapphire can be used in architectures whereby the (laser-) light hits this piece of device in a reflective mode, where a mirror is used, or in a transmissive mode.

[0090] Instead of using sapphire, also other materials like YAG (Y3AI5O12), AI2O3, a matrix of YAG in AI2O3 or AI2O3 in YAG can be used. As also other transparent or translucent materials, whereby the optical properties define the architecture of the light engine (like a high power LED) can be met.

[0091] Generally, a converter, which is based upon Y3O5AI12, is used whereby the properties can be tuned with Gd, Lu, Ga and other elements. The ceria is used as the activator for the converter. However, same kind of construction be made using ceramics wafers based upon red phosphor BSSN:E or CSSN:E and the like.

[0092] FIG. 7 schematically illustrates an exemplary headlight illumination system 1000 utilizing LEDs disclosed herein. The headlight illumination system 1000 comprises an LED illumination array and lens system 1002 in electrical communication with an LED driver 1004. The headlight illumination system 1000 also comprises a controller 1006, such as a microprocessor. The controller 1006 is coupled to the LED driver 1004. The controller 1006 may also be coupled to one or more auxiliary components 1008 and sensors 1010 associated with the headlights, and operate in accordance with instructions and profiles stored in memory 1012.

[0093] Sensors 1010 may include, for example, positional sensors (e.g., a gyroscope and / or accelerometer) and / or other sensors that may be used to determine the position, speed, and orientation of system 1000. The signals from the sensors 1010 may be supplied to the controller 1006 to be used to determine the appropriate course of action of the controller 1006 (e.g., which LEDs are currently illuminating atarget and which LEDs will be illuminating the target a predetermined amount of time later).

[0094] In operation, illumination from some or all of the pixels of the LED array in 1002 may be adjusted - deactivated, operated at full intensity, or operated at an intermediate intensity. As noted above, beam focus or steering of light emitted by the LED array in 1002 can be performed electronically by activating one or more subsets of the pixels, to permit dynamic adjustment of the beam shape without moving optics or changing the focus of the lens in the lighting apparatus.

[0095] LED illumination arrays and lens systems such as described herein may support various other beam steering or other applications that benefit from finegrained intensity, spatial, and temporal control of light distribution. These applications may include, but are not limited to, precise spatial patterning of emitted light from pixel blocks or individual pixels. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and / or environmentally responsive. The light emitting pixel arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. Associated optics may be distinct at a pixel, pixel block, or device level. An example light emitting pixel array may include a device having a commonly controlled central block of high intensity pixels with an associated common optic, whereas edge pixels may have individual optics. In addition to flashlights, common applications supported by light emitting pixel arrays include video lighting, camera flashes, architectural and area illumination, and street lighting.

[0096] In some embodiments, each LED device in a light source array can be separately controlled, while in other embodiments groups of LEDs can be controlled as a block. In still other embodiments, both single LEDs and groups of LEDs can be controlled. To reduce overall data management requirements, control can be limited to on / off functionality or switching between relatively few light intensity levels. In other embodiments, continuous changes in lighting intensity are supported. Both individual and group level control of light intensity is contemplated. In one embodiment, overlapping or dynamically selected zones of control are also possible, with for example, overlapping groups of light emitters in the array being separately controllable despite having common LEDs depending on lighting requirements. In one embodiment, intensity can be separately controlled and adjusted by settingappropriate ramp times and pulse width for each LED using a pulse width modulation. This allows staging of LED activation to reduce power fluctuations, and to provide superior luminous intensity control.

[0097] Programmable light emitting arrays such as disclosed herein may also support a wide range of applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but is not limited to, precise spatial patterning of emitted light from blocks or individual LEDs. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and / or environmentally responsive. In some embodiments, the light emitting arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communications. Associated optics may be distinct at single or multiple LED level. An example light emitting array may include a device having a commonly controlled central block of high intensity LEDS with an associated common optic, whereas edge positioned LEDs may have individual optics. Common applications supported by light emitting LED arrays include camera or video lighting, architectural and area illumination, and street lighting.

