Abstract
The present work demonstrates the impact of thermal annealing on the structural, linear, and non-linear optical characteristics of thermally evaporated BixIn35-xSe65 (x = 0, 5, 10, 15 at%) thin films. The prominent crystalline phases have been developed for all annealed films at 450 °C whereas the films remain amorphous at 350 °C annealing. The XRD and Raman analysis showed the phase transformation of Bi-doped films and new Bi2Se3 phases developed upon annealing at 450 °C. The phase transformation induced change increased the linear and nonlinear properties with great extent as seen from the UV–visible optical studies. The direct and indirect optical bandgaps decreased with annealing temperature and also with Bi % content due to the formation of surface dangling bonds near the crystallite sites. The static linear refractive index and high-frequency dielectric constants were increased with annealing. The third-order non-linear susceptibility and non-linear refractive index were found to be greatly influenced by annealing temperature and increased with bismuth content. The FESEM micrographs also showed the phase transformation and EDX analysis showed the composition. The results obtained from the materials showed the potentiality to be useful for photovoltaic and optoelectronic applications.
Highlights
The present work demonstrates the impact of thermal annealing on the structural, linear, and nonlinear optical characteristics of thermally evaporated BixIn35-xSe65 (x = 0, 5, 10, 15 at%) thin films
We have studied the doping effect of bismuth into BixIn35-xSe65 thin films prepared by thermal evaporation technique which showed the presence of crystallinity behavior in 7% and 15% Bi-doped films with significant modification in linear and non-linear optical characteristics[21]
The objective of the present study is to investigate the annealing induced effects on the linear and nonlinear optical parameters such as absorption coefficient, extinction coefficient, optical band gap, static refractive index, third-order optical susceptibility, nonlinear refractive index of thermally evaporated B ixIn35-xSe65 (x = 0, 5, 10, 15 at %) thin films at 350 °C and 450 °C annealing temperatures
Summary
The phase transformation induced change increased the linear and nonlinear properties with great extent as seen from the UV–visible optical studies. The annealing induced large non-linear optical changes in Ge20Se65S15 thin films suggests for use in low-power devices like optical computers, ultrafast switches, and pulsed lasers[14] In this regard, the In–Se (III-VI) system is considered as an archetypical semiconducting chalcogenide that takes an important place in applications such as electrical switching, nonlinear optics, diodes, photodetectors[15,16]. The annealing effect on the Se85In15-xSbx films at temperatures above Tg showed improved linear optical properties of the host matrix which is due to the structural rearrangement that occurred from amorphous to crystalline transformation[18]. The annealing induced changes in higher Bi% and the changes in nonlinear parameters such as non-linear refractive index and third-order non-linear susceptibility with annealing is the prime aim of the present work
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