Patent ID: 7030413

Claim:
A photovoltaic device comprising: a crystalline semiconductor substrate of a first conductivity type, wherein said substrate is a principal power generating layer of said photovoltaic device; a non-intrinsic amorphous semiconductor film of said first conductivity type or of a second conductivity type opposite said first conductivity type; and an intrinsic amorphous semiconductor film having a thickness of 20 to 250 Å and being interposed directly between said substrate and said non-intrinsic amorphous semiconductor film; wherein said intrinsic amorphous semiconductor film has a varied optical band gap with a first optical band gap value on a first side of said intrinsic amorphous semiconductor film contacting said substrate and a second optical band gap value greater than said first optical band gap value on a second side of said intrinsic amorphous semiconductor film contacting said non-intrinsic amorphous semiconductor film; wherein said intrinsic amorphous semiconductor film comprises at least a first intrinsic amorphous semiconductor layer being an amorphous silicon layer along said first side having said first optical band gap value and a second intrinsic amorphous semiconductor layer along said second side having said second optical band gap value; and wherein said second intrinsic amorphous semiconductor layer is a layer selected from the group consisting of an amorphous silicon carbide layer, an amorphous silicon oxide layer, and an amorphous silicon nitride layer.