[0098] Programmable light emitting arrays may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, light emitting arrays may be used to project media facades for decorative motion or video effects. In conjunction with tracking sensors and / or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct LEDs may be used to adjust the color temperature of lighting, as well as support wavelength specific horticultural illumination.

[0099] Street lighting is an important application that may greatly benefit from use of programmable light emitting arrays. A single type of light emitting array may be used to mimic various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected LEDs. In addition, street lighting costs may be lowered by adjusting light beam intensity or distribution according to environmental conditions or time of use. For example, light intensity and area of distribution may be reduced when pedestrians are not present. If LEDs are spectrally distinct, the colortemperature of the light may be adjusted according to respective daylight, twilight, or night conditions.

[0100] Programmable light emitting LEDs are also well suited for supporting applications requiring direct or projected displays. For example, automotive headlights requiring calibration, or warning, emergency, or informational signs may all be displayed or projected using light emitting arrays. This allows, for example, modifying directionality of light output from a automotive headlight. If a light emitting array is composed of a large number of LEDs or includes a suitable dynamic light mask, textual or numerical information may be presented with user guided placement. Directional arrows or similar indicators may also be provided.EMBODIMENTS

[0101] Various embodiments are listed below. It will be understood that the embodiments listed below may be combined with all aspects and other embodiments in accordance with the scope of the invention.

[0102] Embodiment (a) A method of preparing an inorganic bonding layer, the method comprising: conducting electrophoresis to deposit particles of an inorganic material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; fixing the particles of the inorganic material with a binder material to prepare a second intermediate structure; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare the inorganic bonding layer.

[0103] Embodiment (b) The method of embodiment (a), wherein the inorganic material particles comprise a material selected from the group consisting of: glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

[0104] Embodiment (c) The method of embodiment (a) or (b), wherein the inorganic bonding layer is effective to affix the thin non-conductive substrate to the device substrate.

[0105] Embodiment (d) The method of one of embodiments (a) to (c), wherein the preparation heat treatment is conducted such that the inorganic bonding layer is translucent or transparent.

[0106] Embodiment (e) The method of one of embodiments (a) to (d), wherein the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers.

[0107] Embodiment (f) The method of one of embodiments (a) to (e), wherein the particles of the inorganic material are densely-packed on the first intermediate structure.

[0108] Embodiment (g) The method of one of embodiments (a) to (f), wherein the inorganic bonding layer comprises a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

[0109] Embodiment (h.1) The method of one of embodiments (a) to (g), wherein the particles of the inorganic material upon exposure to the preparation heat treatment yield a continuous layer of the inorganic bonding layer on the thin non- conductive substrate.

[0110] Embodiment (h.2) The method one of embodiments (a) to (h.1 ), further comprising removing any organic materials of the suspension composition by exposing the substrate to heat or to UV radiation or an oxygen plasma treatment.

[0111] Embodiment (i) The method of one of embodiments (a) to (h.1 -h.2), wherein the conducting of the electrophoresis comprises: positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the inorganic material dispersed in an apolar liquid; and applying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the inorganic material deposits onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

[0112] Embodiment (j) The method of embodiment (i), wherein the suspension composition further comprises: a polymeric stabilizer and / or a charging agent.

[0113] Embodiment (k) The method of embodiment (j), wherein the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

[0114] Embodiment (I) The method of one of embodiments (a) to (k), wherein the fixing of the particles of the inorganic material comprises: conducting a sol-gel process by exposing the first intermediate structure to a solution of a sol-gel material to prepare a second intermediate structure, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material.

[0115] Embodiment (m) The method of embodiment (I) further comprising removing of any of organic materials of at least the suspension composition and the sol-gel material by exposing the second intermediate structure to UV radiation or an oxygen plasma treatment.

[0116] Embodiment (n) The method of embodiment (I) further comprising removing any organic materials of at least the suspension composition and the sol-gel material by exposing the second intermediate structure to a removal heat treatment.

