Abstract:
A photoelectrical element having a thermal-electrical structure including: a photoelectrical transforming layer, two semiconductor layers formed on the two opposite sides of the photoelectrical transforming layer respectively, an electrically conductive structure formed on at least one of the semiconductor layer, and a thermal-electrical structure formed in the electrically conductive structure, wherein the thermal-electrical structure performs the thermal-electrical transformation to promote current spreading effect, or proceed electrical-thermal transformation to dissipate the heat from the photoelectrical transforming layer.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a photoelectrical element, and in particular, to a photoelectrical element comprising a thermal-electrical structure. 
       REFERENCE TO RELATED APPLICATION 
       [0002]    This application claims the right of priority based on Taiwan application Serial No. 099118367, filed on Jun. 4, 2010, and the content of which is hereby incorporated by reference. 
       DESCRIPTION OF BACKGROUND ART 
       [0003]    The photoelectrical elements include many types such as the light-emitting diode (LED), the solar cell, and the photo diode. Take the LED as an example, the LED is a kind of the solid state semiconductor device, which at least comprises a p-n junction formed between the p-type and the n-type semiconductor layers. When a bias is applied to the p-n junction, the holes of the p-type semiconductor layer combine with the electrons of the n-type semiconductor layer to emit the light. The region where the light is emitted from is called the light-emitting region. 
         [0004]    Now, the LED generally has the problem, which is the current spreading not well. In the case of the LED with a top p-type semiconductor, a p-type semiconductor is formed on the light emitting layer and an electrode pad is formed on the p-type semiconductor to lead in the current. The mostly used method to improve the current spreading is that: a current spreading layer such as the metal oxides or GaAs is formed on the p-type semiconductor layer, and an electrode pad is formed on the current spreading layer. Further, one or a plurality of extension electrodes is extended from the electrode pad to improve the current spreading. Even the structure described above is used to improve the current spreading for the LED, the problem of the current crowded still exists in the electrode pad or under the extension electrode thereof. 
         [0005]    Otherwise, the LED also has the heat dissipation problem. When the temperature of the light emitting layer is over high, the recombination rate of the electrons and the holes decreases and the luminous efficiency is impacted. The above-described LED further connects with the other elements to form the light-emitting apparatus. The above-described light-emitting apparatus comprises a sub-mount comprising at least one electric circuit; at least one solder formed on the above-described sun-mount, whereby binding the above-described LED to the sub-mount and electrically connecting the substrate of the LED and the electric circuit of the sub-mount; and an electrical connection structure electrically connecting the electrode pad of the LED and the electric circuit of the sub-mount, wherein the above-described sub-mount comprises the lead frame or the large-scaled mounting substrate, so as to design the electric circuit of the light emitting apparatus and raise the heat dissipation. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    The present application relates to a photoelectrical element having a thermal-electrical structure and the characteristics of better current spreading and heat dissipation. The photoelectrical element comprises: a substrate; a photoelectric conversion stacked-layer formed on the substrate, which comprises a first semiconductor layer formed on the substrate, a photoelectric conversion layer formed on the first semiconductor layer and a second semiconductor layer formed on the photoelectric conversion layer; a conductive structure formed between the substrate and the first semiconductor layer, or on the second semiconductor layer; and a thermal-electrical structure formed inside the conductive structure. 
         [0007]    According to an embodiment of the present application, the conductive structure comprises a transparent conductive layer formed on the second semiconductor layer. The thermal-electrical structure is formed inside the transparent conductive layer, or between the transparent conductive layer and the second semiconductor layer, so as to progress the thermal-electrical conversion. 
         [0008]    According to another embodiment of the present application, the conductive structure comprises a transparent conductive layer formed on the second semiconductor layer and a metal pad formed on the transparent conductive layer. The thermal-electrical structure is formed between the transparent conductive layer and the metal pad, or inside the transparent conductive layer corresponding to the metal pad, so as to progress the thermal-electrical conversion. 
         [0009]    According to another embodiment of the present application, the thermal-electrical structure comprises a metal pad formed between the substrate and the first semiconductor layer, wherein the substrate is a conductive substrate. The thermal-electrical structure is formed between the metal layer and the substrate, so as to progress the thermal-electrical conversion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic view illustrating a thermal-electrical photoelectrical element according to the first embodiment of the present application; 
           [0011]      FIG. 2A  is a schematic view illustrating a thermal-electrical photoelectrical element according to the second embodiment of the present application; 
           [0012]      FIG. 2B  is a schematic view illustrating the thermal-electrical effect according to the thermal-electrical photoelectrical element of the second embodiment of the present application; and 
           [0013]      FIG. 2C  is a schematic view illustrating the thermal-electrical effect according to the thermal-electrical photoelectrical element of the second embodiment of the present application. 
