Observation of negative photoresponse in joule-heated Au/Cu2SnS3 ternary chalcogenide thin film deposited by low energy pulsed laser deposition

Gold (Au) nanoparticles trapped within Cu₂SnS₃ (CTS) thin films were effectively deposited on a low-cost glass substrate using a simple pulsed laser deposition of 15 mJ for 5 ns at a 10 Hz repetition rate. The film's structural, morphological, topography, optical, and optoelectronic properties were investigated. Highly crystalline ternary chalcogenide CTS with tetragonal symmetry and 17 nm grain size is prepared. The 110 Ω resistivity of the thin film increases up to 125 Ω indicating a negative photoresponse under visible light excitation. The decrease in the photocurrent is also observed with Cu₂SnS₃/Au/Cu₂SnS₃ sandwich ternary chalcogenide structure at resistivities values from 31 to 35 Ω and a Joule effect influence the presence of plasmonic Au nanoparticle interlayers involved a lower phonon disorder given a higher photoresponse effect as predicted from Urbach energy.