Abstract:
A solar cell is fabricated. Its light-absorbing part is close to a heat-diffusing device. Thus, the solar cell has low electrical and thermal Impedance. The solar cell has a strong structure, high efficiency and is fit for mass production.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a solar cell device; more particularly, relates to adhering a light absorption region to a heat dissipation device for reducing an electric resistance and a thermal resistance with strong structure and high efficiency. 
       DESCRIPTION OF THE RELATED ARTS 
       [0002]    A general solar cell device, as shown in  FIG. 5 , comprises a thin substrate  4  and a plurality of electric contact pads  5  deposed above the substrate  4 , where the solar cell device can be adhered to a heat dissipation device  7  by using a bonding agent on a lower flat surface of the substrate  4 . 
         [0003]    However, the above structure requires a complex procedure. For example, since the substrate  4  is weak during wire bonding on wafer, an extra substrate is needed for bonding; but the same extra substrate is removed later. As a result, the fabricating time is prolonged and is not good for mass production. In addition, the whole structure does not have enough heat dissipation efficiency. Hence, when the device is used under a high condensing light, heat is greatly aggregated and so the device is reduced in efficiency and even in life of use. Hence, the prior art does not fulfill all users&#39; requests on actual use. 
       SUMMARY OF THE INVENTION 
       [0004]    The main purpose of the present invention is to adhere a light absorption region of a solar cell to a heat dissipation device for reducing an electric resistance and a thermal resistance with strong structure and high efficiency. 
         [0005]    To achieve the above purpose, the present invention is a solar cell device having low electrical and thermal impedance, comprising a substrate, a plurality of electric contact pads and an ohmic contact, where the substrate has an upper surface and a lower surface; the lower surface is corresponding to the upper surface; the substrate has a recessed hole on the lower surface; the recessed hole has openings connected with four recessed channels; the recessed hole comprises a central recess and a recess sidewall; the recess sidewall surrounds the central recess; the electric contact pads is deposed on the upper surface of the substrate; and the ohmic contact is deposed on the lower surface, the recessed hole and the recessed channels. Accordingly, a novel solar cell device having low electrical and thermal impedance is obtained. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0006]    The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawings, in which 
           [0007]      FIG. 1  is the sectional side view showing the preferred embodiment according to the present invention; 
           [0008]      FIG. 2  to  FIG. 4  are the first to the third sectional bottom-up views showing the preferred embodiment; and 
           [0009]      FIG. 5  is the view of the prior art. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]    The following description of the preferred embodiment is provided to understand the features and the structures of the present invention. 
         [0011]    Please refer to  FIG. 1 , which is a sectional side view showing a preferred embodiment according to the present invention. As shown in the figure, the preferred embodiment is a solar cell device having low electrical and thermal impedance, comprising a substrate  1 , a plurality of electric contact pads  2  and an ohmic contact  3 . 
         [0012]    The substrate  1  has an upper surface  11  and a lower surface  12 ; the lower surface  12  is corresponding to the upper surface  11 ; the lower surface  12  has a columnar recessed hole  13  and four recessed channels  14 ˜ 17  connected with openings of the recessed hole  13 ; the recessed channel  13  is made of an electric and thermal conductive material; the recessed hole  13  comprises a central recess  131  and a recess sidewall  132  surrounding the central recess  131 ; and, every one of the recessed channels  14 ˜ 17  has a depth not deeper than that of the recessed hole  13 . 
         [0013]    The electric contact pads  2  are deposed on at least a part of the upper surface  11 . 
         [0014]    The ohmic contact  3  is deposed on the lower surface  12 , the recessed hole  13  and the recessed channels  14 ˜ 17 . Thus, a novel solar cell device having low electrical and thermal impedance is obtained. 
         [0015]    Please refer to  FIG. 2  to  FIG. 4 , which are a first to a third sectional bottom-up views showing the preferred embodiment. As shown in the figures, on using the present invention, a recessed hole  13  is a square hole (in  FIG. 2 ) or a circular hole (in  FIG. 3 ); and recessed channels  14 ˜ 17  connected with openings of the recessed hole  13  are two channels ( 14 , 15  or  16 , 17 ) or three channels  14 ˜ 16  (in  FIG. 4 ). 
         [0016]    A light absorption region of the present invention is thus adhered to a heat dissipation device. Hence, an electric resistance and a thermal resistance are greatly reduced when the light absorption region is bonded to the recessed channels. Furthermore, the present invention has a strong structure and do not need extra bonding substrate while photon is reflected at back of the device; so more current is outputted efficiently and the present invention can be easily fabricated for mass production. 
         [0017]    To sum up, the present invention is a solar cell device having low electrical and thermal impedance, where a light absorption region of the solar cell device is adhered to a heat dissipation device for reducing an electric resistance and a thermal resistance with a strong structure and a high efficiency; and the present invention can be easily fabricated for mass production. 
         [0018]    The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.