Preparation and characterization of multilayer AlGaAs/GaAs structures for photovoltaic application

In this paper, we present the preparation of multilayer AlGaAs/GaAs heterostructures for photovoltaic application. The structures developed consist of several layers grown on a highly conducting GaAs substrate: n-GaAs base, p-GaAs emitter embedded between two AlGaAs layers, and heavily doped p⁺GaAs capping contact layer. The second 0.03 μm thick 'window' AlGaAs layer has band gap energy of 2.1 eV and ensures penetration of the higher-energy photons in the active region of the p-n junction. The electrical and optical parameters of the multilayer heterostructure as well as the layers thickness are designed by numerical simulation using computer modeling. The optimized heterostructure has a back-surface-field AlGaAs layer of several microns and an ultra thin (20-40 nm) window layer providing the best conversion efficiency and a maximum spectral response in the range 300-900 nm.