Optical Properties of E-beam Evaporated Indium Selenide (InSe) Thin Films

Indium selenide (InSe) thin films were prepared by electron beam evaporation technique onto glass substrate at a pressure of ~8×10-5 Pa. The deposition rate of the InSe thin films is ~8.30 nms-1. The XRD and SEM study reveal that InSe thin films are amorphous before phase-transition while they become polycrystalline after phase-transition. The Energy Dispersive Analysis of X-ray (EDAX) analysis shows that InSe thin films are non-stoichiometric. The change in electrical conductivity of InSe thin films with temperature shows a semiconducting behavior. The optical properties of both the virgin and phase-transited InSe thin films have been studied in the wavelength range 360<λ<1100nm, respectively at room temperature. The study of absorption coefficient of virgin InSe thin films shows a direct type transition with a band gap of ≈1.65 eV which agrees well with the reported values. The variations of refractive index and dielectric constant of the films were also calculated and discussed in relation with film re-crystallization after heat treatment. The integrated values of luminous and solar transmittance as well as of reflectance suggest that InSe is a potential candidate for the application in selective surface devices.