TANDEM SOLAR CELL WITH IMPROVED TUNNEL JUNCTION
A photovoltaic device and method for fabricating a photovoltaic device include forming a light-absorbing semiconductor structure on a transmissive substrate including a first doped layer and forming an intrinsic layer on the first doped layer, wherein the intrinsic layer includes an amorphous material. The intrinsic layer is treated with a plasma to form seed sites. A first tunnel junction layer is formed on the intrinsic layer by growing microcrystals from the seed sites.
1 . A photovoltaic device, comprising:
a light-absorbing semiconductor structure including a first doped layer, an intrinsic layer and a first tunnel junction layer, the intrinsic layer including an amorphous material phase; and
an interface between the intrinsic layer and the first tunnel junction layer including a seed layer to enable microcrystalline growth of the first tunnel junction layer and a second first tunnel junction layer.
2 . The photovoltaic device as recited in claim 1 , further comprising a transmissive substrate on which the semiconductor structure is formed.
3 . The photovoltaic device as recited in claim 2 , the transmissive substrate further comprising a transparent electrode.
4 . The photovoltaic device as recited in claim 1 , wherein the intrinsic layer includes amorphous silicon and the first and second tunnel junction layers include microcrystalline silicon.
5 . The photovoltaic device as recited in claim 1 , wherein the photovoltaic device is included in a stack of photovoltaic devices.
6 . The photovoltaic device as recited in claim 5 , wherein the stack of photovoltaic devices includes band gap splitting.
7 . The photovoltaic device as recited in claim 1 , wherein the first and second tunnel junction layers include ultra-thin doped layers each having a thickness of between about 0.1 nm and about 20 nm.
8 . The photovoltaic device as recited in claim 1 , wherein the first and second tunnel junction layers include a microcrystalline phase having additional dopants beyond a capability of an amorphous phase to improve conductivity.