Multijunction photovoltaic device and fabrication method

Claim 2

A multijunction photovoltaic device, comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, and consisting of first and second sublayers doped with a dopant of the first conductivity type, said first sublayer consisting of an amorphous hydrogenated silicon compound and said second sublayer consisting of a microcrystalline hydrogenated silicon compound, said first sublayer forming an ohmic contact with said bottom layer and said second sublayer forming a tunnel junction with said top layer.

Claim 3

The multijunction device of claim 1 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 4

The multijunction device of claim 1, wherein each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 5

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, and consisting of a first layer comprising a microcrystalline hydrogenated silicon compound and a second layer comprising an amorphous hydrogenated silicon compound, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers.

Claim 6

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, and consisting of a first layer comprising a microcrystalline hydrogenated silicon compound and a second layer comprising an amorphous hydrogenated silicon compound, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers.

Claim 7

The multijunction device of claim 4 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 8

The multijunction device of claim 4 wherein each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 9

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer comprising an amorphous hydrogenated silicon compound and a second layer comprising a microcrystalline hydrogenated silicon compound, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers.

Claim 10

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer comprising an amorphous hydrogenated silicon compound and a second layer comprising a microcrystalline hydrogenated silicon compound, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers.

Claim 11

The multijunction device of claim 7 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 12

The multijunction device of claim 7 wherein each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 13

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 14

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 15

The multijunction device of claim 10 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 16

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein said first and second layers each comprise an amorphous hydrogenated silicon compound; each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 17

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein said first and second layers each comprise an amorphous hydrogenated silicon compound; each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 18

The multijunction device of claim 12 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 19

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein said first and second layers each comprise a microcrystalline hydrogenated silicon compound; each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 20

A multijunction photovoltaic device comprising: a first photovoltaic cell including a plurality of first cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a bottom layer having a first bandgap, said bottom layer being doped with a dopant of a first conductivity type; a second photovoltaic cell including a plurality of second cell layers of hydrogenated amorphous silicon of respectively different conductivity types, said layers being arranged in a stacked configuration and including a top layer having a second bandgap, said top layer being doped with a dopant of a second conductivity type opposite the first conductivity type; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said bottom layer of said first cell and said top layer of said second cell, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with a dopant of the first conductivity type and forming an ohmic contact with said bottom layer, said second layer being doped with a dopant of the second conductivity type and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, wherein said first and second layers each comprise a microcrystalline hydrogenated silicon compound; each of said top and bottom layers further includes an element selected from the group consisting of carbon, nitrogen, oxygen, and fluorine; and said first and second layers of said interface layer being substantially free of carbon, nitrogen, oxygen, and fluorine.

Claim 21

The multijunction device of claim 14 wherein said first and second conductivity types are n-type and p-type, respectively.

Claim 22

A multijunction photovoltaic device, comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer is a microcrystalline hydrogenated silicon compound doped with an n-type dopant to form a tunnel junction with said top layer and an ohmic contact with said bottom layer.

Claim 23

A multijunction photovoltaic device, comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer is a microcrystalline hydrogenated silicon compound doped with an n-type dopant to form a tunnel junction with said top layer and an ohmic contact with said bottom layer.

Claim 24

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of first and second sublayers doped with an n-type dopant, said first sublayer consisting of an amorphous hydrogenated silicon compound and said second sublayer consisting of a microcrystalline hydrogenated silicon compound, said first sublayer forming an ohmic contact with said bottom layer and said second sublayer forming a tunnel junction with said top layer.

Claim 25

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of first and second sublayers doped with an n-type dopant, said first sublayer consisting of an amorphous hydrogenated silicon compound and said second sublayer consisting of a microcrystalline hydrogenated silicon compound, said first sublayer forming an ohmic contact with said bottom layer and said second sublayer forming a tunnel junction with said top layer.

Claim 26

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of first layer and a second layer, said first layer being doped with an n-type dopant and forming an ohmic contact with said bottom layer, said second layer being dopes with a p-type dopant and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, and said first layer comprises a microcrystalline hydrogenated silicon compound and said second layer comprises an amorphous hydrogenated silicon compound.

Claim 27

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of first layer and a second layer, said first layer being doped with an n-type dopant and forming an ohmic contact with said bottom layer, said second layer being dopes with a p-type dopant and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, and said first layer comprises a microcrystalline hydrogenated silicon compound and said second layer comprises an amorphous hydrogenated silicon compound.

Claim 28

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with an n-type dopant and forming an ohmic contact with said bottom layer, said second layer being doped with a p-type dopant and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, and said first layer comprises an amorphous hydrogenated silicon compound and said second layer comprises a microcrystalline hydrogenated silicon compound.

Claim 29

A multijunction photovoltaic device comprising: a first photovoltaic cell comprising layers of hydrogenated amorphous silicon including a first cell top p-type layer, a first cell middle intrinsic layer, and a first cell bottom n-type layer; a second photovoltaic cell comprising layers of hydrogenated amorphous silicon including a second cell top p-type layer, a second cell middle intrinsic layer, and a second cell bottom n-type layer; said first cell bottom layer and second cell top layer respectively having first and second bandgaps; and an interface layer of a semiconductor compound including silicon disposed between and in contact with said first cell bottom layer and said second cell top layer, said interface layer having a third bandgap smaller than said first and second bandgaps, wherein said interface layer consists of a first layer and a second layer, said first layer being doped with an n-type dopant and forming an ohmic contact with said bottom layer, said second layer being doped with a p-type dopant and forming an ohmic contact with said top layer, a tunnel junction being formed between said first and second layers, and said first layer comprises an amorphous hydrogenated silicon compound and said second layer comprises a microcrystalline hydrogenated silicon compound.