[0117] Embodiment (o) The method of one of embodiments (a) to (n), wherein the thin non-conductive substrate comprises a ceramic or a glass.

[0118] Embodiment (p) The method of embodiment (o), wherein the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material, which is preferably a garnet material, which preferably comprises: a Ce(lll) doped garnet material ((Mli_x_yM"xMilly)3(Ali_zMlvz)50 i2 with M1is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr, Ce, Er, Nd, or Eu, and MIVis Gd or Sc, wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials ( / Vfei2O2N2), wherein M = alkaline earth.

[0119] Embodiment (q) The method of one of embodiments (a) to (p) further comprising depositing a mirror material on the thin non-conductive substrate on a surface opposite the inorganic bonding layer.

[0120] Embodiment (r) A method of making an inorganic light conversion module for a light emitting diode (LED) comprising: conducting electrophoresis to deposit glass particles in a suspension composition onto a polycrystalline ceramicplate of a phosphor material to prepare a first intermediate structure; fixing the glass particles with a binder material derived from a sol-gel material to prepare a second intermediate structure; exposing the second intermediate structure to a removal treatment to remove any organic materials of at least the suspension composition and the sol-gel material; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare an inorganic bonding layer of melted glass particles.

[0121] Embodiment (s) The method of embodiment (r), wherein the polycrystalline ceramic plate comprises: a Ce(lll) doped garnet material 1 is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr,wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (MSi2O2N2), wherein M= alkaline earth.

[0122] Embodiment (t) The method of embodiment (r) or (s), wherein the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

[0123] Embodiment (u) An inorganic light conversion module for a light emitting diode (LED) comprising: a plurality of electrophoretically-deposited inorganic material particles in combination with a binder material; and a thin non-conductive substrate.

[0124] Embodiment (v) The inorganic light conversion module of embodiment (u), wherein the inorganic material particles comprise a material selected from the group consisting of: glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

[0125] Embodiment (w) The inorganic light conversion module of embodiment (u) or (v), wherein the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers.

[0126] Embodiment (x) The inorganic light conversion module of one of embodiments (u) to (w), wherein the inorganic material particles are densely-packed on the thin non-conductive substrate.

[0127] Embodiment (y) The inorganic light conversion module of one of embodiments (u) to (x), wherein a combination of the inorganic material particles have an average thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

[0128] Embodiment (z) The inorganic light conversion module of one of embodiments (u) to (y), wherein the thin non-conductive substrate comprises a ceramic or a glass.

[0129] Embodiment (aa) The inorganic light conversion module of embodiment (z), wherein the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material, which preferably is a garnet material, which preferably comprises: a Ce(lll) doped garnet material is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr,wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (MSi2O2N2), wherein M= alkaline earth.

[0130] Embodiment (bb) The inorganic light conversion module of one of embodiments (u) to (aa), wherein the binder material comprises inorganic binder particles.

[0131] Embodiment (cc) The inorganic light conversion module of embodiment (bb), wherein the inorganic binder particles comprise silica.

[0132] Embodiment (dd) The inorganic light conversion module of one of embodiments (u) to (cc), which is completely inorganic.

[0133] Embodiment (ee) A light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the inorganic light conversion module of one of embodiments (u) to (dd) affixed to the mesas by an inorganic bonding layer comprising the plurality of electrophoretically- deposited inorganic material particles prepared with the binder material.

[0134] Embodiment (ff) The LED array of embodiment (ee), wherein the mesas have at least one characteristic dimension of greater than or equal to 1 micrometer less than or equal to 300 micrometers.

[0135] Embodiment (gg) The LED array of embodiment (ff) further comprising a phosphor layer disposed on the mesas to which the inorganic light conversion module is affixed by the inorganic bonding layer.

[0136] Embodiment (hh) The LED array of embodiment (gg) effective in an automotive head lamp system.

[0137] Embodiment (ii) The LED array of embodiment (ee) further comprising a mirror layer on the inorganic light conversion module on a surface opposite the inorganic bonding layer.

