Tuning in linear and nonlinear optical parameters by interfacial mixing of Sb/Ag2Se bilayer thin films under annealing at different temperatures for optoelectronic applications

Abstract

Semiconducting materials have found enormous interest due to their immense applicability in various optoelectronics fields. In the current report, Sb/Ag2Se bilayer thin film was prepared through thermal evaporation techniques. The thickness of the thin film was 636 nm, where Sb layer of 20 nm was deposited over 616 nm layer of Ag2Se. Bilayer film was annealed at various temperatures for 2hr. The structural study of the material shows the presence of Ag2Se orthorhombic phase. The crystallinity of the material gradually increased with the annealing process. The surface morphology of the material reveals the enhancement in the porosity of the material after annealing. Transmission spectra show a decreased pattern after the annealing process. The optical study showed a red shift in absorption edge and reduced optical bandgap. This may be for the increase in the width of the localised states. Other linear parameters such as skin depth, extinction coefficient and optical density were also estimated from the observed data. The high-frequency dielectric constant and static refractive index increased with annealing temperature, satisfying the Moss rule. 1st and 3rd order non-linear susceptibilities were increased from 0.587 esu to 0.633 esu and 2.02 × 10−11 esu to 2.02 × 10−11 esu, respectively. The surface wettability study of the material shows a transition from hydrophobic to hydrophilic nature. Thiese properties made the sample possible application for self -cleaning material for solar panels or other devices. The observed optical properties of the material prove its applicability to other optoelectronic devices.