Abstract:
An LED includes a base and an LED die grown on the base. The LED die includes two spaced electrodes and two exposed semiconductor layers. The two electrodes are respectively formed on top surfaces of the two semiconductor layers. At least one of the electrodes extends downwardly from the top surface of the corresponding semiconductor layer along a lateral edge of the LED die to electrically connect an exterior electrode via transparent conducting resin.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to semiconductor devices and, more particularly, to a light emitting diode (LED). 
         [0003]    2. Description of Related Art 
         [0004]    In recent years, LEDs have been widely used in devices to provide illumination. Typically, an LED may include an LED die, an electrode layer, and two gold wires. The LED die may include a light emitting surface. Two spaced terminals may be formed on the light emitting surface. The LED die may be electrically connected to the electrode layer through wire bonding, in which the two gold wires may be respectively soldered to the terminals and the electrode layer. However, part of the light emitting surface of the LED die may be blocked by the solder joint and the gold wires, resulting in a decreased illumination efficiency of the LED. 
         [0005]    Accordingly, it is desirable to provide an LED which can overcome the described limitations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a top view of an LED according to a first embodiment of the present disclosure. 
           [0007]      FIG. 2  is a cross sectional view of the LED of  FIG. 1 , taken along II-II line thereof. 
           [0008]      FIG. 3  is similar to the  FIG. 2 , further with the LED electrically connecting to exterior electrodes. 
           [0009]      FIG. 4  is a top view of an LED according to a second embodiment of the present disclosure. 
           [0010]      FIG. 5  is a cross sectional view of the LED of  FIG. 4 , taken along V-V line thereof. 
           [0011]      FIG. 6  is similar to the  FIG. 5 , further with the LED electrically connecting exterior electrodes. 
           [0012]      FIG. 7  is a cross sectional view of an LED according to a third embodiment of the present disclosure, wherein the LED electrically connects exterior electrodes. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Embodiments of an LED will now be described in detail below and with reference to the drawings. 
         [0014]    Referring to  FIGS. 1-2 , an LED  100  according to a first embodiment is shown. The LED  100  includes a base  10 , an LED die  20  grown on the base  10 , an N-type electrode  30  and a P-type electrode  40  formed on the LED die  20 . 
         [0015]    The base  11  is made of sapphire, SiC, Si, GaAs, LiAlO 2 , MgO, ZnO, GaN, AlO, or InN. 
         [0016]    The LED die  20  includes a buffer layer  21  formed on a top surface of the base  10 , an N-doped region  22  formed on a top surface of the buffer layer  21 , an active layer  23  formed on a top surface the N-doped region  22 , a P-doped region  24  formed on a top surface of the active layer  23 , and an electrically conductive layer  25  formed on a top surface of the P-doped region  24 . The buffer layer  21  has a size equal to that of the base  10  and covers the whole of the top surface of the base  10 . The N-doped region  22  has a size equal to that of the buffer layer  21  and covers the whole of the top surface of the buffer layer  21 . The active layer  23  covers a left side portion of the top surface of the N-doped region  22  to expose a right side portion of the top surface of the N-doped region  22 . The P-doped region  24  covers the whole of the top surface of the active layer  23 . The electrically conductive layer  25  covers the whole of the top surface of the P-doped region  24 . 
         [0017]    The buffer layer  21  is used to decrease crystal lattices dislocation of the N-doped region  22  and improve a quality of the N-doped region  22 . In this embodiment, the buffer layer  21  is made of GaN, AlGaN, AN, or InGaN. The active layer  23  includes a single quantum well structure, a multiple quantum well structure, and/or quantum dot structure. The electrically conductive layer  25  is formed by evaporating or sputtering and made of Ni/Au, Indium Tin Oxide, Indium Zinc Oxide, Indium Tungsten Oxide, or Indium Gallium Oxide. The electrically conductive layer  25  is transparent. The right side of the top surface of the N-doped region  22  is exposed by etching. 
         [0018]    The N-type electrode  30  is a metallic pad, and formed on the right side of the top surface of the N-doped region  22  by evaporating or sputtering. 
         [0019]    The P-type electrode  40  is an L-shaped strip and extends from a left side portion of a top surface of the electrically conductive layer  25 , and extends down along lateral edges of the LED die  20  and the base  10 . In this embodiment, a bottom end of the P-type electrode  40  is coplanar with a bottom surface of the base  10 . Alternatively, the P-type electrode  40  extends to the bottom surface of the base  10 . The P-type electrode  40  is formed by evaporating or sputtering. An electrically insulating layer  50  is formed on the lateral edges of the LED die  20  and the base  10  to isolate the lateral edge of the LED die  20  from the P-type electrode  40 . Thus, the LED die  20  insulates from the P-type electrode  40  except the electrically conductive layer  25 . 
         [0020]    Referring to  FIG. 3 , when the LED  100  electrically connects an exterior power source, the bottom end of the P-type electrode  40  and the bottom surface of the base  10  are adhered to a first exterior electrode  60  via transparent conducting resin  80 , and the N-type electrode  30  electrically connects a second exterior electrode  70  via opposite ends of a gold wire  90  respectively soldered on the N-type electrode  30  and the second exterior electrode  70 . 
         [0021]    In this embodiment, the P-type electrode  40  is an L-shaped strip and directly adhered to the first exterior electrode  60  by the transparent conducting resin  80 , so the solder and the gold wire are not need to connect the P-type electrode  40  and the first exterior electrode  60 . The P-type electrode  40  may be narrower relative to the conventional LED. Thus, a light emitting surface of the LED  100  blocked by the solder is decreased relative to the conventional LED, and an illumination efficiency of the LED  100  is improved. 
         [0022]    Referring to  FIGS. 4-5 , an LED  200  of a second embodiment is shown. The LED  200  is similar to the LED  100  of the first embodiment, and a difference therebetween is that a P-type electrode  40   a  of the LED  200  is a circular pad and formed on the top surface of the electrically conductive layer  25 , and an N-type electrode  30   a  is an L-shaped strip, the N-type electrode  30   a  extends from outward the right side of the N-doped region  22 , and extends down along lateral edges of the N-doped region  22 , the buffer layer  21 , and the base  10 . A bottom end of the N-type electrode  30   a  is coplanar to the bottom surface of the base  10 . 
         [0023]    Referring to  FIG. 6 , when the LED  200  electrically connects an exterior power source, the bottom end of the N-type electrode  30   a  and the bottom surface of the base  10  are adhered to a second exterior electrode  70   a  by the transparent conducting resin  80 , and the P-type electrode  40   a  electrically connects a first exterior electrode  60   a  through wire boding by a gold wire  90   a.    
         [0024]    Referring to  FIG. 7 , an LED  300  of a third embodiment is shown. The LED  300  is similar to the LED  100  of the first embodiment, and a difference therebetween is that an N-type electrode  30   b  of the LED  300  is an L-shaped strip. The N-type electrode  30   b  extends from outward the right side of the N-doped region  22 , and extends down along lateral edges of the N-doped region  22 , the buffer layer  21 , and the base  10 . A bottom end of the N-type electrode  30   b  is coplanar to the bottom surface of the base  10 . The bottom ends of the P-type electrode  40  and the N-type electrode  30   b  are respectively adhered to a first exterior electrode  60   b  and a second exterior electrode  70   b.  The first exterior electrode  60   b  and the second exterior electrode  70   b  are attached to the bottom surface of the base  10  and are spaced from each other. 
         [0025]    It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.