Photovoltaic device

Claim 2

A photovoltaic device comprising: a semiconductor film made mainly of amorphous silicon, said semiconductor film including a plurality of semiconductor layers which comprise at least one semiconductor-to-semiconductor junction, a transparent front electrode on one side of said semiconductor film, and a back electrode on the other side of said semiconductor film; wherein one end layer of said semiconductor layers which neighbors on said back electrode includes, at least one first type sub-layer of an alloyed amorphous silicon which contains not only hydrogen and a dopant for one conductivity type but also at least one element selected from the group of nitrogen and oxygen so as to provide a conversion efficiency which is improved in resistance to thermal degradation, and at least one second type sub-layer of an amorphous silicon which contains hydrogen and a dopant for said one conductivity type, but which is substantially free of said at least one element selected from the group consisting of nitrogen and oxygen.

Claim 3

A photovoltaic device in accordance with claim 1, wherein a plurality of said first type and second type sub-layers are stacked alternately.

Claim 4

A photovoltaic device in accordance with claim 1, wherein said semiconductor-to-semiconductor junction is a p-i-n junction.

Claim 5

A photovoltaic device in accordance with claim 3, wherein said photovoltaic device is of a tandem type and said semiconductor film contains a plurality of p-i-n junctions.

Claim 6

A photovoltaic device in accordance with claim 1, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen in the concentration range of less than 50 at.%.

Claim 7

A photovoltaic device in accordance with claim 5, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen more preferably in the oncentration range of 3 at.% to 30 at.%.

Claim 8

A photovoltaic device in accordance with claim 6, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen most preferably in the concentration range of 10 at.% to 25 at.%.

Claim 9

A photovoltaic device in accordance with claim 1, wherein said back electrode comprises a layer of one selected from the group consisting of Al and Ag.

Claim 10

A photovoltaic device in accordance with claim 1, wherein said back electrode comprises stacked layers of one selected from the group consisting of Ag/Ti, TCO/Ag, and TCO/Ag/Ti.

Claim 11

A photovoltaic device comprising; a semiconductor film made mainly of amorphous silicon, said semiconductor film including a plurality of semiconductor layers which comprise at least one semiconductor-to-semiconductor junction, a transparent front electrode on one side of said semiconductor film, and a back electrode on the other side of said semiconductor film; wherein one end layer of said semiconductor layers which neighbors on said back electrode includes, at least one first type sub-layer of an alloyed amorphous silicon which contains not only hydrogen and a dopant for one conductivity type but also at least one element selected from the group of nitrogen and oxygen so as to provide a conversion efficiency which is improved in resistance to thermal degradation, and at least one second type sub-layer of an amorphous silicon which contains hydrogen and a dopant for said one conductivity type, with said back electrode being contiguous to said second type sub-layer, but which is substantially free of said at least one element selected from the group consisting of nitrogen and oxygen.

Claim 12

A photovoltaic device comprising; a semiconductor film made mainly of amorphous silicon, said semiconductor film including a plurality of semiconductor layers which comprise at least one semiconductor-to-semiconductor junction, a transparent front electrode on one side of said semiconductor film, and a back electrode on the other side of said semiconductor film; wherein one end layer of said semiconductor layers which neighbors on said back electrode includes, at least one first type sub-layer of an alloyed amorphous silicon which contains not only hydrogen and a dopant for one conductivity type but also at least one element selected from the group of nitrogen and oxygen so as to provide a conversion efficiency which is improved in resistance to thermal degradation, and at least one second type sub-layer of an amorphous silicon which contains hydrogen and a dopant for said one conductivity type, with said back electrode being contiguous to said second type sub-layer, but which is substantially free of said at least one element selected from the group consisting of nitrogen and oxygen.

Claim 13

A photovoltaic device in accordance with claim 10, wherein a plurality of said first type and second type sub-layers are stacked alternately.

Claim 14

A photovoltaic device in accordance with claim 10, wherein said semiconductor-to-semiconductor junction is a p-i-n junction.

Claim 15

A photovoltaic device in accordance with claim 12, wherein said photovoltaic device is of a tandem type and said semiconductor film contains a plurality of p-i-n junctions.

Claim 16

A photovoltaic device in accordance with claim 10, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen in the concentration range of less than 50 at.%.

Claim 17

A photovoltaic device in accordance with claim 14, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen more preferably in the concentration range of 3 at.% to 30 at.%.

Claim 18

A photovoltaic device in accordance with claim 15, wherein said first type sub-layer contains at least one selected from the group consisting of nitrogen and oxygen most preferably in the concentration range of 10 at.%. to 25 at.%.

Claim 19

A photovoltaic device in accordance with claim 10, wherein said back electrode comprises a layer of one selected from the group consisting of Al and Ag.

Claim 20

A photovoltaic device in accordance with claim 10, wherein said back electrode comprises stacked layers of one selected from the group consisting of Ag/Ti, TCO/Ag, and TCO/Ag/Ti.