Thin absorber layer of a photovoltaic device
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 heterojunction comprising a n-doped GaAs layer directly adjacent to a p + -doped AlGaAs layer; and an interface layer comprising a Group III-V compound semiconductor above the p + -doped AlGaAs layer,
wherein recesses are formed in the p + -doped AlGaAs layer,
wherein the p + -doped AlGaAs layer forms an absorber layer having a thickness less than 800 nm such that electric energy is created when photons are absorbed,
wherein the doping density in the n-doped GaAs layer is lower than in the p + -doped AlGaAs layer such that electrons in the n-doped GaAs layer have a higher mobility than the mobility of holes in the p + -doped AlGaAs layer, and
wherein the p + -doped AlGaAs layer comprises a plurality of p + -doped AlGaAs layers wherein each of the plurality of p + -doped AlGaAs layer comprises a different percentage of aluminum.
2. The photovoltaic device of claim 1 , wherein the n-doped GaAs layer has a thickness in a range from about 300 nm to about 3500 nm.
3. A photovoltaic device, comprising:
a heterojunction comprising a n-doped GaAs layer directly adjacent to a p + -doped AlGaAs layer; and an interface layer comprising a Group III-V compound semiconductor above the p + -doped AlGaAs layer,
wherein recesses are formed in the p + -doped AlGaAs layer,
wherein the p + -doped AlGaAs layer has a doping profile tuned such that doping levels increase from a first side of the p + -doped AlGaAs layer to a second side,
wherein the doping density in the n-doped GaAs layer is lower than the p + -doped AlGaAs layer such that electrons in the n-doped GaAs layer have a higher mobility than the mobility of holes in the p + -doped AlGaAs layer,
wherein the p + -doped AlGaAs layer forms an absorber layer and has a thickness less than 800 nm such that electric energy is created when photons are absorbed, and
wherein the p + -doped AlGaAs layer comprises a plurality p + -doped AlGaAs layers.
4. The photovoltaic device of claim 3 , wherein each of the plurality of p + -doped AlGaAs layers comprises a different percentage of aluminum.
5. The photovoltaic device of claim 3 , wherein the n-doped GaAs layer has a thickness in a range from about 300 nm to about 3500 nm.
6. The photovoltaic device of claim 3 , wherein the n-doped GaAs layer has a doping level of 2×10 17 cm −3 .
7. The photovoltaic device of claim 3 , wherein the p + -doped AlGaAs layer has a doping level of 1×10 19 cm −3 .