Defect analysis of sprayed β-In2S3 thin films using photoluminescence studies

Abstract

In this paper we report for the first time the results of photoluminescence (PL) studies on thin films of a β-In2S3 compound semiconductor, grown using a chemical spray pyrolysis (CSP) technique. PL emission in the wavelength range 550–900 nm was recorded using a 488 nm line from a Ar+ laser as the excitation source. There were two PL bands, centred at 568 nm (band A) and 663 nm (band B). A shift in the PL peak energy and full width at half maximum of the former band due to a variation in temperature strongly suggested that the emission followed the Cartesian coordinate (CC) model of luminescence, while the latter was found to have arisen from transitions between a donor–acceptor pair. Band A was most dominant in the sulfur-deficient sample and hence associated with a sulfur vacancy, while band B was dominant in the indium-rich sample and hence linked with indium interstitials. The proposed energy level scheme allowed us to interpret the recombination processes in β-In2S3 thin films.