Fabrication and properties of ZnO nanorods based MSM UV detectors on silicon substrates

This work reports the ultraviolet (UV) detection characteristics of zinc-oxide (ZnO) nanorods (NR's) based metal-semiconductor-metal (MSM) devices. ZnO NR's were grown on silicon (Si) substrates (p-type) by low-temperature hydrothermal method in two steps. In the first step, approximately 50 nm thick pure ZnO seed-layer was grown on Si, then in the second step, main growth of ZnO NR's were done above seed-layer. The structural morphology of ZnO NR's were investigated by atomic force microscope (AFM) and by cross-sectional scanning electron microscopy (X-SEM) respectively. The results showed that high density NR's were grown uniformly above the ZnO seed layer and the tip of NR's were found in the shape of a hexagonal. After the growth of ZnO NR's, interdigited palladium (Pd) electrodes were deposited by using shadow-mask technique. The electrical characterization of the Pd/ZnO-NR's/Pd based detectors was studied under UV light. The values of contrast-ratio and responsivity were calculated from I-V characteristics of MSM UV detectors. These results may be helpful for the simplistic fabrication of hydrothermally grown ZnO NR's based UV detectors.