Photovoltaic device with double-junction

Abstract

A photovoltaic device includes a substrate having a first doped-type, a first doped region having a second doped-type in the substrate, a second doped region in a portion of the first doped region and exposing the other portion of the first doped region, and a third doped region in the exposed portion of the first doped region. The polarity of the second doped-type is substantially reversed with that of the first doped-type. The second doped region has a polarity substantially identical to that of the first doped-type and a doped concentration substantially greater than that of the substrate. The third doped region has a polarity substantially identical to that of the second doped-type and a doped concentration substantially greater than that of the first doped region. The first doped-type is one of N-type and P-type, while the second doped-type is the other of P-type and N-type.

What is claimed is: 
     
         1 . A photovoltaic device, comprising:
 a substrate having a first surface and an opposite, second surface, wherein the substrate has a first doped-type;   a first doped region in the first surface of the substrate, wherein the first doped region has a second doped-type, and a polarity of the second doped-type is substantially reversed with a polarity of the first doped-type;   a second doped region in a portion of the first doped region and exposing the other portion of the first doped region, wherein a polarity of the second doped region is substantially identical to the polarity of the first doped-type;   a third doped region in the exposed portion of the first doped region, wherein a polarity of the third doped region is substantially identical to the polarity of the second doped-type and a doped concentration of the third doped region is substantially greater than a doped concentration of the first doped region;   a fourth doped region in the second surface of the substrate, wherein a polarity of the fourth doped region is substantially identical to the polarity of the first doped-type, and a doped concentration of the fourth doped region is substantially greater than the doped concentration of the second doped region;   a first electrode on the third doped region; and   a second electrode on the fourth doped region.   
     
     
         2 . The photovoltaic device of  claim 1 , further comprising:
 a first dielectric layer covering on the first surface of the substrate, wherein the first dielectric layer has a first opening exposing the first electrode.   
     
     
         3 . The photovoltaic device of  claim 1 , wherein a doped concentration of the second doped region is substantially greater than the doped concentration of the substrate. 
     
     
         4 . The photovoltaic device of  claim 1 , further comprising:
 a second dielectric layer covering on the second surface of the substrate.   
     
     
         5 . The photovoltaic device of  claim 1 , wherein the first doped-type is one of N-type and P-type, and the second doped-type is the other of P-type and N-type. 
     
     
         6 . The photovoltaic device of  claim 1 , wherein the first doped region has a depth ranging from about 1 micron to about 3 microns. 
     
     
         7 . The photovoltaic device of  claim 1 , wherein the second doped region has a depth ranging from about 0.05 microns to about 0.5 microns. 
     
     
         8 . The photovoltaic device of  claim 1 , wherein a boundary of the second doped region is contacted with a material of the first doped region and a material of the substrate.