Hydrothermal assisted chemical bath deposition of (Cd:Zn)S thin film with high photosensitivity and low dark current

Abstract

In this work we observed high-quality nanocrystalline ternary films obtained by hydrothermal assisted chemical bath deposition on glass substrates. Deposition has been carried out at 200 °C for one hour. The alloying effect and the photoelectric properties of the material is enumerated in this paper along with the structural, Optical, morphological and photoluminescence properties. The structural properties analysed by X-ray diffraction (XRD) reveals the hexagonal phase of CdZnS film with preferred orientation along the (1 0 0) plane and the average grain size was observed to be 28 nm. Scanning electron microscopy (SEM) images showed clusters of nanofibers grown on the film. The optical bandgap obtained from the optical absorption studies using UV–Vis-NIR spectroscopy was 2.98 eV. Broad and asymmetric emission from intrinsic point defects was observed in the PL spectrum recorded using Fluromax-4Spectrofluorometer. The photoconductivity of the film was investigated by using Keithley SMU2450 four probe source measure unit under illumination by light from 300 W/82 V halogen lamp. In the dark condition, the I–V Curve showed non-linear behaviour, whereas the film showed ohmic behaviour under illumination. The photoresponse of the film was recorded at intervals of 100 s. The photocurrent increased under illumination and the current recovered to the original dark level when light was switched off. Under 100 s of illumination the photocurrent increased and became almost constant. This work presents a simple way to obtain photodetectors and will benefit in the manufacture of optoelectronic devices.