ZnTe/GaAs(001): Growth mode and strain evolution during the early stages of molecular-beam-epitaxy heteroepitaxial growth

Abstract

The initial stages of molecular-beam-epitaxy heteroepitaxial growth of ZnTe on GaAs(001) substrates are studied by in situ grazing incidence x-ray diffraction performed under ultrahigh vacuum. Pseudomorphic fully strained layers are observed for deposits up to 4 molecular layers (ML), whereas plastic relaxation starts after a critical thickness of about 5 ML together with the onset of a three-dimensional growth mode. Evidence for a normal strain gradient is obtained in partially relaxed layers. The results are confirmed by ex situ high-resolution transmission electron microscopy.