Abstract:
A light-emitting device comprises: a light-emitting stack having an upper side, a first edge having an end point, and a second edge opposite to the first edge; a first bonding region arranged on the upper side, near the first edge, and far from the end point; a second bonding region separated from to the first bonding region by a first distance and being far from the end point; a third bonding region arranged on the upper side; a fourth bonding region separated from the third bonding region by a second distance longer than the first distance; a first electrode connected to the first bonding region; a second electrode connected to the second bonding region; a third electrode connected to the third bonding region; a fourth electrode connected to the fourth bonding region; and a fifth electrode connected to the first bonding region and pointing to the fourth bonding region.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 13/459,342, entitled “Light-emitting device”, filed on Apr.30, 2012, which is a continuation application of U.S. patent application Ser. No. 12/292,593, entitled “Light-emitting device”, filed on Nov. 21, 2008, and the content of which is hereby incorporated by references. 
     
    
     BACKGROUND OF THE DISCLOSURE 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a light-emitting device, and in particular to a semiconductor light-emitting device. 
         [0004]    2. Description of the Related Art 
         [0005]    The light-emitting mechanism and the structure of a light-emitting diode (LED) are different from that of the conventional light sources. The LED has advantages of small size and high reliability, and has been widely used in different fields such as displays, laser diodes, traffic lights, data storage apparatus, communication apparatus, lighting apparatus, and medical apparatus. 
         [0006]    Referring to  FIG. 1A and 1B .  FIG. 1A  is the schematic top view of a conventional nitride-based light-emitting device  1 , and  FIG. 1B  illustrates a cross-sectional view of the conventional nitride-based light-emitting device  1  along the A-A′ line in the  FIG. 1A . The conventional nitride-based light-emitting device  1  includes a substrate  11 , an n-type nitride-based layer  12 , a light-emitting layer  13 , a p-type nitride-based layer  14 , a p-type transparent electrode  15 , an n-type electrode  16  having the function as a bonding pad, and a p-type bonding pad  17 . The p-type bonding pad  17  is used for current injection. The current is injected through the p-type bonding pad  17  and moves to and spread through the p-type transparent electrode  15 . Electrons and holes recombine in the light-emitting layer  13  and then produce photons. In fact, as shown in  FIG. 1B , the current is crowded in the area where the p-type transparent electrode  15  is close to the n-type electrode  16  to cause a poor light-emitting efficiency. Besides, the temperature in the current crowded area is so high that the life of conventional nitride-based light-emitting device  1  is reduced. 
         [0007]    In order to resolve above problems, a known art disclosed a light-emitting device  2  which is illustrated by a top view as shown in  FIG. 2 . Another known art also disclosed a light-emitting device  3  which is illustrated by a top view as shown in  FIG. 3 . Referring to  FIG. 2 , the light-emitting device  2  includes a p-type electrode and an n-type electrode. The p-type electrode includes a p-type bonding pad  24 , two first armed electrodes  24   a  extending from the p-type bonding pad  24 , and second armed electrodes  24   b  interposed between two first armed electrodes  24   a . The armed electrode can be used to decrease the light absorption of the p-type electrode. The current is injected from the p-type bonding pad  24  and spread by the armed electrodes. The n-type electrode includes an n-type bonding pad  25 , third armed electrodes  25   a , and fourth armed electrodes  25   b . The current is injected from the p-type electrode, moves to the light-emitting region of the light-emitting device  2 , and then flows to and out of the n-type electrode. The p-type armed electrodes  24   a ,  24   b  and the n-type armed electrodes  25   a ,  25   b  are interdigitated between each other. 
         [0008]    Referring to the  FIG. 3 , the light-emitting device  3  includes an n-type electrode having a first contact  35  and an n-type fingered electrode  36  connected with the first contact  35  at a first side of the light-emitting device  3 , a p-type electrode having a second contact  37  and two fingered electrodes  38   a ,  38   b  connected with the second contact  37  at a second side of the light-emitting device  3 , wherein the first side and the second side are opposite to each other. The n-type fingered electrode  36  is extended from the first side to the second side, the p-type fingered electrodes  38   a ,  38   b  are extended from the second side to the first side, and the n-type fingered electrode  36  and the p-type fingered electrodes  38   a ,  38   b  are interdigitated between each other. The light-emitting devices  2  and  3  can resolve the current crowding and low light efficiency problems of the conventional light-emitting device  1  by the interdigitated extending electrodes. 
