Photovoltaic device including an intermediate layer
View Patent ↗Methods and apparatus are provided for converting electromagnetic radiation, such as solar energy, into electric energy with increased efficiency when compared to conventional solar cells. In one embodiment of a photovoltaic (PV) device, the PV device generally includes an n-doped layer and a p + -doped layer adjacent to the n-doped layer to form a p-n layer such that electric energy is created when electromagnetic radiation is absorbed by the p-n layer. The n-doped layer and the p + -doped layer may compose an absorber layer having a thickness less than 500 nm. Such a thin absorber layer may allow for greater efficiency and flexibility in PV devices when compared to conventional solar cells.
1. A photovoltaic device, comprising:
a n-doped GaAs layer;
a p + -doped AlGaAs layer wherein recesses are formed in the p + -doped AlGaAs layer;
a n-doped AlGaAs intermediate layer interposed between the n-doped GaAs layer and the p + -doped AlGaAs layer, wherein the n-doped intermediate AlGaAs layer and the p + -doped AlGaAs layer form a p-n junction such that electric energy is created when photons are absorbed by the p-n junction, and wherein the n-doped AlGaAs intermediate layer provides a transition between the n-doped GaAs layer and the p + -doped AlGaAs layer; and
an interface layer comprising a Group III-V compound semiconductor above and indirect contact with the p + -doped AlGaAs layer, wherein a length in the horizontal direction of the p + -doped AlGaAs layer is longer than a length in the horizontal direction of the interface layer.
2. The photovoltaic device of claim 1 , wherein the p + -doped AlGaAs layer has a doping profile fine-tuned such that doping levels change from one side of the p + -doped AlGaAs layer to the other.
3. A photovoltaic device, comprising:
a n-doped GaAs layer;
a p + -doped AlGaAs layer, wherein recesses are formed in the p + -doped AlGaAs layer;
a n-doped AlGaAs intermediate layer comprising a plurality of layers wherein each of the plurality of layers comprises a different percentage of aluminum, the n-doped AlGaAs layer is interposed between the n-doped GaAs layer and the p + -doped AlGaAs layer, wherein the n-doped intermediate AlGaAs layer and the p + -doped AlGaAs layer form a p-n junction such that electric energy is created when photons are absorbed by the p-n junction, and wherein the n-doped AlGaAs intermediate layer provides a transition between the n-doped GaAs layer and the p + -doped AlGaAs layer; and
an interface layer comprising a Group III-V compound semiconductor above and indirect contact with the p + -doped AlGaAs layer, wherein a length in the horizontal direction of the p + -doped AlGaAs layer is longer than a length in the horizontal direction of the interface layer.
4. The photovoltaic device of claim 3 , wherein the thickness of the n-doped GaAs layer from about 300 nm to about 3500 nm.
5. The photovoltaic device of claim 3 , wherein the n-doped layer has a doping level of 5×10 16 to 5×10 17 cm −3 .
6. The photovoltaic device of claim 3 , wherein the n-doped AlGaAs intermediate layer comprises a graded aluminum composition.