Photoelectric conversion device and method of making the same

Abstract

A photoelectric conversion device has a non-single-crystal semiconductor laminate member formed on a substrate having a conductive surface, and a conductive layer formed on the non-single-crystal semiconductor laminate member. The non-single-crystal semiconductor laminate member has such a structure that a first non-single-crystal semiconductor layer having a P or N first conductivity type, an I-type second non-single-crystal semiconductor layer and a third non-single-crystal semiconductor layer having a second conductivity type opposite the first conductivity type are laminated in this order. The first (or third) non-single-crystal semiconductor layer is disposed on the side on which light is incident, and is P-type. The I-type non-single-crystal semiconductor layer has introduced thereinto a P-type impurity, such as boron which is distributed so that its concentration decreases towards the third (or first) non-single-crystal semiconductor layer in the thickwise direction of the I-type layer.

1. A method for manufacturing a photoelectric conversion device comprising the steps of:
 forming a first impurity, non-single crystalline semiconductor layer of a first conductivity type on a substrate in a reaction chamber;    depositing a substantially intrinsic semiconductor layer on said first impurity layer by introducing process gas into said reaction chamber together with a dopant gas comprising boron, the introducing ratio of said dopant gas to said process gas being monotonically decreased throughout the deposition of the intrinsic semiconductor layer in order that the impurity concentration in said intrinsic semiconductor layer is monotonically decreased from the interface between said first impurity and intrinsic semiconductor layers;    forming a second impurity, non-single crystalline semiconductor layer of a second conductivity type opposite to said first conductivity type, the impurity semiconductor layer adjacent to the heavier doping side of said intrinsic layer having the same conductivity type as that corresponding to the dopant gas for said intrinsic semiconductor layer;    forming an electrode arrangement for said conversion device; and    reducing the oxygen concentration in said substantially intrinsic layer to a level less than 5×10 19  atoms/cm 3 .    
     
     
       2. A manufacturing method according to claim  1   5 , wherein the process gas is a hydride or halide of silicon and the dopant gas is a hydride or halide of boron. 
     
     
       3. A manufacturing method according to claim  2   5 , wherein the concentration of the dopant gas relative to the concentration of the process gas is continuously decreased with time within a range of less than 5 ppm. 
     
     
       4. A method as in claim  3  where  5 , wherein said level is as low as 5×10 18  atoms/cm 3 . 
     
     
       5. A manufacturing method as in  claim 1  where for manufacturing a photoelectric conversion device comprising the steps of:
   forming a first impurity, non - single crystalline semiconductor layer of a first conductivity type on a substrate in a reaction chamber;    
   depositing a substantially intrinsic semiconductor layer on said first impurity layer by introducing process gas into said reaction chamber together with a dopant gas comprising boron, the introducing ratio of said dopant gas to said process gas being monotonically decreased throughout the deposition of the intrinsic semiconductor layer in order that the impurity concentration in said intrinsic semiconductor layer is monotonically decreased from the interface between said first impurity and intrinsic semiconductor layers;    
   forming a second impurity, non - single crystalline semiconductor layer of a second conductivity type opposite to said first conductivity type, the impurity semiconductor layer adjacent to the heavier doping side of said intrinsic layer having the same conductivity type as that corresponding to the dopant gas for said intrinsic semiconductor layer;    
   forming an electrode arrangement for said conversion device; and    
   reducing the oxygen concentration in said substantially intrinsic layer to a level less than  5 × 10     19    atoms/cm   3 ,  
   wherein  the reduction of the oxygen concentration is effected by passing said process gas through a molecular sieve or zeolite which adsorbs oxygen.  
 
     
     
       6. A method of claim  1   5 , wherein said semiconductor layer is made of amorphous semiconductor. 
     
     
       7. A method of claim  6   5 , wherein said process gas is filtered in advance of introduction into said reaction chamber. 
     
     
       8. A method for manufacturing a photoelectric conversion device comprising the steps of:
 forming a first impurity, non-single crystalline semiconductor layer of a first conductivity type on a substrate in a reaction chamber;    depositing a substantially intrinsic semiconductor layer on said first impurity layer by introducing process gas into said reaction chamber together with a dopant gas comprising boron, the introducing ratio of said dopant gas to said process gas being monotonically decreased throughout the deposition of the intrinsic semiconductor layer in order that the impurity concentration in said intrinsic semiconductor layer is monotonically decreased from the interface between said first impurity and intrinsic semiconductor layers;    forming a second impurity, non-single crystalline semiconductor layer of a second conductivity type opposite to said first conductivity type, the impurity semiconductor layer adjacent to the heavier doping side of said intrinsic layer having the same conductivity type as that corresponding to the dopant gas for said intrinsic semiconductor layer;    forming an electrode arrangement for said conversion device; and    reducing the carbon concentration in said substantially intrinsic layer to a level less than 4×10 19  atoms/cm 3 .    
     