         [0009]    Referring to  FIG. 4 , further another known art disclosed a light-emitting device  4 . The epitaxial structure of the light-emitting device  4  includes a spiral-shaped trench, a p-type metal electrode  41  located in the exposed surface of the trench, an n-type metal electrode  42  located on the un-trenched surface of the epitaxial structure, a p-type bonding pad  43 , and an n-type bonding pad  44 , wherein the p-type metal electrode  41  and the n-type metal electrode  42  are parallel and distributed in spiral shape, which can resolve the current crowding and low light efficiency problems of the conventional light-emitting device  1   
         [0010]    In above conventional light-emitting devices, the designs of electrodes adopt transparent electrodes or decrease the electrode area such as armed, fingered and spiral-shaped electrodes to optimize the light extraction area. In general, the width of an electrode is designed to be smaller than that of a bonding pad to avoid increasing the light absorption area of the electrode. 
       SUMMARY OF THE DISCLOSURE 
       [0011]    A light-emitting device comprises: a light-emitting stack having an upper side, a first edge having an end point, and a second edge opposite to the first edge; a first bonding region arranged on the upper side, near the first edge, and far from the end point; a second bonding region separated from to the first bonding region by a first distance and being far from the end point; a third bonding region arranged on the upper side; a fourth bonding region separated from the third bonding region by a second distance longer than the first distance; a first electrode connected to the first bonding region; a second electrode connected to the second bonding region; a third electrode connected to the third bonding region; and a fourth electrode connected to the fourth bonding region; and a fifth electrode connected to the first bonding region and pointing to the fourth bonding region. 
         [0012]    A light-emitting device comprises: a light-emitting stack having an upper side, a first edge having an end point, and a second edge opposite to the first edge; a first bonding region arranged on the upper side, near the first edge, and far from the end point; a second bonding region separated from to the first bonding region by a first distance and being far from the end point; a third bonding region arranged on the upper side; a fourth bonding region separated from the third bonding region by a second distance longer than the first distance; a first electrode connected to the first bonding region; a second electrode connected to the second bonding region; a third electrode connected to the third bonding region; a fourth electrode connected to the fourth bonding region; a fifth electrode connected to the first bonding region; and a sixth electrode connected to the second bonding region and separated from the fifth electrode. 
         [0013]    A light-emitting device comprises: a light-emitting stack having an upper side, a first edge and a second edge; a first bonding region arranged on the upper side and near the first edge; a second bonding region arranged on the upper side and near the first edge; a third bonding region arranged on the upper side and distanced from the first edge; a fourth bonding region arranged on the upper side and distanced from the first edge; a first electrode connected to the first bonding region; a second electrode connected to the second bonding region; a third electrode connected to the third bonding region; a fourth electrode connected to the fourth bonding region; a fifth electrode connected to the first bonding region; and a sixth electrode connected to the second bonding region and separated from the fifth electrode; wherein the fifth electrode and the sixth electrode are between the third bonding region and the fourth bonding region. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings are included to provide easy understanding of the invention, and are incorporated herein and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to illustrate the principles of the invention. 
           [0015]      FIGS. 1A-1B  are a schematic top view and a cross-sectional view of a conventional light-emitting device  1 . 
           [0016]      FIG. 2  is a schematic cross-sectional view of a conventional light-emitting device  2 . 
           [0017]      FIG. 3  is a schematic cross-sectional view of a conventional light-emitting device  3 . 
           [0018]      FIG. 4  is a schematic cross-sectional view of a conventional light-emitting device  4 . 
           [0019]      FIGS. 5A-5C  are a schematic top view and cross-sectional views of a light-emitting device in accordance with a first embodiment of the present invention. 
           [0020]      FIGS. 6A-6B  are a schematic top view and a cross-sectional view of a light-emitting device in accordance with a second embodiment of the present invention. 
           [0021]      FIG. 7  is a schematic cross-sectional view of a light-emitting device in accordance with a third embodiment of the present invention. 
           [0022]      FIGS. 8A-8B  are a schematic top view and a cross-sectional view of a light-emitting device in accordance with a fourth embodiment of the present invention. 
           [0023]      FIG. 9  is a schematic cross-sectional view of a light source element including a light-emitting device of the present invention. 