[0138] Embodiment (jj) The LED array of embodiment (ii) effective in a laser projection system.

[0139] Embodiment (kk) The LED array of one of embodiments (ee) to (jj), which is completely inorganic.

[0140] Embodiment (II) A light source comprising: the LED array of one of embodiments (ee) to (kk) attached to a device substrate.

[0141] Embodiment (mm) The light source of embodiment (II), wherein one or groups of light emitting diodes (LEDs) of the LED array are individually addressable.

[0142] Embodiment (nn) A method of manufacturing a light emitting source, the method comprising: affixing the inorganic light conversion module according to one of embodiments (u) to (dd) on a light emitting diode (LED) or an array of LEDs.

[0143] Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0144] Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood thatthe invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element / step not specifically disclosed herein.

Claims

What is claimed is:1 . A method of preparing an inorganic bonding layer, the method comprising: conducting electrophoresis to deposit particles of an inorganic material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; fixing the particles of the inorganic material with a binder material to prepare a second intermediate structure; contacting the second intermediate structure with a device substrate to prepare a third intermediate structure; and exposing the third intermediate structure to a preparation heat treatment to prepare the inorganic bonding layer.

2. The method of claim 1 , wherein the inorganic material particles comprise a material selected from the group consisting of: glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

3. The method of claim 1 , wherein the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, and / or the inorganic bonding layer comprises a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

4. The method of claim 1 , wherein the particles of the inorganic material are densely-packed on the first intermediate structure.

5. The method of claim 1 , wherein the particles of the inorganic material upon exposure to the preparation heat treatment yield a continuous layer of the inorganic bonding layer on the thin non-conductive substrate.

6. The method of claim 1 further comprising removing any organic materials of the suspension composition, preferably by exposing the substrate to heat or to UV radiation or an oxygen plasma treatment.

7. The method of claim 1 , wherein the conducting of the electrophoresis comprises:positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the inorganic material dispersed in an apolar liquid; and applying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the inorganic material deposits onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

8. The method of claim 7, wherein the suspension composition further comprises: a polymeric stabilizer and / or a charging agent, and optionally, the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

9. The method of claim 1 , wherein the fixing of the particles of the inorganic material comprises: conducting a sol-gel process by exposing the first intermediate structure to a solution of a sol-gel material to prepare a second intermediate structure, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material.

10. The method of claim 9 further comprising removing of any of organic materials of at least the suspension composition and the sol-gel material by exposing the second intermediate structure to UV radiation or an oxygen plasma treatment, or by exposing the second intermediate structure to a removal heat treatment.11 . The method of claim 1 , wherein the thin non-conductive substrate comprises a ceramic or a glass, preferably the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material.

12. The method of claim 1 further comprising depositing a mirror material on the thin non-conductive substrate on a surface opposite the inorganic bonding layer.

13. An inorganic light conversion module for a light emitting diode (LED) comprising:a plurality of electrophoretically-deposited inorganic material particles in combination with a binder material; and a thin non-conductive substrate.

14. The inorganic light conversion module of claim 13, wherein the inorganic material particles comprise a material selected from the group consisting of: glass, alumina (AI2O3), Yttrium Aluminum Garnet (YAG), boron nitride, aluminum nitride, and combinations thereof.

15. The inorganic light conversion module of claim 13, wherein the thin non- conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, and / or a combination of the inorganic material particles has an average thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

16. The inorganic light conversion module of claim 13, wherein the inorganic material particles are densely-packed on the thin non-conductive substrate.

17. The inorganic light conversion module of claim 13, wherein the thin non- conductive substrate comprises a ceramic or a glass, preferably the thin non- conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material.

18. The inorganic light conversion module of claim 13, which is completely inorganic.

19. A light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the inorganic light conversion module of claim 13 affixed to the mesas by an inorganic bonding layer comprising the plurality of electrophoretically- deposited inorganic material particles prepared with the binder material.

20. The LED array of claim 19, wherein the mesas have at least one characteristic dimension of greater than or equal to 1 micrometer less than or equal to 300 micrometers.

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