Search

Built-in electric fields appear during the molecular-beam epitaxy of GaSe on a GaAs(001) substrate at the GaSe/GaAs interface, the presence of the fields is evidenced by Franz–Keldysh oscillations observed in photoreflectance spectra. The varying values of the strength of these fields (from 9.8 to 17.6 kV/cm) can be associated both with the diffusion of Se atoms into the GaAs substrate (buffer layer) and with the formation of transient submonolayers during epitaxial growth. Built-in fields are not observed at the interface of structures grown on GaAs(111)B and GaAs(112) substrates, which can be explained by the lower propagation efficiency of Se into the substrate with mentioned orientations when compared with GaAs(001).

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 γ-GaSe polytype. From X-ray diffraction analysis, it is established that there exist α-Ga2Se3 inclusions in the GaSe layers grown under conditions of high enrichment of the growth surface with Se.