Photovoltaic device including an intermediate layer

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.