The InSb Epitaxial Growth On GaAs Substrate By Molecular Beam Epitaxy And Its Structure And Properties

Molecular Beam Epitaxy (MBE) has been used to grow InSb heteroepilayer on GaAs (001) substrate with optimized low temperature buffer layer. The surface morphology and crystal quality of InSb epilayers have been investigated by means of atomic force microscope (AFM), scanning electron microscopy (SEM) and double crystals X-ray diffraction (DCXRD). The kinetic Monte Carlo method based on a solid-on-solid model has been introduced to simulate the InSb heteroepitaxial growth. Furthermore, transmission electron microscopy (TEM) and Hall measurements have been performed to study the interface structure and electrical properties of InSb epilayers.The reflection high-energy electron diffraction (RHEED) was used to monitor the surface of InSb in situ during the epitaxial growth, RHEED diffraction pattern indicates Volmer-Weber growth at the very early stage of nucleation. In addtion, the growth rate of low temperature InSb buffer layer was 0.26μm/h, which was obtained by RHEED intensity oscillation curves. Growth temperature of InSb epilayers were investigated with SEM and DCXRD, and it was found that the optimum temperature was 440℃. A 2.1μm InSb layer grown at 440℃had an X-ray rocking curve of 412 arcsec, the strain relaxtion was about 99.02%.In order to deal with large mismatch (14.6% at room temperature) between GaAs and InSb, a InSb buffer layer was deposited firstly at low temperature 350℃, followed by a InSb epilayer being deposited at higher temperature 440℃. The results shown that, the optimum InSb buffer layer thickness was 40nm. With this parameter, room temperature mobilities as high as 4.35×10⁴cm²V^-1s^-1 were measured in InSb epilayer of 1.2μm, while the carrier concentration about 1.6×10¹⁶cm^-3. TEM studies of the interface confirmed that the mismatch is accommodated by generation of misfit dislocation network with space 3.5nm. The high density dislocations behave like deep-level donors and the dislocations scattering is considerable at low temperature especially.Besides, when the InSb buffer layer thickness became 80nm, the roughness of InSb epilayer increased. The initial stage of InSb growth on GaAs substrate is...