Development of highly sensitive UV sensor using morphology tuned ZnO nanostructures Muhammad Amin • Nazar Abbas Shah • Arshad Saleem Bhatti Received: 1 April 2014 / Accepted: 29 August 2014 / Published online: 11 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract We report synthesis, electrical, optical, and UV sensing properties of morphology tuned one-dimensional ZnO nanostructures. Morphology tuning was achieved by varying the temperature using very simple vapor transport method. The structural, morphological, and compositional properties of the samples were investigated by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy dispersive analysis of X-rays spectroscopy. Photoluminescence and diffused reflectance spectroscopy were used to optically character- ize films. The structural and morphological features revealed demonstrated that the synthesized nanostructures were high-density crystalline nanowires, nanorods, and nanobelts. Synthesized nanostructures were employed in UV sensing applications. The photosensors exhibit a cur- rent response range from 5 to 217 lA for UV light (365 nm) at room temperature. The sensor showed a rela- tively fast temporal response (0.25–35 s) and baseline recovery time (1–12 s) when irradiated with UV light. Response measurements showed that such a sensor is suitable for use as an optical switch. 1 Introduction One-dimensional (1D) nanostructures have attracted great interest in last two decades due to their outstanding prop- erties and potential applications [1–3]. ZnO is an ideal UV- sensitive semiconductor for optoelectronic applications due to its wide band gap (3.37 eV), large exciton binding energy (60 meV) at 300 K and its capability to operate in harsh environments at high temperature [4–8]. ZnO has been reported as potentially strong UV sensing material [9] over a wide range of applications in military and non military arenas [10] which includes flame sensors, UV source monitoring, and missile plume detection [11]. 1D ZnO nanostructures can be synthesized by numerous syn- thesis methods such as electrochemical, vapor phase, and liquid phase techniques [12, 13]. These methods can pro- duce various configurations of nanostructures including nanowires, nanobelts, nanorods, nanosheets, and nanopar- ticles etc. depending upon the different parameters such as temperature, time, gas flow rate, substrate, catalyst layer etc. Vapor transport is the simplest route to obtain large- density nanostructures, single-crystalline nanostructures, and high aspect ratio of the resulting nanostructures [14]. Recently, one-dimensional ZnO nanowires, nanobelts, and nanorods have shown potential as next-generation UV sensors as well as self-powered photodetectors [5, 15, 16]. UV sensors are highly desirable in many fields such as environmental studies, space communications, medical, and communication equipment [17, 18]. ZnO nanostruc- tures are potential candidate for UV sensors due to their high surface to volume and ON/OFF current ratios [2], fast M. Amin  N. A. Shah (&) Thin Films Technology Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad, Pakistan e-mail: nabbasqureshi@yahoo.com; nazar_abbas@comsats.edu.pk M. Amin e-mail: aminislamabad@yahoo.com A. S. Bhatti Department of Physics, Centre for Micro and Nano Devices, COMSATS Institute of Information Technology, Islamabad, Pakistan e-mail: asbhatti@comsats.edu.pk 123 Appl. Phys. A (2015) 118:595–603 DOI 10.1007/s00339-014-8764-x