Optical Properties Of Arsenic Sulfide Films Fabricated By Reaction Of Arsenic Trichloride And Thiourea In N-propylamine Solution
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Date
2018
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Oum-El-Bouaghi University
Abstract
this paper deals with two approaches for the application of arsenic sulphide layers from solutions. First approach, a new one, is based on chemical reaction of arsenic trichloride and thiourea in n-propylamine. The second approach used for the comparison with the first one employs arsenic sulphide solutions prepared by dissolving of powder of As2S3 in n-propylamine. By using both the approaches input As2S3 solutions with concentrations of 0.33, 0.40 and 0.50 mol/l were fabricated and applied onto glass slides by dip-coating method with a withdrawing velocity of 100 mm/min. Applied layers dried in vacuum at 60 °C and thermally treated at 180 °C for 30 s were characterized by optical and atomic force microscopy as well as by transmission spectroscopy in a wavelength range of 200-2500 nm. From UV,VIS and NIR spectra refractive indices, thicknesses and band gaps were estimated. A maximum refractive index of about 2.2 at 700 nm and thicknesses up to 400 nm were determined on films fabricated from input solutions obtained by the As2S3 dissolving. On the other hand, hybrid organic-arsenic sulphide layers with refractive indices around 1.56 at 650 nm and thicknesses from 2 to 7 µm were prepared from input solutions based on the chemical reaction. Optical bandgaps in a range of 2.18-2.36 were determined. Layers from both the solution types are transparent in a wavelength range of 500-2500 nm. Differences between both types of the films are explained by organics remaining in the layers fabricated by the chemical reaction.
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Keywords
arsenic sulfide, reaction, arsenic trichloride and thiourea, dip-coating, refractive indices, photonic band gap