Linear and nonlinear optical studies of indium selenide thin films prepared by thermal evaporation technique

The manuscript concerns linear and nonlinear optical studies of thin indium selenide films are prepared using thermal evaporation technique, which is intensively researched due to its specific characteristics. In the wavelength range, 300–2500 nm, the transmission and reflection spectrum were taken using the VIS-NIR spectrophotometer. For processed films, the nonlinear optical parameters viz. nonlinear refractive index (n₂) and third order nonlinear susceptibilities χ ³have been tested by numerical calculation. The optical band gaps obtained from Tauc's relationship for direct and indirect transitions are within the scope of 3.6 −1.9 eV and 1.55–1.1 eV, respectively, and the band gap expanded with film thickness decreases.