Abstract:
A method for manufacturing optoelectronic devices comprising the steps of: providing a common growth substrate; forming a light-emitting epitaxy structure on the common growth substrate; forming a stripping layer on the light-emitting epitaxy structure; forming a solar cell epitaxy structure on the stripping layer; forming an adhesive layer on the solar cell epitaxy structure; proving a solar cell permanent substrate on the adhesive layer; and removing the stripping layer to form a light-emitting device and a solar cell device separately.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a method for manufacturing optoelectronic devices, and more particularly to form a light-emitting device and a solar cell device by using a common growth substrate. 
       BACKGROUND 
       [0002]    The light radiation theory of light-emitting device is to generate light from the energy released by the electrons moving between the n-type semiconductor layer and the p-type semiconductor layer. Because the light radiation theory of light-emitting device is different from the incandescent light which heats the filament, the light-emitting device is called a “cold” light source. 
         [0003]    The light-emitting device mentioned above may be mounted with the substrate upside down onto a submount via a solder bump or a glue material to form a light-emitting apparatus. Besides, the submount further comprises one circuit layout electrically connected to the electrode of the light-emitting device via an electrical conductive structure such as a metal wire. 
         [0004]    Moreover, the light-emitting device is more sustainable, longevous, light and handy, and less power consumption, therefore it is considered as a new light source for the illumination market. The light-emitting device applies to various applications like the traffic signal, backlight module, street light and medical instruments, and is gradually replacing the traditional lighting sources. 
       SUMMARY 
       [0005]    The present application provides a method for manufacturing optoelectronic devices comprising the steps of: providing a common growth substrate, wherein the common growth substrate having a first surface and a second surface; forming a light-emitting epitaxy structure on the first surface of the common growth substrate; forming a stripping layer on the second surface of the common growth substrate; forming a solar cell epitaxy structure on the stripping layer opposite to the common growth substrate; forming an adhesive layer on the solar cell epitaxy structure opposite to the stripping layer; proving a solar cell permanent substrate on the adhesive layer opposite to the solar cell epitaxy structure; and removing the stripping layer to form a light-emitting device and a solar cell device separately. 
         [0006]    The present application provides a method for manufacturing optoelectronic devices comprising the steps of: providing a common growth substrate; forming a light-emitting epitaxy structure on the common growth substrate; forming a stripping layer on the light-emitting epitaxy structure; forming a solar cell epitaxy structure on the stripping layer; forming an adhesive layer on the solar cell epitaxy structure; proving a solar cell permanent substrate on the adhesive layer; and removing the stripping layer to form a light-emitting device and a solar cell device separately. 
         [0007]    The present application provides a method for manufacturing optoelectronic devices comprising the steps of: providing a common growth substrate; forming a solar cell epitaxy structure on the common growth substrate; forming a stripping layer on the solar cell epitaxy structure; forming a light-emitting epitaxy structure on the stripping layer; forming an adhesive layer on the light-emitting epitaxy structure; proving a light-emitting device permanent substrate on the adhesive layer; and removing the stripping layer to form a light-emitting device and a solar cell device separately. 
         [0008]    The present application provides a method for manufacturing optoelectronic devices comprising the steps of: providing a common growth substrate, wherein the common growth substrate having a first surface and a second surface; forming a stripping layer on the first surface of the common growth substrate; forming a light-emitting epitaxy structure on the stripping layer; forming an adhesive layer on the light-emitting epitaxy structure; proving a light-emitting device permanent substrate on the adhesive layer; forming a solar cell epitaxy structure on the second surface of the common growth substrate; and removing the stripping layer to form a light-emitting device and a solar cell device separately. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The foregoing aspects and many of the attendant advantages of this application are more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0010]      FIG. 1A  through  FIG. 1H  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar cell device  200  in accordance with a first embodiment of the present application; 
           [0011]      FIG. 2A  through  FIG. 2D  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar cell device  200  in accordance with a second embodiment of the present application; 
           [0012]      FIG. 3A  through  FIG. 3H  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar cell device  200  in accordance with a third embodiment of the present application; 
           [0013]      FIG. 4A  through  FIG. 4D  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar cell device  200  in accordance with a fourth embodiment of the present application; 
           [0014]      FIG. 5  is a diagram showing the temperature for growing a light-emitting device  100  and a solar cell device  200  in accordance with a fifth embodiment of the present application; 
           [0015]      FIG. 6  is a schematic diagram of a backlight module device  600  in accordance with a sixth embodiment of the present application; 
           [0016]      FIG. 7  is a schematic diagram of an illumination device  700  in accordance with a seventh embodiment of the present application; and 
           [0017]      FIG. 8  is a schematic diagram of a solar cell module  800  in accordance with an eighth embodiment of the present application. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present application discloses a method for manufacturing optoelectronic devices. In order to make the illustration of the present application more explicit, the following description is stated with reference to  FIG. 1  through  FIG. 8 . 
