Optical Anisotropy of ZnSe/BeTe Superlattices Probed by Excitonic Spectroscopy

Abstract

A number of publications devoted to studies of optical anisotropy of heterostructures with no-common atom at interfaces (InAs/GaP, etc.) has been published recently [1-3]. This effect is attributed to a low local syinmetry of a single interface between two different zinc-blende type structures. In heterostructures CA/C'A' (001) with no-common cations (C ≠ C') and anions (A ≠ A'), an interface consists of the two atomic planes with A—C' or A'—C bonds. In this case there exist four different types of quantum-well structures (QWs) and superlattices (SLs). The structures with similar interfaces have the D2d point symmetry and are optically isotropic in the plane of interfaces. If the bonds at the left and right interfaces are different, an ideal structure with no-common atom is characterized by the in-plane anisotropy with the principal axes [110] and [110]. The microscopical reason for this in-plane anisotropy is a mixing of heavy hole and light hole states at the interfaces [3, 4]. In this paper we present an experimental study of the in-plane optical anisotropy in novel ZnSe/BeTe type-II quantum-well structures. Samples were grown by MBE on (100)-oriented GaAs substrates with controlling the type of interfaces. Three types of ZnSe/BeTe (100/50 Α) x 20 samples were grown: with BeSe...BeSe, ZnTe. . .ZnTe and BeSe...ZnTe interfaces. Basic optical properties of excitonic transitions in the ZnSe/BeTe quantum well structures were reported recently in Refs. [5, 6]. The observed two photoluminescence lines with energy positions at ,^s 2.8 eV and 2.0 eV were related to a