Chemical bath deposited ZnO thin film based UV photoconductive detector Shahin K. Shaikh, Sumayya I. Inamdar, Vinayak V. Ganbavle, Kesu Y. Rajpure * Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, India article info Article history: Received 7 November 2015 Received in revised form 23 December 2015 Accepted 27 December 2015 Available online 29 December 2015 Keywords: Zinc oxide MSM UV photodetector Chemical bath deposition Ohmic contact Photoresponse abstract Ag/ZnO/Ag metal-semiconductor-metal (MSM) Ultraviolet (UV) photodetectors based on Zinc oxide (ZnO) thin films are successfully fabricated on the glass substrate by using chemical bath deposition (CBD), which shows the good ohmic contact behavior between metal-semiconductor junctions. The devices are characterized to investigate the effect of deposition time and thickness on the photocon- ductive properties of ZnO thin films. The physiochemical properties of ZnO thin films are carried out. Thin films exhibit hexagonal crystal structure with the preferential orientation along (002) plane. With the applied bias of 5 V, the ZnO based photodetector shows low dark current and high photocurrent of 113.83 mA. The device exhibits relatively high photoresponse with rise time about 9 s and fall time about 21 s. It suggests that ZnO thin films are potential candidates for the UV photodetector application using easy and low-cost fabrication method. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Solar ultraviolet-A (UVA) (320e400 nm) is closely related to human health. The excess amount of UVA radiation causes pre- mature aging and wrinkling; it means the radiation penetrates into the deeper skin layers, where connective tissue and blood vessels are affected. On the other hand, these radiations are also used for the degradation of the various harmful dies [1]. UV photodetector also used in various military and civil applications such as envi- ronmental monitoring and optical communication [2]. Thus to make the use of the advantages and to suppress the disadvantages the detection and quantification of UV A radiation is important. Wide band gap material such GaN, ZnO, TiO 2 , GaP etc. is used to detect the UV radiation due to their special properties such as the band gap energy value of these materials lies in the UV region, with their thermal stability and radiation hardness [3e7]. Among all these materials ZnO based UV photodetector studied extensively because of their outstanding physical and chemical properties [8]. ZnO has various potential applications such as solar cell [9], gas sensors [10], optoelectronic devices [11], biological applications [12] and UV photodetector [13] etc. ZnO has a low material cost and low deposition temperature [14]. It is n-type semiconductor material with wide direct band gap of 3.3 eV and large exciton binding energy of 60 meV, which makes it a suitable candidate for fabrication of UV photodetector [15] as well as UV light emitting diodes [16]. Another main advantage of ZnO is, there is various synthesis method and diverse processing technologies to fabricate ZnO based UV photodetector. Recently there are lots of reports on ZnO UV detector fabricated by using different chemical techniques. Basak et al. fabricated AueZnO MSM junction by using sol gel method [17]. Liang et al. fabricated ZnO MSM UV detector on R-plane sapphire substrates by using metalorganic chemical vapor deposition technique, Ag has been used as contact electrode [18]. Chen and co-workers describe the vapor-liquid-solid deposition technique, using this technique they deposit a ZnO thin film on p-GaN/sapphire substrate, to fabricate p-n heterojunction photodetector [19]. Lin et al. fabricate ZnO UV photodetector by using molecular beam epitaxy. They fabricated both Schottky and MSM photodetector using Ru as contact electrode [20]. In this work, we present the fabrication of Ag/ZnO/Ag metal- semiconductor- metal (MSM) structured UV photodetector de- vices using chemical bath deposition (CBD) method. Among all chemical deposition method CBD represents a simple and effective route for synthesis of ZnO thin films. This CBD technique is based on the controlled chemical reaction in solution which leads to the formation of the films. The morphological, structural and optical properties of ZnO are strongly depending on the deposition * Corresponding author. E-mail address: rajpure@yahoo.com (K.Y. Rajpure). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom http://dx.doi.org/10.1016/j.jallcom.2015.12.226 0925-8388/© 2015 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 664 (2016) 242e249