ELECTROREFLECTANCE DETERMINATION OF THE BAND PROFILE OF A ZNSE/N+GAAS HETEROJUNCTION

Electrolyte electroreflectance (EER) is used to investigate the interface between undoped ZnSe and heavily n-doped GaAs. The evolution of the signal with bias allows an identification of the various features in the EER spectra. The spectra allow us to determine the band profile of the heterojunction, which consists of 100 nm of unintentionally doped ZnSe grown by molecular beam epitaxy on n + GaAs:Si. The band profile that we obtain differs from previously proposed models for the band profile, but explains the transport results that motivated those models. In particular, due to the interdiffusion of Zn and Ga atoms, it displays a strongly p-type region in the GaAs near the interface and an n-type region extending of the order of 5 nm into the ZnSe from the interface.