Tunable ultraviolet sensing performance of Al-modified ZnO nanoparticles

Abstract The potential of polycrystalline Al-doped ZnO nanoparticles as an active material for UV photodetectors has been investigated. The Rietveld refinement of powder X-ray diffraction data revealed a single hexagonal phase of the nanoparticles. A slight deviation in the lattice cell constants from pristine ZnO was observed, associated with defect creation and strain generated due to Al3+ substitution. High-resolution transmission electron microscopy image reveals a spherical morphology of both the doped and undoped ZnO nanoparticles. Stacking faults observed in the Al-doped samples is an indication of a proper Al-doping and is a signature of high density of crystal defects. The bandgap was found to reduce due to the delocalization of impurity energy states as a result of Al3+ substitution. Consequently, conductivity was improved in doped samples. Photoluminescence spectroscopy revealed a strong dependence of the emissions from defect sites on dopant content. Further, a correlation of the FWHM of the E 2 high Raman mode to the Urbach energy was observed. The UV sensing analysis demonstrates the enhancement of the photocurrent and improved sensitivity. Thus, this work provides a simple, cost-effective, and tunable processing strategy for synthesizing and applying ZnO-based nanomaterials for high-performance UV photodetectors.