Photoconductive UV detectors based heterostructures of Cd and Mg doped ZnO sol gel thin films

The photoconductive properties of single (CdZnO/MgZnO, Li:CdZnO/MgZnO) and double (MgZnO/ZnO/MgZnO, CdZnO/ZnO/MgZnO) heterostructures were studied by sol gel method at different annealing temperatures. These structures were analysed by X-ray diffraction (XRD) and photoluminescence (PL). The photoconductive measurements were carried out by semiconductor parametric analyzer. The hexagonal wurtzite structure was retained with good crystalline nature. The UV related strong near band edge (NBE) emission, ultra violet and blue green emission peaks were observed from PL spectra. Photocurrent was observed to have enhanced as a result of annealing temperature and Li substitution in the doped ZnO lattice. The increase of responsivity at ten orders of magnitude was found. Meanwhile, the dark current was found to have increased slightly due to the adsorption of O₂ and H₂O molecule on the surface of the film. Sub-linear behaviour of photocurrent was also observed. - Graphical abstract: Display Omitted - Highlights: • Preparation of heterostructures by sol gel method. • Observation of different defect related emission from PL. • Photoconductivity and responsivity is enhanced by Li codoped ZnO:Cd active layer. • Flow of trap limited current inside the device is estimated