         [0019]      FIG. 1A  through  FIG. 1D  are schematic diagrams showing the process flow for manufacturing a light-emitting structure  10  and a solar cell structure  20  in accordance with a first embodiment of the present application. As  FIG. 1A  shows, a common growth substrate  110  is provided for the epitaxial growth of epitaxial materials formed thereon, wherein the common growth substrate  110  having a first surface  110   a  and a second surface  110   b . The material of the common growth substrate  110  may be GaAs or Ge. A light-emitting epitaxy structure  120  is grown on the first surface  110   a  of the common growth substrate  110  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the light-emitting epitaxy structure  120  comprises a first conductivity type III-V group compound semiconductor layer, an active layer, and a second conductivity type III-V group compound semiconductor layer (not shown) stacked on the first surface  110   a  of the common growth substrate  110 . For example, the first conductivity type III-V group compound semiconductor layer is n-type AlGaInP series material, the active layer is AlGaInP series material, and the second conductivity type III-V group compound semiconductor layer is p-type AlGaInP series material. A stripping layer  130  is grown on the second surface  110   b  of the common growth substrate  110  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. The material of the stripping layer  130  may be AlAs or AlGaAs. A solar cell epitaxy structure  140  is grown on the stripping layer  130  opposite to the common growth substrate  110  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the solar cell epitaxy structure  140  may be a multiple junction solar cell epitaxy structure, which is a serial connection of three cells of GaInP/GaAs/Ge. A tunnel junction structure is disposed between two neighboring cells wherein every cell is formed of III-V group compound semiconductor (not shown). As  FIG. 1B  shows, an adhesive layer  150  is formed on the solar cell epitaxy structure  140  opposite to the stripping layer  130 , wherein the material of the adhesive layer  150  may be Al, Au, Pt, Zn, Ag, Ni, Ge, In, Sn, Ti, Pb, Cu, Pd, or alloys of the aforementioned metals. In another embodiment, the material of the adhesive layer  150  may be silver glue, spontaneous conductive polymer, polymer materials mixed with conductive materials, or anisotropic conductive film (ACF). A solar cell permanent substrate  160  is provided on the adhesive layer  150  opposite to the solar cell epitaxy structure  140 , wherein the material of the solar cell permanent substrate  160  may be germanium (Ge), copper (Cu), aluminum (Al), molybdenum (Mo), tungsten copper (CuW), silicon aluminum (SiAl), gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), silicon (Si), gallium nitride (GaN), aluminum nitride (AlN) or diamond-like carbon (DLC). A wet etching solution containing hydrofluoric acid or citric acid is used for removing the stripping layer  130 , then a light-emitting structure  10  as shown in  FIG. 1C  and a solar cell structure  20  as shown in  FIG. 1D  are formed separately. 