           [0024]      FIG. 10  is a schematic cross-sectional view of a backlight module including a light-emitting device of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
         [0026]    Referring to  FIG. 5A , the schematic top view shows a light-emitting device  10  in accordance with a first embodiment of the present invention.  FIG. 5B  illustrates a cross-sectional view of the light-emitting device  10  along the B-B′ line in the  FIG. 5A . The light-emitting device  10  such as an LED includes a substrate  100 , a buffer layer  110 , a first semiconductor layer  120 , a light-emitting layer  130 , a second semiconductor layer  140 , a first electrode  151 , a second electrode  152 , a first and second pad  161  and  162 . In the embodiment, the shape of light-emitting device  10  is a rectangular cube. Each side of the light-emitting device  10  is about 610 μm in length. The area of the top surface is 3.72×10 5  μm 2 , and the area of the light-emitting layer  130  is accorded with the area of the top surface. The buffer layer  110 , first semiconductor layer  120 , light-emitting layer  130 , and second semiconductor layer  140  are formed on the substrate  100  by the method of metal organic chemical vapor deposition (MOCVD) or molecular-beam epitaxy (MBE). 
         [0027]    After forming the epitaxial structure, an etching step is performed. A trench  170  is formed in the epitaxial structure by etching the epitaxial structure. A part of the first semiconductor layer  120  is exposed through the trench  170 . The trench  170  is formed in a rectangular spiral shape, and the un-etched epitaxial structure is also formed in a rectangular spiral shape. 
         [0028]    Next, the first electrode  151  and the first pad  161  are formed on the exposed surface of the first semiconductor layer  120 . The shape of first electrode  151  is the same as the rectangular spiral shape of the trench  170 , and the width of the first electrode  151  is about 22 μm. The position of first pad  161  can be between two end points of the first electrode  151  or in a non-end portion of the first electrode  151 . In this embodiment, the first pad  161  is disposed at the non-end portion of the first electrode  151 . Because the light-emitting device  10  has a larger light-emitting area, a larger operating current is necessary for a higher emitting efficiency. In order to achieve the larger amount of injected current, more pads area for current injecting are necessary. In this embodiment, the area of the first pad  161  is designed to be capable of containing at least two wires for current injecting, and the light-emitting device has enough wires for current injecting to improve the light-emitting efficiency. The first pad  161  has an area between 1.5×10 4  μm 2  to 6.2×10 4  μm 2 . The area of the first pad  161  is 1.9×10 4  μm 2  in the embodiment. 
         [0029]    Further, the second electrode  152  and the second pad  162  are formed and connected with each other on the remained epitaxial structure. The width of the second electrode  152  is about 20 μm, and the shape of it is a rectangular spiral. The second pad  162  can be situated between two end points of the second electrode  152  or on a non-end portion of the second electrode  152 . In this embodiment, the second pad  162  is situated on the non-end portion of the second electrode  152 . Similarly, in order to achieve a larger injected current, in this embodiment, the area of the second pad  162  is designed to be capable of containing at least two wires for current injecting. thus the light-emitting device has enough amounts of wires for current injecting to improve the light-emitting efficiency. The second pad  162  has an area between 1.5×10 4  μm 2  to 6.2×10 4  μm 2 . The area of the second pad  162  is 1.73×10 4  μm 2  in the embodiment. 
         [0030]    The shapes of the first pad  161  and the second pad  162  include rectangular shape, circular shape, or any other shapes. The first pad  161  and the second pad  162  including bonding regions are disposed on the first and the second electrodes respectively. In the embodiment, both shapes of the first pad  161  and the second pad  162  are two overlapped circles. Bonding regions  161 A and  161 B of the first pad  161 , and bonding regions  162 A and  162 B of the second pad  162  can provide a better identification and avoid duplicate bonding of two wires on the same pad. There are wires connecting to the bonding regions  161 A,  161 B,  162 A, and  162 B respectively so the light-emitting device receives enough current by wires to have sufficient electrons and holes to recombine and then emits light. Referring to  FIG. 5C , the schematic cross-sectional view shows a pad  161  with Au bonding bulges  180 A and  180 B formed on the bonding regions  161 A and  161 B respectively. During the bonding process, Au bulges are melted by raising temperature, and then the wires  171 A and  171 B are bonded with Au bonding bulges  180 A and  180 B respectively. Similarly, other two wires are bonded at the bonding regions  162 A and  162 B by the same method. 
         [0031]    The direction of the spiral shape is clockwise or counterclockwise, and the numbers of spiral are not limited. The material of the substrate  100  includes but is not limited to sapphire. The material of the buffer layer  110  includes but is not limited to AlN, AlGaN, or GaN. The material of the first semiconductor layer  120  includes but is not limited to (Al x Ga 1-x ) y In 1-y N wherein 0≦x≦1 and 0≦y≦1. The light-emitting layer  130  includes but is not limited to a double heterostructure or a multi-quantum well including materials such as (Al p Ga 1-p ) q In 1-q N wherein 0≦p≦1 and 0≦q≦1. The material of the second semiconductor layer  140  includes but is not limited to (Al a Ga 1-a ) b In 1-b N wherein 0≦a≦1 and 0≦b≦1. 
