Structural and optical properties of InAs/AlSb strained-layer superlattices (SLSs) grown by molecular-beam epitaxy (MBE) are described. Either an interface bond of InSb or AlAs was selectively made in the SLSs by controlling the beam supply sequence during growth. Characterization of the SLSs was performed using Raman scattering and photoluminescence (PL) spectroscopy in addition to the in situ analysis of reflection high-energy electron-diffraction signals. The Raman signals consisted of three different types of lattice vibrations: InSb- or AlAs-like phonons localized at the interface bonds, InAs- and AlSb-like optic phonons confined in the respective layers, and zone-folded acoustic phonons extending through the constituent layers. The energy shift of the optic phonons was used to determine the strain in SLSs. This analysis revealed a considerable dependence of the SLS structure on the interface bond. The Raman analysis was also supported by the PL data. These optical properties are discussed in relation to the MBE-growth conditions of SLSs.

This paper describes an experimental analysis of strained InAs/AlSb ultrathin-layer superlattices (ULSs) grown by MBE. Interface bonds of InSb or AlAs were selectively made in the ULSs by controlling the beam supply sequence during growth. Structural analysis was performed for ULSs on both InAs and AlSb buffer layers using Raman scattering. This analysis revealed that each constituent in the ULSs was relaxed individually only when the AlAs interface bond was combined with the AlSb buffer layer. Other combinations of the interface bond and buffer layer, however, resulted in a free-standing superlattice structure. These experimental results are consistent with the interface dependence of electron mobility reported for InAs/AlSb single quantum well structures.