Abstract:
A light-emitting structure includes a transparent substrate; a first transparent conductive layer formed on the transparent substrate and having a first top surface and a second top surface substantially coplanar with the first top surface; a first light-emitting stack formed on the first top surface; and a first electrode directly formed on the second top surface.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 13/730,130, entitled “LIGHT EMITTING DIODE HAVING A TRANSPARENT SUBSTRATE”, filed Dec. 28, 2012, which is a divisional application of U.S. patent application Ser. No. 13/114,384, entitled “LIGHT EMITTING DIODE HAVING A TRANSPARENT SUBSTRATE”, filed May 24, 2011, which is a continuation application of U.S. patent application Ser. No. 11/724,310, entitled “LIGHT EMITTING DIODE HAVING A TRANSPARENT SUBSTRATE”, filed Mar. 15, 2007 claiming the right of priority based on Taiwan application Ser. No. 090115871, filed Jun. 27, 2001; the content of which is incorporated herein by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a light-emitting device, more specifically to a light-emitting device with a light-emitting stack on a transparent conductive layer. 
       DESCRIPTION OF BACKGROUND ART 
       [0003]    Light emitting diodes (LEDs) are employed in a wide variety of applications including optical display devices, traffic lights, data storage equipment, communication devices, illumination apparatuses, and medical treatment equipment. Some of the main goals of engineers who design LEDs are to increase the brightness of the light emitted from LEDs and to reduce the cost of manufacturing LEDs. 
         [0004]    U.S. Pat. No. 5,783,477 discloses a method of bonding two compound semiconductor surfaces to produce an ohmic contact interface. The method of manufacturing a prior art LED is to create an ohmic contact interface by aligning the crystallographic orientation and rotational alignment of two semiconductor surfaces and applying uniaxial pressure to the semiconductor wafers at a temperature of 1000° C. In actual procedure, however, it is difficult and expensive to align the crystallographic orientation and rotational alignment of the two semiconductor surfaces. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    A light-emitting structure includes a transparent substrate; a first transparent conductive layer formed on the transparent substrate and having a first top surface and a second top surface substantially coplanar with the first top surface; a first light-emitting stack formed on the first top surface; and a first electrode directly formed on the second top surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a cross sectional view of a high brightness light emitting diode having a transparent substrate according to the first embodiment of the present invention. 
           [0007]      FIG. 2  is a cross sectional view showing a first semiconductor multilayer before wafer bonding during the manufacturing method according to the present invention. 
           [0008]      FIG. 3  is a cross sectional view showing an amorphous interface layer and a second semiconductor multilayer before wafer bonding during the manufacturing method according the present invention. 
           [0009]      FIG. 4  is a cross sectional view showing a third semiconductor multilayer after wafer bonding, but before removal of the non-transparent substrate during the manufacturing method according the present invention. 
           [0010]      FIG. 5  is a cross sectional view showing a third semiconductor multilayer after removal of the non-transparent substrate and formation of an ITO transparent conductive layer during the manufacturing method according the present invention. 
           [0011]      FIG. 6  is a cross sectional view of a high brightness light emitting diode having a transparent substrate according to the second embodiment of the invention. 
           [0012]      FIG. 7  is a cross sectional view of a high brightness light emitting diode having a transparent substrate according to the third embodiment of the invention. 
           [0013]      FIG. 8  is a cross sectional view of a high brightness light emitting diode having a transparent substrate according to the fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]      FIG. 1  is a cross sectional view of a high brightness light emitting diode (LED)  1  having a transparent substrate according to the first embodiment of the present invention. In the LED  1 , an indium tin oxide (ITO) amorphous interface layer  11  is formed on a sapphire transparent substrate  10 . A top surface of the ITO amorphous interface layer  11  comprises a first surface region and a second surface region. The LED further comprises layers stacked upon each other on the first surface region in the following order, bottom to top: a contact layer of p+-type GaAs  12 , a cladding layer of a p-type AlGaInP  13 , a multiple quantum well (MQW) light-emitting layer  14 , a cladding layer of n-type AlGaInP  15 , a stop layer of n-type AlGaAs  16 , and an ITO transparent conductive layer  18 . A first electrode  19  is located on the ITO transparent conductive layer  18 , and a second electrode  20  is located on the second surface region. 