         [0032]    The material of the first electrode  151  is selected from materials which can be formed an ohmic contact with the first semiconductor layer  120 , such as a single layer, multiple layers or alloy selected from Ti, Al, and Au, or other metal-oxide conductive material. The first pad  161  includes but is not limited to a single layer, multiple layer or alloy selected from Ti, Al, and Au. The material of the second electrode  152  is selected from materials which can be formed an ohmic contact with the second semiconductor layer  140 , such as a single layer, multiple layers or alloy selected from Ni and Au, or other metal-oxide conductive material. The second pad  162  includes but is not limited to a single layer, multiple layer or alloy selected from Ni and Au. 
         [0033]    The areas of the first pad  161  and the second pad  162  do not need to satisfy the condition of having the area capable of accommodating at least two wires for current injecting at the same time. It can be one of the first pad  161  and the second pad  162  satisfying the condition that the area of pad is capable of containing at least two wires. 
         [0034]    Referring to  FIG. 6A , the schematic top view shows a light-emitting device  20  in accordance with a second embodiment of the present invention.  FIG. 6B  illustrates a cross-sectional view of the light-emitting device  20  along the C-C′ line in the  FIG. 6A . The light-emitting device  20  includes a substrate  200 , an adhesive layer  210 , a current conductive layer  280 , a first semiconductor layer  220 , a light-emitting layer  230 , a second semiconductor layer  240 , a first electrode  251 , a second electrode  252 , a first and second pad  261  and  262 . In the embodiment, the shape of the light-emitting device  20  is a rectangular cube, and the length of each side is about 787 μm. The area of the top surface is 6.19×10 5  μm 2 , and the area of the light-emitting layer  230  is in accord with the area of the top surface. The epitaxial structure of the light-emitting device  20  is formed on a growth substrate (not illustrated). After the epitaxial structure is grown, a current conductive layer  280  with a high current conductivity is formed on the first semiconductor layer  220 , which can spread the current injected from the electrode. Next, the epitaxial structure and the substrate  200  are adhered together by the adhesive layer  210 . 
         [0035]    After the adhering step, a trench  270  is formed in the epitaxial structure by etching the epitaxial structure. A part of the current conductive layer  280  is exposed through the trench  270 . The trench  270  is formed in a fingered shape; the finger is extended from the first side to the opposite second side of the light-emitting device  20 . The un-etched epitaxial structure also forms a fingered shape. 
         [0036]    Next, the first electrode  251  and the first pad  261  are formed on the exposed surface of the current conductive layer  280 . The shape of the first electrode  251  is the same as the fingered shape of the trench  270 , and the first electrode  251  includes at least three linearly extending electrodes and a laterally extending electrode connected the three linearly extending electrodes. The first electrode  251  has a width smaller than or equal to 25 μm. In this embodiment, the width of the first electrode  251  is about 23 μm. The first pad  261  can be situated between two end points of the first electrode  251  or on a non-end portion of the first electrode  251 . In this embodiment, the first pad  261  is situated on the non-end portion of the first electrode  251 . Similarly, in order to achieve a higher emitting efficiency, in this embodiment, the area of the first pad  261  is designed to be capable of containing at least two wires for current injecting so the light-emitting device  20  has enough wires for current injection. The area of the first pad  261  is 2.15×10 4  μm 2  in the embodiment. 
         [0037]    Further, the second electrode  252  and the second pad  262  are formed and connected with each other on the remained epitaxial structure. The second electrode  252  includes three linearly extending electrodes extended from the second side to the opposite first side of the light-emitting device  20 , and interdigitated between the three linearly extending electrode of the first electrode  251 , and a laterally extending electrode connecting the three linearly extending electrodes. The second electrode  252  has a width smaller than or equal to 25 μm. In this embodiment, the width of the second electrode  252  is about 20 μm. The second pad  262  is disposed at the second side and connected with the second electrode  252 . The area of the second pad  262  is 1.27×10 4  μm 2  in the embodiment. 
