ZnO based visible–blind UV photodetector by spray pyrolysis

Photoswitching characteristic of ZnO UV photodetector. [Display omitted] •ZnO based MSM UV photodetectors are synthesized by spray pyrolysis method.•Effect of solution concentration on UV sensing properties is studied.•The dependence of photocurrent on the intensity of incident UV light.•The UV photodetectors device shows maximum photoresponse in UV-A region. Zinc oxide (ZnO) metal–semiconductor–metal ultraviolet photodetectors were fabricated by economical spray pyrolysis method. The devices have been characterized to investigate the effect of precursor solution concentration on the photoconductive properties of ZnO. The structural, morphological and optical properties of the ZnO thin films were studied using different techniques. The crystal structure, size and lattice parameters have been estimated by X-ray diffraction (XRD) analysis. The UV photodetector device prepared using 0.1M solution concentration exhibits low dark current and high UV photocurrent of about 134μA at 5V bias at 365nm peak wavelength. The surface morphology and the surface roughness have been studied by AFM analysis. UV–Vis measurements have been used to study the effect of solution concentration on absorption spectra and hence on the band gap. The present device shows fast response in UV region of electromagnetic spectrum and shows almost no response to visible light. The characteristic times for rise and fall of the photocurrent device were 12s and 9s respectively. This devices are providing a simple and economical way to fabricate high-performance ‘visible–blind’ UV detectors and promising for use in large-area UV-A photodetector applications.