       
    
    
       [0014]    Numerals of drawings are explained as follows;
     100 ,  200 : a photoelectrical element;     101 , 201 : a thermal-electrical structure;     201   a : an endothermic side;     201   b : an exothermic side;     102 ,  202 : a substrate;     106 : a conductive structure;     206 : a reflective structure;     107 ,  207 : a first semiconductor layer;     108 ,  208 : a photoelectric conversion layer;     110 ,  210 : a second semiconductor layer;     112 ,  212 : a transparent conductive layer;     114 ; a metal pad;     114   a : an extension part;     203 : a top electrode;     205 : a bottom electrode;     2011 : a p-type thermal-electrical material;     2012 : an n-type thermal-electrical material.   
 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]    As shown in  FIG. 1 , a photoelectrical element  100  illustrated in the first embodiment of the present application comprises: a substrate  102 ; a photoelectric conversion stacked-layer  104  formed on the substrate  102 ; a conductive structure  106  formed on the photoelectric conversion stacked-layer  104 ; and a thermal-electrical structure  101  formed inside the conductive structure  106 . The photoelectric conversion stacked-layer  104  comprises a first semiconductor layer  107  formed on the substrate  102 , a photoelectric conversion layer  108  formed on the first semiconductor layer  107 , and a second semiconductor layer  110  formed on the photoelectric conversion layer  108 , wherein the first semiconductor layer  107  may be the n-type semiconductor layer, the second semiconductor layer  110  may be the p-type semiconductor layer, and the photoelectric conversion layer  108  is used to emit the light. The photoelectrical element  100  of the embodiment is a light emitting element, or a solar cell when the photoelectric conversion layer  108  is used to absorb the light. The conductive structure  106  formed on the second conductive layer  110  comprises one transparent conductive layer  112  formed on the second conductive layer  110 , and a metal pad  114  formed on the transparent conductive layer  112 , which is used to lead-in the electric current. Further, one or more of extension parts  114   a  is extended from the metal pad  114 . 
         [0033]    The thermal-electrical structure  101  comprises a nano-scaled thermal-electrical material. The thickness of the nano-scaled thermal-electrical material may be from 10 nm to 100 nm. The function of the nano-scaled thermal-electrical material is to convert the thermal energy to the electrical energy, or to absorb the surrounding thermal energy when the electric power is switched on. The nano-scaled thermal-electrical material comprises V-VI group compounds such as Bi 2 Te 3 , rare-earth compounds such as CeAl 2 , Y 2 O 3 , silicides, or SiGe, or other compound semiconductor materials. The thermal-electrical structure  101  is formed between the transparent conductive layer  112  and the second semiconductor layer  110 ; and/or inside the transparent conductive layer  112 ; and/or between the transparent conductive layer  112  and the metal pad  114  or the extension parts  114   a  thereof by vapor deposition When the thermal-electrical structure  101  is formed inside the transparent conductive layer, it can be formed under the metal pad  114  and/or the extension parts  114   a  thereof. When the electric current flows into the photoelectrical element  100  from the metal pad  114 , the thermal-electrical structure  101  converts the thermal energy accumulated in the current crowded area to the electrical energy and improves the current spreading. The thermal-electrical structure  101  may be p-type doped or n-type doped semiconductor material in the embodiment. During the operation of the photoelectrical element, the heat is generated. When the thermal-electrical structure  101  is heated, the thermal-electrical effect occurs regardless of n-type or p-type thermal-electrical structure. The difference is that the electric current flows from the thermal-electrical structure  101  to the photoelectric conversion layer  108  when the thermal-electrical structure  101  is the n-type doped semiconductor; the electric current flows from the thermal-electrical structure  101  to the top of the photoelectrical element  100  when the thermal-electrical structure  101  is the p-type doped semiconductor. The better embodiment of the application is the n-type thermal-electrical structure  101 , which generates the electric current flowing to the photoelectric conversion layer  108  during the current spreading. 
         [0034]    The above-described transparent conductive layer  112  comprises metal oxides such as indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), chromium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), zinc oxide (ZnO); compound semiconductors such as AlGaAs, GaP or the alike; thin-film metal layer or thin-film metal alloy layer with good conductivity wherein the structure may be a single layer or the stacked layer. 
         [0035]    The substrate  102  may be the conductive substrate or the insulating substrate. As shown in  FIG. 1 , the photoelectrical element  100  of the embodiment is a horizontal type light emitting element which comprises the insulating substrate. The photoelectric conversion stacked-layer  104  may be epitaxially formed on the substrate  102  by MOCVD, or be attached to the substrate  102  after being formed on other growth substrate first (not shown in the drawings). 
