Patent ID: 7179987

Claim:
A method for producing solar cells from a crystalline silicon semiconductor wafer ( 1 ), said method comprising: diffusing an emitter layer ( 4 ) of a different dopant type than the wafer on the entire surface of a semiconductor wafer ( 1 ); locally applying a doping layer ( 2 ) of the same type of doping as the semiconductor wafer ( 1 ); alloying in the doping layer ( 2 ) to form a doped layer ( 3 ) such that a highly doped back surface field region ( 7 ) and a metallic back contact with eutectic composition ( 9 ) are formed; removing the eutectic composition ( 9 ) to produce electric insulation between p + and n + regions; and applying a back base contact ( 5 ) of smaller dimensions than said back surface field region ( 7 ).