Reflection High-Energy Electron Diffraction Image Analysis during Molecular Beam Epitaxial Growth of InAs/AlGaAsSb Deep Quantum Well Structures

Abstract

We have investigated the lattice strain relaxation during the initial stage of Alx Ga1-x AsSb (0<x<0.5) growth on GaAs (100) substrates by molecular beam epitaxy (MBE). Using time-resolved reflection high-energy electron diffraction (RHEED) image analysis, we have found that AlGaAsSb on a GaAs surface quickly relaxes within 3 to 7 monolayers (MLs). We have also observed that two-dimensional (2D) growth occurs after deposition of 20MLs of GaAsSb on GaAs surfaces. Furthermore, we have confirmed the InAs grows on AlGaAsSb two-dimensionally because AlGaAsSb is lattice matched to InAs. With a total thickness of less of than 700 nm in the InAs/AlGaAsSb deep quantum wells (DQWs), we have achieved very high electron mobilities of more than 32,000 cm2/(V·s) at room temperature.