Structural and Optical Properties of GaSe/GaAs(001) Layers Grown by Molecular Beam Epitaxy
This paper reports on molecular beam epitaxy of GaSe 2D-layers on GaAs(001) substrates at growth temperatures of TS ≈ 400–540 ◦C as well as studies of their structural and optical properties. Transmission electron microscopy and the Raman spectroscopy techniques have established a correlation between the molecular beam epitaxy growth conditions and the GaSe polytypes being formed. It has been shown that GaSe layers grown at TS ≈ 400 ◦C can be characterized as a γ-GaSe polytype with a rhombohedral crystal lattice structure, whereas the layers grown at TS ≈ 500 ◦C have a hexagonal structure and possess a ε-GaSe polytype. The latter also exhibit strong near band-edge photoluminescence at T = 300 K. The strong anisotropy of the photoluminescence intensity in an array of GaSe nanoplatelets has been revealed.