A GaAs/AlAs/GaAs/AlAs/Ge heterostructure grown on a Si/Al2O3(1\(\bar {1}\)02) substrate is formed and studied. The Ge buffer layer is produced by the “hot wire” technique, whereas the III–V layers are grown by metal–organic vapor-phase epitaxy. The optical quality of the III–V layers is determined by photoluminescence spectroscopy. Structural studies are performed by high-resolution transmission electron microscopy. The elemental composition is determined by energy-dispersive X-ray spectroscopy. In the study, the possibility of growing a single-crystal GaAs layer on a Si/Al2O3 substrate through AlAs/GaAs/AlAs/Ge buffer layers is shown.