INTERFACE FORMATION IN INAS AISB AND INAS/ALAS/ALSB QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY/

We have used resonant Raman scattering from both longitudinal-optical phonons and interface modes to study the chemical bonding across the I nAs/AlSb interface in InAs/AlSb quantum wells grown by molecular-beam epitaxy. The effusion cell shutter sequence at the interfaces was sele cted for the deposition of either one monolayer of InSb or two to thre e monolayers of AlAs. In all cases an InSb-like interface mode is obse rved, indicating the preferential formation of In-Sb interface bonds i rrespective of the shutter sequence. The deposition of two or three mo nolayers of AlAs at the InAs/AlSb interface results in the formation o f pseudoternary AlSb1-xAsx barriers rather than binary AlAs interfaces and AlSb barriers, indicating a strong exchange among the group-V ato ms. Normal (AlSb on InAs) and inverted (InAs on AlSb) InAs/AlSb interf aces have also been compared, revealing a much stronger InSb-like inte rface mode for the growth of AlSb on InAs than for the case of InAs gr own on AlSb.