         [0038]    In this embodiment, the shape of the second pad  262  is rectangular, and the second pad  262  is situated on the non-end portion of the second electrode  152 . The first pad  261  is capable of containing two bonding regions  261 A and  261 B. Each of regions  261 A and  261 B electrically connects to at least a wire for bonding, such that a better identification can be achieved for the next bonding procedure to avoid different wires being bonded at the same bonding region. The second pad  262  has a circular shape, and only one bonding region  262 A which connects to a wire electrically. The area of the second pad  262  is also can be designed as an size containing at least two wires, such as the area of the second pad  262  is 1.5×10 4  μm 2 . 
         [0039]    The material of the growth substrate includes but is not limited to sapphire, SIC, GaN, GaAs, or GaP. The material of the substrate  200  includes but is not limited to SiC, GaN, GaP, Si, AlN, ZnO, MgO, MgAl 2 O 4 , GaAs, glass, sapphire, metal, or compound materials. The adhesive layer  210  includes a conductive adhesive layer or an insulating adhesive layer. The material of the conductive adhesive layer includes but is not limited to Ag, Au, Al, In, or Sn, or alloy of them, spontaneous conductive polymer, or polymer doped with metal like Al, Au, Pt, Zn, Ag, Ni, Ge, In, Sn, Ti, Pb, Cu, Pd, or other metals. The material of the insulating adhesive layer includes but is not limited to spin on glass (SOG), silicone, benzocyclobutene (BCB), epoxy, polyimide (PI), or perfluorocyclobutane (PFCB). When the adhesive layer  210  is the insulating adhesive layer, the material of the substrate  200  is not limited. In the embodiment, the material of the substrate  200  is Si. The material of Si has a higher heat transfer coefficient to transfer the heat produced by the light-emitting device to the environment. A reflective layer  211  is further disposed on one side of the adhesive layer  210 . The material of the reflective layer  211  includes but is not limited to metal, oxide, or the combination thereof. The oxide material for the reflective layer  211  includes but is not limited to AlO x , SiO x , or SiN x . 
         [0040]    When the adhesive layer  210  is the conductive adhesive layer, the material of the substrate  200  includes but is not limited to glass, sapphire, or AlN. It also can disposes an insulating layer between the current conductive layer  280  and the adhesive layer  210 , or the adhesive layer  210  and the substrate  200 , wherein the material of the substrate  200  is not limited. Referring to  FIG. 7 , a cross-sectional view shows a light-emitting device in accordance with a third embodiment of the present invention.  FIG. 7  illustrates an insulating layer  690  disposed between the adhesive layer  210  and the current conductive layer  280  for isolation. The material of the insulating layer includes but is not limited to SiN x  or SiO 2 . The material of the first semiconductor layer  220  includes but is not limited to (Al m Ga 1-m ) r In 1-r N wherein 0≦m≦1 and 0≦r≦1 or (Al c Ga 1-c ) d In 1-d P wherein 0≦c≦1 and 0≦d≦1. The light-emitting layer  230  includes but is not limited to a double heterostructure or a multi-quantum well including materials such as (Al e Ga 1-e ) f In 1-f N wherein 0≦e≦1 and 0≦f≦1 or (Al i Ga 1-i ) j In 1-j P wherein 0≦i≦1 and 0≦j≦1. The material of the second semiconductor layer  240  includes but is not limited to (Al k Ga 1-k ) h In 1-h N wherein 0≦k≦1 and 0≦h≦1 or (Al s Ga 1-s ) t In 1-t P wherein and 0≦s≦1 and 0≦t≦1. 
         [0041]    The material of the first electrode  251  includes but is not limited to a single metal layer, multiple metal layers or alloy of Ni, and Au, or other conductive metal oxide layer. The material of first pad  261  includes but is not limited to a single metal layer, multiple metal layers or alloy of Ni, and Au. The material of the second electrode  252  includes but is not limited to a single metal layer, multiple metal layers or alloy of Ti, Al, and Au, or conductive metal oxide layer. The second pad  262  includes but is not limited to a single metal layer, multiple metal layers or alloy of Ti, Al, and Au. The shapes of the first electrode  251  and the second electrode  252  include M linearly extending electrodes respectively, wherein M≧1. The first electrode  251  can include M linearly extending electrodes, wherein M≧1, and the second electrode  252  includes M−1 linearly extending electrodes. 