         [0020]      FIG. 1E  through  FIG. 1H  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar cell device  200  in accordance with the above mentioned embodiments of the present application. As  FIG. 1E  shows, a transparent conductive layer  121  is formed on the light-emitting epitaxy structure  120 , and a first electrode  122  is formed on the transparent conductive layer  121 . A second electrode  111  is formed on the second surface  110   b  of the common growth substrate  110 . Finally, dicing the transparent conductive layer  121 , the light-emitting epitaxy structure  120 , the common growth substrate  110 , and the second electrode  111  along a cutting line  170  to form a light-emitting device  100  as shown in  FIG. 1F . As  FIG. 1G  shows, an anti-reflective layer  142  is formed on a portion of the solar cell epitaxy structure  140 , and a first electrode  141  is formed on the remained portion of the solar cell epitaxy structure  140 . A second electrode  161  is formed on the solar cell permanent substrate  160  opposite to the adhesive layer  150 . Finally, dicing the anti-reflective layer  142 , the solar cell epitaxy structure  140 , the adhesive layer  150 , the solar cell permanent substrate  160 , and the second electrode  161  along a cutting line  170  to form a solar cell device  200  as shown in  FIG. 1H . 
         [0021]      FIG. 2A  through  FIG. 2D  are schematic diagrams showing the process flow for manufacturing a light-emitting structure  10  and a solar cell structure  20  in accordance with a second embodiment of the present application. As  FIG. 2A  shows, a common growth substrate  210  is provided for the epitaxial growth of epitaxial materials formed thereon. The material of the common growth substrate  210  may be GaAs or Ge. A light-emitting epitaxy structure  220  is grown on the common growth substrate  210  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the light-emitting epitaxy structure  220  comprises a first conductivity type III-V group compound semiconductor layer, an active layer, and a second conductivity type III-V group compound semiconductor layer (not shown) stacked on the common growth substrate  210 . For example, the first conductivity type III-V group compound semiconductor layer is n-type AlGaInP series material, the active layer is AlGaInP series material, and the second conductivity type III-V group compound semiconductor layer is p-type AlGaInP series material. A stripping layer  230  is grown on the light-emitting epitaxy structure  220  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. The material of the stripping layer  230  may be AlAs or AlGaAs. A solar cell epitaxy structure  240  is grown on the stripping layer  230  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the solar cell epitaxy structure  240  may be a multiple junction solar cell epitaxy structure, which is a serial connection of three cells of GaInP/GaAs/Ge. A tunnel junction structure is disposed between two neighboring cells wherein every cell is formed of III-V group compound semiconductor (not shown). As  FIG. 2B  shows, an adhesive layer  250  is formed on the solar cell epitaxy structure  240 , wherein the material of the adhesive layer  250  may be Al, Au, Pt, Zn, Ag, Ni, Ge, In, Sn, Ti, Pb, Cu, Pd, or alloys of the aforementioned metals. In another embodiment, the material of the adhesive layer  250  may be silver glue, spontaneous conductive polymer, polymer materials mixed with conductive materials, or anisotropic conductive film (ACF). A solar cell permanent substrate  260  is provided on the adhesive layer  250 , wherein the material of the solar cell permanent substrate  260  may be germanium (Ge), copper (Cu), aluminum (Al), molybdenum (Mo), tungsten copper (CuW), silicon aluminum (SiAl), gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), silicon (Si), gallium nitride (GaN), aluminum nitride (AlN) or diamond-like carbon (DLC). A wet etching solution containing hydrofluoric acid or citric acid is used for removing the stripping layer  230 , then a light-emitting structure  10  as shown in  FIG. 2C  and a solar cell structure  20  as shown in  FIG. 2D  are formed separately. The light-emitting structure  10  and the solar cell structure  20  are manufactured by the same process in  FIG. 1E  through  FIG. 1H  to form a light-emitting device  100  and a solar cell device  200  respectively (not shown). 
