Tuning in optoelectronic properties of In/Te bilayer heterostructure upon annealing at different temperatures: surface wettability and photo response study for photonic and solar cell applications.

The current study depicted the influence of annealing temperature on In/Te bilayer thin film of 350 nm synthesized by thermal evaporation method. The interfacial diffusion of In into Te sites at different annealing temperatures (100 °C, 150 °C, 200 °C, 250 °C) modified the structural as well as the electro-optical response of the films. The structural study showed the appearance of an orthorhombic In4 Te3 peak with annealing. The surface texture showed the particle nature with homogeneous distribution with annealing temperatures. The cross-sectional view of the bilayer and annealed film confirmed the formation of In/Te film with a total thickness of 350 nm. Surface mapping images confirm the homogeneous and uniform elemental distribution. The transmission was enhanced with annealing and showed broad transparency over the NIR region, making them suitable for IR device applications. The enhanced optical bandgap with annealing due to induced local structural changes reduced the optical parameters, such as refractive index, dielectric constant, and nonlinear susceptibility. The surface wettability measurements showed an enhanced hydrophobic nature with annealing. The variation of photocurrent with respect to voltage showed an ohmic nature, with enhancement from nA to ∼mA with annealing. Such alteration opened new ways to be used in solar cells, photodetectors, and photonic device applications.