     
       9. A method as in claim  8  where  10 , wherein said level is as low as 4×10 15  atoms/cm 3 . 
     
     
       10. A manufacturing method as in  claim 8  method for manufacturing a photoelectric conversion device comprising the steps of:
   forming a first impurity, non - single crystalline semiconductor layer of a first conductivity type on a substrate in a reaction chamber;    
   depositing a substantially intrinsic semiconductor layer on said first impurity layer by introducing process gas into said reaction chamber together with a dopant gas comprising boron, the introducing ratio of said dopant gas to said process gas being monotonically decreased throughout the deposition of the intrinsic semiconductor layer in order that the impurity concentration in said intrinsic semiconductor layer is monotonically decreased from the interface between said first impurity and intrinsic semiconductor layers;    
   forming a second impurity, non - single crystalline semiconductor layer of a second conductivity type opposite to said first conductivity type, the impurity semiconductor layer adjacent to the heavier doping side of said intrinsic layer having the same conductivity type as that corresponding to the dopant gas for said intrinsic semiconductor layer;    
   forming an electrode arrangement for said conversion device; and    
   reducing the carbon concentration in said substantially intrinsic layer to a level less than  4 × 10     18    atoms/cm   3   ;   
 wherein the reduction of the carbon concentration is effected by passing said process gas through a molecular sieve or zeolite which adsorbs carbon.  
 
     
     
       11. A method for manufacturing a photoelectric conversion device comprising the steps of:
 forming a first impurity, non-single crystalline semiconductor layer of a first conductivity type on a substrate in a reaction chamber;    depositing a substantially intrinsic semiconductor layer on said first impurity layer by introducing process gas into said reaction chamber together with a dopant gas comprising boron, the introducing ratio of said dopant gas to said process gas being monotonically decreased throughout the deposition of the intrinsic semiconductor layer in order that the impurity concentration in said intrinsic semiconductor layer is monotonically decreased from the interface between said first impurity and intrinsic semiconductor layers;    forming a second impurity, non-single crystalline semiconductor layer of a second conductivity type opposite to said first conductivity type, the impurity semiconductor layer adjacent to the heavier doping side of said intrinsic layer having the same conductivity type as that corresponding to the dopant gas for said intrinsic semiconductor layer;    forming an electrode arrangement for said conversion device; and    reducing the phosphorus concentration in said substantially intrinsic layer to a level less than 5×10 15  atoms/cm 3 .    
     
     
       12. A method as in  claim 11  where said level is as low as 5×10 15  atoms/cm 3 . 
     
     
       13. A manufacturing method as in  claim 11  where the reduction of the phosphorus concentration is effected by passing said process gas through a molecular sieve or zeolite which adsorbs phosphorus. 
     
     
       14. A method as in claims  1 ,  8 , or  11  where  5  or  10 , wherein said first conductivity type is n-type and said second conductivity type is p-type. 
     
     
       15. A method as in claims  1 ,  8 , or  11  where  5  or  10 , wherein said first conductivity type is p-type and said second conductivity type is n-type. 
     
     
       16. A method as in claims  1 ,  8 , or  11  where  5  or  10 , wherein the ratio of said impurity concentration at the interface between said second impurity and intrinsic semiconductor layers to that at said interface between said first impurity and the intrinsic semiconductor layers is 1/10 to 1/100. 
     
     
       17. A method as in  claim 16  where wherein said ratio is 1/20 to 1/40. 
     
     
       18. A method as in claims  1 ,  8 , or  11  where  5  or  10 , wherein said impurity is boron and the boron concentration at said interface between the p-type and intrinsic layers is 2×10 15  to 2×10 17  atoms/cm 3 . 
     
     
       19. A method as in claims  1 ,  8 , or  11  where  5  or  10 , wherein said first layer comprises p-type, non-single crystalline Si x C 1-x  (0<x<1) and said impurity comprises boron.