Epitaxial Ga2Se3 layers grown on GaAs(100) using a heterovalent exchange reaction

Abstract

III2VI3 compounds were found to form when III–V semiconductors are exposed at elevated temperatures to an excess of group VI elements by an exchange and diffusion reaction of the group V and VI atoms. This simple approach was applied to produce high quality epitaxial Ga2Se3 layers on GaAs(100). Here the optimization of the growth parameters is described. The layers were grown by annealing GaAs(100) substrates in a H2Se atmosphere. The substrate temperature Ts during growth was varied in the range from 600 to 900 K. In addition, the Se partial pressure was varied over more than two orders of magnitude at a fixed Ts. After growth the samples were investigated by x-ray diffraction, Raman, photoluminescence, and secondary ion mass spectroscopies. A phase transition from the α modification of Ga2Se3 with an unordered distribution of vacancies to β-Ga2Se3 with an ordered arrangement of vacancies is observed at Ts≊780 K. A strong green luminescence band peaked at 2.46 eV is discovered at 77 K.