Solvothermal growth of aligned SnxZn1-xS thin films for tunable and highly response self-powered UV detectors

Abstract

In this study, well-aligned SnxZn1-xS (0 ≤ x ≤ 0.12 mol) nanostructured thin films were successfully grown on the glass substrate by a solvothermal method for ultraviolet detector applications. XRD results revealed a hexagonal wurtzite structure for all the SnxZn1-xS thin films. Through structural and morphological studies, as the Sn-content increases, the c-axis orientation became stronger. A comprehensive investigation of the morphological evolution also confirmed a considerable influence of Sn2+ incorporation on the growth mechanism and shape of the SnxZn1-xS nanostructures. The optical measurements indicated that as the Sn-content increases, a linear relationship between the band gap and Urbach energy was found, in which the band gap energy experienced a significant decrease from 4.20 to 3.83 eV; whereas the Urbach energy was dramatically broadened. A gradual increase was observed in the intensity of photoluminescence spectra, in which three prominent emission peaks were found, indicating a successful formation of the SnxZn1-xS nanostructures. The photosensing performance of the samples was studied for the first time. The ultraviolet detectors based on the Au/SnxZn1-xS thin film junctions featured an excellent rectification behavior and attractive photovoltaic effect under UVB exposure. The enhancing effects of annealing treatment on the photoelectric behavior of the samples were also noted. The photoresponse characteristics of the self-powered ultraviolet detectors exhibited a high Ion/Ioff ratio > 103 and a fast photoswitching speed with superior stability and reproducibility at zero voltage. Additionally, notable photosensitivity and detectivity of more than ∼20 times are achieved at the self-powered mode.