PHOTOTHERMAL DEFLECTION ANALYSIS OF β-In2S3 THIN FILMS: THE EFFECT OF S/In MOLAR RATIOS
Abstract
β-In2S3 thin films (S/In=1, 2 and 4) were prepared using the pneumatic spray pyrolysis (PSP) route to analyze the effect of the S/In ratio on the physical properties. These properties were conducted using the photothermal deflection spectroscopy (PDS) method. The PDS signal amplitudes as a function of wavelength show multiple reflections which appear for all prepared In2S3 films. Such multiple reflections indicate homogeneity and high crystalline quality of the films. The deduced values of the optical band gap vary in the range 2.55–2.65eV. The highest thermal diffusivity is obtained for S/In=2. The product (μ⋅τ) is found in order of 10−8cm−1/V. The estimated carrier diffusion lengths are 0.06, 0.11 and 0.09μm for films corresponding to S/In=1, 2 and 4, respectively. Defect absorption in β-In2S3 films is also investigated by PDS. Five absorption peaks are observed. These absorption peaks contain defect information in the band gap. Hence, this work evidences that β-In2S3 is a multi-functional material that can be used in optoelectronic, photovoltaic and visible-irradiation photocatalyst applications.