         [0022]      FIG. 3A  through  FIG. 3D  are schematic diagrams showing the process flow for manufacturing a light-emitting structure  10  and a solar cell structure  20  in accordance with a third embodiment of the present application. As  FIG. 3A  shows, a common growth substrate  310  is provided for the epitaxial growth of epitaxial materials formed thereon. The material of the common growth substrate  310  may be GaAs or Ge. A solar cell epitaxy structure  340  is grown on the common growth substrate  310  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the solar cell epitaxy structure  340  may be a multiple junction solar cell epitaxy structure, which is a serial connection of three cells of GaInP/GaAs/Ge. A tunnel junction structure is disposed between two neighboring cells wherein every cell is formed of III-V group compound semiconductor (not shown). A stripping layer  330  is grown on the solar cell epitaxy structure  340  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. The material of the stripping layer  330  may be AlAs or AlGaAs. A light-emitting epitaxy structure  320  is formed on the stripping layer  330  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the light-emitting epitaxy structure  320  comprises a first conductivity type III-V group compound semiconductor layer, an active layer, and a second conductivity type III-V group compound semiconductor layer stacked on the stripping layer  330  (not shown). For example, the first conductivity type III-V group compound semiconductor layer is n-type AlGaInP series material, the active layer is AlGaInP series material, and the second conductivity type III-V group compound semiconductor layer is p-type AlGaInP series material. As  FIG. 3B  shows, an adhesive layer  350  is formed on the light-emitting epitaxy structure  320 , wherein the material of the adhesive layer  350  may be Al, Au, Pt, Zn, Ag, Ni, Ge, In, Sn, Ti, Pb, Cu, Pd, or alloys of the aforementioned metals. In another embodiment, the material of the adhesive layer  350  may be silver glue, spontaneous conductive polymer, polymer materials mixed with conductive materials, or anisotropic conductive film (ACF). A light-emitting device permanent substrate  380  is provided on the adhesive layer  350 , wherein the material of the light-emitting device permanent substrate  380  may be germanium (Ge), copper (Cu), aluminum (Al), molybdenum (Mo), tungsten copper (CuW), silicon aluminum (SiAl), gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), silicon (Si), gallium nitride (GaN), aluminum nitride (AlN) or diamond-like carbon (DLC). A wet etching solution containing hydrofluoric acid or citric acid is used for removing the stripping layer  330 , then solar cell structure  20  as shown in  FIG. 3C  and a light-emitting structure  10  as shown in  FIG. 3D  are formed separately. 
         [0023]      FIG. 3E  through  FIG. 3H  are schematic diagrams showing the process flow for manufacturing a light-emitting device  100  and a solar device  200  in accordance with the above mentioned embodiments of the present application. As  FIG. 3E  shows, a transparent conductive layer  321  is formed on the light-emitting epitaxy structure  320 , and a first electrode  322  is formed on the transparent conductive layer  321 . A second electrode  381  is formed under the light-emitting device permanent substrate  380  opposite to the adhesive layer  350 . Finally, dicing the transparent conductive layer  321 , the light-emitting epitaxy structure  320 , the adhesive layer  350 , the light-emitting device permanent substrate  380 , and the second electrode  381  along a cutting line  370  to form a light-emitting device  100  as shown in  FIG. 3F . As  FIG. 3G  shows, an anti-reflective layer  342  is formed on a portion of the solar cell epitaxy structure  340 , and a first electrode  341  is formed on the remained portion of the solar cell epitaxy structure  340 . A second electrode  312  is formed under the common growth substrate  310  opposite to the solar cell epitaxy structure  340 . Finally, dicing the anti-reflective layer  342 , the solar cell epitaxy structure  340 , the common growth substrate  310 , and the second electrode  312  along a cutting line  370  to form a solar cell device  200  as shown in  FIG. 3H . 