         [0042]    Referring to  FIG. 8A , the schematic top view shows a light-emitting device  30  in accordance with a fourth embodiment of the present invention.  FIG. 8B  illustrates a cross-sectional view of the light-emitting device  30  along the D-D′ line in the  FIG. 8A . The structure of the light-emitting device  30  is similar to that of the light-emitting device  10  including a substrate  100 , a buffer layer  110 , a first semiconductor layer  120 , a light-emitting layer  130 , and a second semiconductor layer  140 . After forming the epitaxial structure, a current conductive layer  380  is disposed on the second semiconductor layer  140 . In the embodiment, the light-emitting device  300  is a rectangular cube and the length of each side of the light-emitting device  30  is about 1143 μm. The area of the top surface is 1.31×10 6  μm 2 , and the area of the light-emitting layer  130  is in accord with the area of the top surface. 
         [0043]    After the step of forming the current conductive layer  380 , an etching step is performed. A trench  370  is formed in the current conductive layer  380  and the epitaxial structure by etching part of them. A part of the first semiconductor layer  120  is exposed through the trench  370 . The shape of the trench  370  is formed in a pair of spiral, and the un-etched current conductive layer  380  and epitaxial structure are also formed in a pair of spiral shape. 
         [0044]    Referring to  FIG. 8A , the light-emitting device  30  includes a pair of first electrodes  351 A and  351 B and a pair of second electrodes  361 A and  361 B formed in a pair of spiral shape respectively. After the trench  370  is formed, the first electrodes  351 A and  351 B, and first pads  361 A and  361 B are formed on the exposed surface of the first semiconductor layer  120 . The shape of first electrodes  351 A and  351 B are the same as the pair of spiral shape of the trench  370 . The width of the first electrodes  351 A or  351 B is about 10 μm respectively. First pads  361 A and  361 B can be situated between two end points of first electrodes  351 A and  351 B or on a non-end portion of first electrodes  351 A and  351 B. In this embodiment, first pads  361 A and  361 B are situated on the non-end portions of first electrodes  351 A and  351 B near a first side of the light-emitting device  30  and a second side opposite to the first side. The area of first pad  361 A and  361 B are the same as 19×10 4  μm 2 . 
         [0045]    Further, the second electrodes  352 A and  352 B, and the second pad  362  are formed on the remained current conductive layer  380 . The width of the second electrode  352 A or  352 B is about 10 μm respectively. The second electrodes  352 A and  352 B are formed in a spiral shape and connected with the second pads  362  respectively. The second pad  362  can be disposed at a third side neighboring with the first side and the second side, and connect to second electrodes  352 A and  352 B. In this embodiment, the area of the second pad  362  is designed to be capable of containing at least two wires for current injection so the light-emitting device  30  has enough current to higher brightness. The area of the second pad  362  is 1.9×10 4  μm 2  in the embodiment. 
         [0046]    In the embodiment, the shape of the second pad  362  formed as two circles partially overlapped includes two bonding region  362 A and  362 B such that a better identification can be achieved for the next bonding procedure to avoid two wires being bonded on the same bonding region. There are wires connecting to the bonding regions  361 A,  361 B,  362 A, and  362 B respectively, so the light-emitting device  30  receives enough current by wires to have sufficient electrons and holes to recombine and then emits light. The shape of the light-emitting device  30  includes but is not limited to a square shape or a rectangular shape. The material of the current conductive layers  280  and  380  includes but is not limited to indium tin oxide, cadmium tin oxide, zinc oxide, or zinc tin oxide. Each surface of the light-emitting device can be a rough surface by an epitaxial or an etching process, such as a rough surface around the substrate or around the epitaxial structure, a rough surface in the top light extraction surface, or a rough surface under and contact with the electrode, to improve the light extraction efficiency. 
         [0047]    Referring to  FIG. 9 , the schematic cross-sectional view shows a light source apparatus  90  in accordance with a fifth embodiment of the present invention. The light source apparatus  90  includes a light-emitting device of above embodiments. The light source apparatus  7  is a lighting apparatus such as streetlamps, vehicle lamps, or indoor lightings. It also can be traffic lights or backlights of a module in a planar display. The light source apparatus  90  includes a light source  910  with the light-emitting device of above embodiments, a power supply system  920 , and a control element  930  for controlling the power supply system  920 . 
         [0048]    Referring to  FIG. 10 , the schematic cross-sectional view shows a backlight module  100  in accordance with an eighth embodiment of the present invention. The backlight module  100  includes the light source apparatus  90  and an optical element  1010 . The optical element  1010  is used to operate the light emitted from the light source apparatus  90  to satisfy the requirements of the backlight. The optical element  1010  includes a photonic lattice, a color filter, a wavelength conversion layer, an antireflective layer  211 , a lens or the combination thereof. 
         [0049]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of this, it is intended that the present invention covers modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.