Optical sensors based on metal oxide nanowires for UV/IR detection

Metal oxide nanowires (NWs) present high stability and excellent optical, electrical and mechanical properties. Their synthesis is cost-effective since they can be produced by means of conventional ovens using vapor phase transport or direct metal oxidation. In this work, n-type ZnO and p-type CuO NWs are deposited on pre-patterned electrodes of Aldoped ZnO (AZO) by dielectrophoresis. Performance of devices fabricated from single and multiple NWs are compared. Highly selective UV detection is demonstrated in n-type ZnO NW photoconductors with high external gains in the 0.09-1$108 range and slow time responses, both effects induced by surface effects. In contrast, n-p-n AZO/ CuO NW/AZO heterostructures show lower gains but faster optical responses, mainly limited by device parasitics. Given the CuO bandgap (1.2 eV), the results are quite promising for the development of hybrid metal oxide detection structures in imaging and photovoltaic applications.