         [0024]      FIG. 4A  through  FIG. 4D  are schematic diagrams showing the process flow for manufacturing a light-emitting structure  10  and a solar cell structure  20  in accordance with a fourth embodiment of the present application. As  FIG. 4A  shows, a common growth substrate  410  is provided for the epitaxial growth of epitaxial materials formed thereon, wherein the common growth substrate  410  having a first surface  410   a  and a second surface  410   b . The material of the common growth substrate  410  may be GaAs or Ge. A stripping layer  430  is grown on the first surface  410   a  of the common growth substrate  410  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. The material of the stripping layer  430  may be AlAs or AlGaAs. A light-emitting epitaxy structure  420  is grown on the stripping layer  430  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the light-emitting epitaxy structure  420  comprises a first conductivity type III-V group compound semiconductor layer, an active layer, and a second conductivity type III-V group compound semiconductor layer (not shown) stacked on the stripping layer  430 . For example, the first conductivity type III-V group compound semiconductor layer is n-type AlGaInP series material, the active layer is AlGaInP series material, and the second conductivity type III-V group compound semiconductor layer is p-type AlGaInP series material. A solar cell epitaxy structure  440  is grown on the second surface  410   b  the common growth substrate  410  by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the solar cell epitaxy structure  440  may be a multiple junction solar cell epitaxy structure, which is a serial connection of three cells of GaInP/GaAs/Ge. A tunnel junction structure is disposed between two neighboring cells wherein every cell is formed of III-V group compound semiconductor (not shown). As  FIG. 4B  shows, an adhesive layer  450  is formed on the light-emitting epitaxy structure  420 , wherein the material of the adhesive layer  450  may be Al, Au, Pt, Zn, Ag, Ni, Ge, In, Sn, Ti, Pb, Cu, Pd, or alloys of the aforementioned metals. In another embodiment, the material of the adhesive layer  450  may be silver glue, spontaneous conductive polymer, polymer materials mixed with conductive materials, or anisotropic conductive film (ACF). A light-emitting device permanent substrate  480  is provided on the adhesive layer  450 , wherein the material of the light-emitting device permanent substrate  480  may be germanium (Ge), copper (Cu), aluminum (Al), molybdenum (Mo), tungsten copper (CuW), silicon aluminum (SiAl), gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), silicon (Si), gallium nitride (GaN), aluminum nitride (AlN) or diamond-like carbon (DLC). A wet etching solution containing hydrofluoric acid or citric acid is used for removing the stripping layer  430 , then a solar cell structure  20  as shown in  FIG. 4C  and a light-emitting structure  10  as shown in  FIG. 4D  are formed separately. 
         [0025]      FIG. 5  shows the growth temperatures for growing a light-emitting epitaxy structure and a solar cell epitaxy structure in accordance with a fifth embodiment of the present application. A common growth substrate Ge is provided for the epitaxial growth of epitaxial materials formed thereon. A solar cell epitaxy structure is grown on the common growth substrate by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the solar cell epitaxy structure may be a multiple junction solar cell epitaxy structure, which is a serial connection of three cells of GaInP/GaAs/Ge (layer 5/layer 3/layer 1). A tunnel junction structure is (layer 2, layer 4) disposed between two neighboring cells wherein every cell is formed of III-V group compound semiconductor. The growth temperature of the these layers is 600° C. A stripping layer (layer 6) is grown on the solar cell epitaxy structure by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. The growth temperature of the stripping layer is 650° C. A light-emitting epitaxy structure is formed on the stripping layer by, for example, metal organic chemical vapor deposition (MOCVD) method, liquid phase deposition (LPD) method, or molecular beam epitaxy (MBE) method. In the embodiment, the light-emitting epitaxy structure comprises a first conductivity type III-V group compound semiconductor layer, an active layer, and a second conductivity type III-V group compound (layer 7-layer 9). The growth temperature of the these layers is 700° C. 
         [0026]      FIG. 6  shows a schematic diagram of a backlight module device  600  in accordance with a sixth embodiment of the present application. The backlight module device  600  comprises a light source device  610  having the light-emitting device  100  in one of the above mentioned embodiments, an optics device  620  deposited on the light extraction pathway of the light source device  610 , and a power supplement  630  which provides a predetermined power to the light source device  610 . 
         [0027]      FIG. 7  shows a schematic diagram of an illumination device  700  in accordance with a seventh embodiment of the present application. The illumination device  700  can be automobile lamps, street lights, flashlights, indicator lights and so forth. The illumination device  700  comprises a light source device  710  having the light-emitting device  100  in one of the above mentioned embodiments, a power supplement  720  which provides a predetermined power to the light source device  710 , and a control element  730  which controls the current driven into the light source device  710 . 
         [0028]      FIG. 8  shows a schematic diagram of a solar cell module  800  in accordance with an eighth embodiment of the present application. The solar cell module  800  comprises a heat sink  860  which provides the heat dissipation, a receiver  850  on the heat sink  860 , a solar cell device  200  in one of the above mentioned embodiments on the receiver  850  wherein the solar cell device electrically connects with the receiver  850  by wire  840 , a secondary optic lens  820  on the solar cell device  200 , and a first optic lens  810  on the secondary optic lens  820  wherein the first optic lens  810  and the secondary optic lens  820  are used for focusing the sunlight. 
