Molecular-beam epitaxy of two-dimensional gase layers on GaAs(001) and GaAs(112) substrates: structural and optical properties

The results of studies of the structural and optical properties of two-dimensional GaSe layers grown by molecular-beam epitaxy on GaAs(001) and GaAs(112) substrates using a valve cracking cell for the Se source are reported. The influence of the MBE growth parameters (the substrate temperature, Ga flux intensity, Se/Ga incident flux ratio) on the surface morphology of the layers is studied. By means of transmission electron microscopy, electron diffraction technique, and Raman spectroscopy, it is shown that the structure of the GaSe layers corresponds to the $\gamma$-GaSe polytype. From X-ray diffraction analysis, it is established that there exist $\alpha$-Ga$_2$Se$_3$ inclusions in the GaSe layers grown under conditions of high enrichment of the growth surface with Se.