Study on optical, electronic and thermal properties of β-In2S3 thin films using photothermal beam deflection technique

Abstract

Photothermal techniques rely on light induced heating mechanisms to evaluate various optical, thermal and electronic properties of materials. In this work, photothermal beam deflection technique is employed to investigate non-radiative transitions occurring within the conduction band and defect bands of β-In2S3 thin films. Heat generation from β-In2S3 thin films is triggered using laser beams of wavelength 488, 532 and 632 nm. A probe laser beam of wavelength 546 nm is used to measure the heat generation and distribution in the samples. Thermal diffusivity (Dth), electronic carrier mobility (μ), lifetime \(\left( \tau \right)\) and surface recombination velocity (Vsr) are measured by fitting the theoretical and experimental photothermal response. The photothermal response and transport properties of the β-In2S3 thin films with varying percentage of chlorine as dopant is studied to understand the role of chlorine. The presence of chlorine in these films have increased the electronic mobilty and carrier lifetime by an order of 10 by passivation of surface defects.