         [0029]    In accordance with the embodiments in the application, the first conductivity type III-V group compound semiconductor layer and the second conductivity type III-V group compound semiconductor layer of the light-emitting epitaxy structure are two single-layer structures or two multiple layers structure (“multiple layers” means two or more than two layers) having different electrical properties, polarities, dopants for providing electrons or holes respectively. If the first conductivity type III-V group compound semiconductor layer and the second conductivity type III-V group compound semiconductor layer are composed of the semiconductor materials, the conductivity type can be any two of p-type, n-type, and i-type. The active layer disposed between the first conductivity type III-V group compound semiconductor layer and the second conductivity type III-V group compound semiconductor layer is a region where the light energy and the electrical energy could transfer or could be induced to transfer. 
         [0030]    In another embodiment of this application, the light emission spectrum of the light-emitting device  100  after transferring can be adjusted by changing the physical or chemical arrangement of one layer or more layers in the active layer. The material of the active layer can be AlGaInP or AlGaInN. The structure of the active layer can be a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), or a multi-quantum well (MQW) structure. Besides, the wavelength of the emitted light could also be adjusted by changing the number of the pairs of the quantum well in a MQW structure. 
         [0031]    In one embodiment of this application, a buffer layer (not shown) could be optionally formed between the common growth substrate and the light-emitting epitaxy structure. The buffer layer between two material systems can be used as a buffer system. For the structure of the light-emitting device, the buffer layer is used to reduce the lattice mismatch between two material systems. On the other hand, the buffer layer could also be a single layer, multiple layers, or a structure to combine two materials or two separated structures where the material of the buffer layer can be organic, inorganic, metal, semiconductor, and so on, and the function of the buffer layer can be as a reflection layer, a heat conduction layer, an electrical conduction layer, an ohmic contact layer, an anti-deformation layer, a stress release layer, a stress adjustment layer, a bonding layer, a wavelength converting layer, a mechanical fixing structure, and so on. The material of the buffer layer can be AlN, GaN, or other suitable materials. The fabricating method of the buffer layer can be sputter or atomic layer deposition (ALD). 
         [0032]    A contact layer (not shown) can also be optionally formed on the light-emitting epitaxy structure. The contact layer is disposed on the second conductivity group type III-V compound semiconductor layer opposite to the active layer. Specifically speaking, the contact layer could be an optical layer, an electrical layer, or the combination of the two. An optical layer can change the electromagnetic radiation or the light from or entering the active layer. The term “change” here means to change at least one optical property of the electromagnetic radiation or the light. The above mentioned property includes but is not limited to frequency, wavelength, intensity, flux, efficiency, color temperature, rendering index, light field, and angle of view. An electrical layer can change or be induced to change the value, density, or distribution of at least one of the voltage, resistance, current, or capacitance between any pair of the opposite sides of the contact layer. The composition material of the contact layer includes at least one of oxide, conductive oxide, transparent oxide, oxide with 50% or higher transmittance, metal, relatively transparent metal, metal with 50% or higher transmittance, organic material, inorganic material, fluorescent material, phosphorescent material, ceramic, semiconductor, doped semiconductor, and undoped semiconductor. In certain applications, the material of the contact layer is at least one of indium tin oxide (ITO), cadmium tin oxide (CTO), antimony tin oxide, indium zinc oxide, zinc aluminum oxide, and zinc tin oxide. If the material is relatively transparent metal, the thickness is about 0.005 μm-0.6 μm. 
         [0033]    It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the devices in accordance with the present application without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present application covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents. 
         [0034]    Although the drawings and the illustrations above are corresponding to the specific embodiments individually, the element, the practicing method, the designing principle, and the technical theory can be referred, exchanged, incorporated, collocated, coordinated except they are conflicted, incompatible, or hard to be put into practice together. 
         [0035]    Although the present application has been explained above, it is not the limitation of the range, the sequence in practice, the material in practice, or the method in practice. Any modification or decoration for present application is not detached from the spirit and the range of such.