Epitaxial growth of γ-InSe and α, β, and γ-In₂Se₃ on ϵ-GaSe

We demonstrate that γ-InSe and the α, β and γ phases of In₂Se₃ can be grown epitaxially on ϵ-GaSe substrates using a physical vapour transport method. By exploiting the temperature gradient within the tube furnace, we can grow selectively different phases of In_xSe_y depending on the position of the substrate within the furnace. The uniform cleaved surface of ϵ-GaSe enables the epitaxial growth of the In_xSe_y layers, which are aligned over large areas. The In_xSe_y epilayers are characterised using Raman, photoluminescence, x-ray photoelectron and electron dispersive x-ray spectroscopies. Each In_xSe_y phase and stoichiometry exhibits distinct optical and vibrational properties, providing a tuneable photoluminescence emission range from 1.3 eV to ∼2 eV suitable for exploitation in electronics and optoelectronics.