Growth and characterization of ZnO/MgZnO thin film hetero structures on p-Si for visible light detectors

Abstract

ZnO- and MgZnO-based single- and double-layer heterostructures have been grown using an electron-beam evaporation system. Structural, morphological, optical and electrical characteristics were elaborated for all the configurations. Using x-ray diffraction, it was inferred that a hexagonal wurtzite structure is maintained for both ZnO and MgZnO with fairly good crystallinity. Field emission scanning electron microscopy (FESEM) images showed the homogeneous distribution of particles in ZnO and MgZnO throughout the films. Both atomic force microscopy and FESEM images exhibit a larger size for ZnO particles. The UV emission for ZnO at ∼371 nm and MgZnO at ∼359 nm was anticipated from photoluminescence spectra. The visible photoconductive properties of all the different configurations were studied in the dark and under the illumination of a white light source. The highest responsivities measured for the ZnO/MgZnO/Si structure were 0.242 A W−1 and 0.164 A W−1 for as deposited and annealed at 400 °C, respectively. These results show the suitability of bilayer photo detectors for visible light detection.