Enhanced photodetectivity and responsivity in In10Se70Te15Bi5 film by time-dependent laser irradiation for photodetector applications

Abstract

Laser treatment for tuning the thin film properties is regarded as a cost-effective, simple, and environmentally friendly method. The recent work aims at the laser annealing of In₁₀Se₇₀Te₁₅Bi₅ film under a 532 nm DPSS laser at variable time scales. The findings from the structural study show an increased dislocation density with reduced crystallite size with irradiation time. The phases like In₂Se₃ and Bi₂Se₃ contributed towards the other optical parameters. The reduction in bandgap by 0.023 eV upon laser irradiation shows laser-induced modification in the films. It enhanced the photocurrent, thus increasing the responsivity to 2.52 × 10⁻³ A W⁻¹ and photo detectivity to 6.51 × 10⁸ Jones upon 60 min laser annealing. The particle size reduction is also evident from FESEM images upon laser treatment. The elemental presence is also confirmed from the EDS analysis, along with the XPS core level peaks, which also present the chemical analysis of the films. The laser-induced surface changes affect the surface wettability in terms of a decrease in contact angle, thus increasing the hydrophilicity. The increased refractive index upon laser treatment enhanced the nonlinear values in terms of susceptibility and refractive index. At the same time, the dielectric constant is enhanced by reducing the optical electronegativity through laser illumination. The reduction in transmission resulted in an increased absorbance, which resulted in the enhancement of optical density and reduction in skin depth. The optical quantities, along with the photo response parameters, are useful for visible light photodetectors.