Epitaxial growth of γ-InSe and α, β, and γ-In 2 Se 3 on ε-GaSe

We demonstrate that γ -InSe and the α , β and γ phases of In 2 Se 3 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 x Se 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 x Se y layers, which are aligned over large areas. The In x Se y epilayers are characterised using Raman, photoluminescence, x-ray photoelectron and electron dispersive x-ray spectroscopies. Each In x Se 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.