GaAs Molecular Beam Epitaxy on (110)-Oriented Substrates

Molecular-beam epitaxial growth of Si-doped GaAs single-crystal layers on (110)-oriented GaAs substrates has been studied. The surface morphology of grown films was analyzed by scanning electron microscopy and atomic force microscopy, and the crystal structure of grown films was estimated by X-ray grazing incidence diffraction, in-plane pole figures, reciprocal space mapping, and photoluminescence spectroscopy. The type, concentration, and mobility of charge carriers in films were measured by the four-probe method in van der Pauw geometry at temperatures of 300 and 77 K. The possible existence of two areas in growth conditions, where increased concentration and mobility of electrons are achieved, was shown: the first, main area with the highest concentration and mobility values is Tg = 450–500 °C and V/III ratio γ = 20–40, the second, minor one is Tg = 600–680 °C and γ = 40–70. The hole conductivity was obtained at a growth temperature of 580 °C and a low γ value of 16. It was also shown that the defect-free crystal structure of the films grown at high temperatures is not necessarily accompanied by a smooth surface.