Effect of annealing on the structural and optical properties of InSe bilayer thin films

InSe bilayer thin films with different thickness were prepared on to a glass substrate by sequential thermal evaporation. Preparation and post deposition treatment conditions were optimized in order to achieve effective bilayer mixing. The influence of bilayer film thickness and annealing temperature on the structural and optical properties was investigated. The prepared films were characterized by X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray analysis, UV-Visible spectroscopy, photoconduction and resistivity measurement. Structural studies show that the material undergoes phase transition with thickness, due to co-existence of many phases. Morphological analysis revealed that Se content plays an important role in determining the surface morphology of the film. It has been observed that grain growth and grain splitting phenomena depend on film thickness and annealing temperature. From the photoconduction measurements, the photocurrent increases rapidly when the sample is illuminated using 135 K Lux of white light. Absorption coefficient is in the order of 10⁴ cm⁻¹, makes the InSe thin film useful for the preparation of absorber layer in hybrid solar cell.