Structural characterization of GaAs grown at low temperatures by molecular beam epitaxy

Abstract

High-resolution X-ray diffraction methods have been used to characterize the structural characteristics of GaAs grown by molecular beam epitaxy at low substrate temperatures. Triple-crystal X-ray diffraction scans demonstrate that, as the As4/Ga incorporation ratio was increased, there occurred increases in the magnitude of diffuse scattering as well as an anisotropy in the scattering. A degradation of the crystal truncation rod is also observed. Differences have also been observed in the diffuse scattering from n- and p-doped GaAs samples grown in this way; we attribute this to changes in the kinetics of arsenic incorporation due to the electrical characteristics of the material. Analysis of the annealed GaAs layers has shown the development of long-range strain fields from distortions generated by the growth of the arsenic precipitates. The diffuse scattering has been used to develop estimates of the average size of the arsenic precipitates.