Optical characterization of As–S thin films induced by plasma immersion O− ion implantation

Abstract

In this study, optical constants of different thicknesses of stoichiometric composition As40S60 obtained from transmission spectra were investigated. The effect of exposure to oxygen plasma immersion ion implantation (O−-PIII) on the optical constants of the same samples of different thicknesses was also investigated. It is observed that the O−-PIII treatment can effectively improve the transmission spectra of the samples, particularly in medium and transparent regions; therefore the refractive index decreases. In addition, the optical band gap Egopt was determined before and after PIII from the absorption coefficient values using Tauc's procedure, i.e. from the relationship α hν = K(hν - Egopt )2 where K is a constant. The O−-PIII causes an increase in the energy gap of stoichiometric composition As40S60.