Structural, surface morphological and UV photodetection properties of pulsed laser deposited Mg-doped ZnO nanorods: Effect of growth time

Mg0.05Zn0.95O (MZO) nanorod (NR) array films have been successfully grown on SiO2/n-Si substrates by pulsed laser deposition (PLD) without any seed layer. The effect of growth time (15-60 min) on the structural, surface morphological and UV sensing properties of the aligned MZO NRs were studied. All the samples exhibit the hexagonal wurtzite phase with a preferential c-axis orientation that improves on increasing growth time. FESEM images demonstrated that the MZO NRs grow with better alignment and greater size for elongated growth durations. The UV photodetection characteristics of MZO NRs were investigated in metal-semiconductor-metal (MSM) planar configurations at room temperature and are found to be greatly dependent on growth time. The photocurrent increases with an increase in the growth time due to improvement in film crystallinity and mean surface area of nanorods. Both the photocurrent and responsivity were further measured with the variation of optical power density and applied voltage, respectively. Exceedingly stable and fast switching UV photoresponse is seen for the photodetector having MZO NRs arrays grown for 60 min, which shows highest responsivity of 22.33 mA/W upon 2 mW/cm(2) UV illumination (365 nm) at 5 V applied bias. (C) 2015 Elsevier B.V. All rights reserved.