Controlled growth of (100) or (111) CdTe epitaxial layers on (100) GaAs by molecular beam epitaxy and study of their electron spin relaxation times

Abstract

The authors demonstrate control of the crystalline orientation [(100) or (111)] of molecular beam epitaxy-grown CdTe films on (100) ZnSe/GaAs substrates. Reflection high-energy electron diffraction is used to observe the nucleation of the epitaxial layers in situ during growth. X-ray diffraction and photoluminescence measurements indicate that in both cases, the CdTe film is of high structural quality despite the large lattice constant mismatch of 14.3% between CdTe and ZnSe. They also use time-resolved Kerr rotation to monitor the electron spin dynamics in these films. While the spin lifetime is found to depend on material quality, only (100) films show a clear temperature dependence, a peculiar feature they believe to arise from residual strain.