Enhanced photosensing by Mg-doped ZnO hexagonal rods via a feasible chemical route

Abstract

One-Dimensional (1D) pure-ZnO, Zn0.9Mg0.1O and Zn0.8Mg0.2O thin films have been successfully grown over a glass substrate using simple economical chemical bath deposition method (CBD). This investigation explores the enhancement in photocurrent and photosensitivity of Zn1−xMgxO thin films via induced defects with vertically aligned hexagonal rod-like array thin films. The structural, optical and electrical properties of the synthesized materials have been elucidated using X-ray Diffraction (XRD), Raman, UV–Vis spectroscopy, Photoluminescence (PL), and I–V characteristics. Hexagonal rod-like morphology has been confirmed from both XRD and SEM results. Change in structural properties revealed that the formation of the Mg(OH)2 phase for Zn1−xMgxO thin films from XRD spectra. Thus, the impact of extra Magnesium (Mg) which is difficult to incorporate in ZnO lattice sites which causes the phase segregation and possibly creates morphological and structural defects. This has been also confirmed from electron–phonon interaction in Raman analysis. Such as the Raman-shift of E2 (high) mode in Zn1−xMgxO thin films towards higher frequencies indicates the substitution of Mg at O lattice sites. However the formation of phase segregation had a significant effect on optical as well as electrical properties of the ZnO hexagonal rods thin films. From UV–Vis spectra, the intensity of absorption edges for Mg-doped samples are decreases while the optical band gaps are increases from 2.87 to 3.47 eV and also from PL spectrum shows that the defect states in visible range are increases with increasing Mg content in ZnO. The parameters like photocurrent and electrical resistance are calculated from I–V characteristics and the results shows that the photosensitivity enhanced as Mg content increases in ZnO.