         [0036]    As shown in  FIG. 2A , a photoelectrical element  200  illustrated in the second embodiment of the application comprises: a substrate  202 ; a photoelectric conversion stacked-layer  204  formed on the substrate  202 ; a reflective layer  206  formed between the photoelectric conversion stacked-layer  204  and the substrate  202 ; and a thermal-electrical structure  201  formed between the reflective layer  206  and the substrate  202 . The embodiment is similar to the first embodiment. The substrate  202  of the embodiment is conductive and forms a conductive structure with the reflective layer  206 . The photoelectric conversion stacked-layer  204  comprises a first semiconductor layer  207  formed on the reflective layer  206 , a photoelectric conversion layer  208  formed on the first semiconductor layer  207 , and a second semiconductor layer  210  formed on the photoelectric conversion layer  208 , wherein the first semiconductor layer  207  may be the p-type semiconductor layer, and the second semiconductor layer  210  may be the n-type semiconductor layer. A transparent conductive layer  212  is formed between the reflective layer  206  and the first semiconductor layer  207  to improve the current spreading. The thermal-electrical structure  201  comprises the nano-scaled materials and is formed between the substrate  202  and the reflective layer  206  or inside the conductive structure. The thermal-electrical material of the thermal-electrical structure  201  comprises V-VI group compounds such as Bi 2 Te 3 , rare-earth compounds such as CeAl 2 , Y 2 O 3 , silicides, or SiGe, or other compound semiconductor materials. Otherwise, a bottom electrode  205  is formed under the substrate  202 , and a top electrode  203  is formed on the photoelectric conversion stacked-layer  204 . 
         [0037]    The two sides of the reflective layer  206  respectively connect to the photoelectric conversion stacked-layer  204  and the substrate  202 . In the embodiment, the photoelectric conversion stacked-layer  204  is formed on another growth substrate which is removed later. Then, the photoelectric conversion stacked-layer  204  is attached to the reflective layer  206 , which is attached to the substrate  202  in advance. The reflective layer  206  comprises the high reflectivity materials such as copper (Cu), aluminum (Al), indium (In), tin (Sn), gold (Au), platinum (Pt), zinc (Zn), silver (Ag), titanium (Ti), lead (Pb), palladium (Pd), germanium (Ge), nickel (Ni), chromium (Cr), cadmium (Cd), cobalt (Co), manganese (Mn), antimony (Sb), bismuth (Bi), gallium (Ga), thallium (TI), arsenic (As), selenium (Se), tellurium (Te), polonium (Po), iridium (Ir), rhenium (Re), rhodium (Rh), osmium (Os), tungsten (W), lithium (Li), sodium (Na), potassium (K), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zirconium (Zr), molybdenum (Mo), lanthanum (La), copper-tin (Cu—Sn), copper-zinc (Cu—Zn), copper-cadmium (Cu—Cd), tin-lead-antimony (Sn—Pb—Sb), tin-lead-zinc (Sn—Pb—Zn), nickel-tin (Ni—Sn), nickel-cobalt (Ni—Co) or Au alloy to reflect the light emitted from the photoelectric conversion layer  208 . 
         [0038]    As shown in  FIG. 2B , the thermal-electrical structure  201  may be the p-type or the n-type semiconductor. In the case of the n-type thermal-electrical structure  201 , the electrons move to the opposite direction of the electric current when the electric current flows through the n-type thermal-electrical structure  201 . Thus, the thermal-electrical structure  201  forms an endothermic side  201   a  and an exothermic side  201   b  so as to drive the thermal energy of the photoelectric conversion layer  208  toward the thermal-electrical structure  201  and facilitate the thermal dissipation. The thermal-electrical structure  201  of the embodiment is n-type so as to operate in coordination to the direction of the electric current. However, the first semiconductor layer  207  of the photoelectric conversion stacked-layer  204  also may be the n-type semiconductor layer and the second semiconductor layer  210  may be the p-type semiconductor layer, wherein the thermal-electrical structure  201  is p-type so as to operate in coordination to the direction of the electric current. 
         [0039]    Otherwise, the thermal-electrical structure  201  may be p-type and n-type simultaneously. As shown in  FIG. 2C , a plurality of the p-type thermal-electrical materials  2011  and the n-type thermal-electrical materials  2012  are formed in turn between the substrate  202  and the reflective layer  206 . 
         [0040]    The principle and the efficiency of the present application illustrated by the embodiments above are not the limitation of the application. Any person having ordinary skill in the art can modify or change the aforementioned embodiments. 
         [0041]    Therefore, the protection range of the rights in the application will be listed as the following claims.