STRUCTURAL CHARACTERIZATION OF LOW-TEMPERATURE MOLECULAR-BEAM EPITAXIAL IN0.52AL0.48AS/INP HETEROLAYERS

A systematic study of the structural quality and arsenic content of as-grown In0.52Al0.48As/InP layers deposited on InP by molecular beam epitaxy at temperatures between 150 and 450-degrees-C was performed using transmission electron microscopy and particle-induced x-ray emission. We found that the amount of As incorporated in the layers generally increases with decreasing growth temperature, with the crystalline quality of the layers being good at growth temperatures higher than 200-degrees-C. At 150-degrees-C, a large density of pyramidal defects is formed, the defects are related to the very large amount of excess As incorporated into the layer. The mechanisms leading to the formation of these defects are discussed. At 200-degrees-C, however, the amount of excess As is lower than expected, and wavy streaks of diffuse scattering are seen in electron diffraction. It is shown that small ordered domains of the CuPt type on the group III atoms are responsible for these features.