         [0015]      FIG. 2  and  FIG. 3  illustrate a method for manufacturing the light emitting diode  1  according to the first embodiment of the present invention. A first semiconductor multilayer  2  is created by first forming an n-type stop layer  16  of AlGaAs on an n-type GaAs semiconductor substrate  17 . Then an n-type cladding layer  15  of AlGaInP is formed on the n-type stop layer  16 . An MQW light-emitting layer  14  of AlGaInP is formed on the n-type cladding layer  15 . A p-type cladding layer  13  of AlGaInP is formed on the MQW light-emitting layer  14 , and a p+-type contact layer  12  of GaAs is formed on the p-type cladding layer  13 . Next, a second semiconductor multilayer  3  is created. The second semiconductor multilayer  3  comprises an amorphous interface layer  11  of ITO formed on a sapphire substrate  10 . As is shown in  FIG. 4 , a third semiconductor multilayer  4  is produced by inverting the first semiconductor multilayer  2 , placing it on the semiconductor multilayer  3 , and bonding the first semiconductor multilayer  2  to the second semiconductor multilayer  3  by elevating temperature and applying uniaxial pressure to the semiconductor multilayers.  FIG. 4  and  FIG. 5  show the next step, which comprises the removal of the n-type GaAs semiconductor substrate  17  from the multilayer  4  and the formation of a first ITO transparent conductive layer  18  on the n-type stop layer  16 , producing a fourth semiconductor multilayer  5 . Next, an interface exposed region is formed by etching away a portion of the fourth semiconductor multilayer  5  from the first ITO transparent conductive layer  18  to the ITO amorphous interface layer  11 . Finally, a first contact electrode  19  and a second contact electrode  20  are formed on the first ITO transparent conductive layer  18  and the interface exposed region, respectively. 
         [0016]      FIG. 6  illustrates a light emitting diode  6  having a transparent substrate according to a second preferred embodiment of the present invention. A transparent substrate  611  of p-type GaP is formed on an ohmic contact electrode  610 . A first p+-type contact layer  612  of GaAs is formed on the transparent substrate  611 . An indium tin oxide (ITO) amorphous interface layer  613  is formed on the first p+-type contact layer  612 . A second p+-type contact layer  614  of GaAs is formed on the ITO amorphous interface layer  613 . A p-type cladding layer  615  of AlGaInP is formed on the second p+-type contact layer  614 . A multiple quantum well (MQW) light-emitting layer  616  of AlGaInP is formed on the p-type cladding layer  615 . An n-type cladding layer  617  of AlGaInP is formed on the MQW light-emitting layer  616 . An n-type stop layer  618  of AlGaAs is formed on the n-type cladding layer  617 . An ITO transparent conductive layer  619  is formed on the n-type stop layer  618 . An electrode  620  is formed on the ITO transparent conductive layer  619 . 
         [0017]      FIG. 7  illustrates a light emitting diode  7  having a transparent substrate according to a third preferred embodiment of the present invention. A transparent substrate  711  of n-type GaP is formed on a first electrode  710 . An indium tin oxide (ITO) amorphous interface layer  713  is formed on the transparent substrate  711 . An n-type contact layer  714  of GaP is formed on the ITO amorphous interface layer  713 . An n-type cladding layer  715  of AlGaInP is formed on the n-type contact layer  714 . A multiple quantum well (MQW) light-emitting layer  716  of AlGaInP is formed on the n-type cladding layer  715 . A p-type cladding layer  717  of AlGaInP is formed on the MQW light-emitting layer  716 . A p-type buffer layer  718  of AlGaAs is formed on the p-type cladding layer  717 . A p+-type contact layer  719  of GaAs is formed on the p-type buffer layer. An ITO transparent conductive layer  720  is formed on the p+-type contact layer  719 . A second electrode  721  is formed on the ITO transparent conductive layer  720 . 
         [0018]      FIG. 8  illustrates a light emitting diode  8  having a transparent substrate according to a fourth preferred embodiment of the present invention. An indium tin oxide (ITO) amorphous interface layer  811  is formed on a transparent substrate  810  of glass. A top surface of the ITO amorphous interface layer  811  comprises a first surface region and a second surface region. An n+-type reverse tunneling contact layer  814  of InGaN is formed on the first surface region. A p-type cladding layer  815  of GaN is formed on the n+-type reverse tunneling contact layer  814 . A multiple quantum well (MQW) light-emitting layer  816  of InGaN is formed on the p-type cladding layer  815 . An n-type cladding layer  817  of GaN is formed on the MQW light-emitting layer  816 . A first Ti-Al contact electrode is formed on the n-type cladding layer  817 . A second electrode  820  is formed on the second surface region. 
         [0019]    According to the description of these embodiments, LEDs having a transparent substrate can be manufactured by a method of bonding two chips using an amorphous interface layer. LEDs made according to the present invention are easier to manufacture, less expensive to manufacture, and brighter than those made according to the prior art. 
         [0020]    While the invention has been disclosed and described with reference to these preferred embodiments, the scope of the invention is not limited to these preferred embodiments. Any variation and modifications of the invention still falls within the spirit and scope of the invention. For example, using a transparent conductive layer of adhesive agent instead of a single-crystal interface layer or using a single quantum well light-emitting layer instead of a multiple quantum well light-emitting layer cannot escape the scope and spirit of the invention. Moreover, the manufacturing method of the present invention is also suitable for manufacturing a light emitting diode having a non-transparent substrate. 
         [0021]    Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. 
         [0022]    Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.