Fabrication of an ultraviolet photoconductive sensor using novel nanostructured, nanohole-enhanced, aligned aluminium-doped zinc oxide nanorod arrays at low immersion times

Novel nanostructured thin-film arrays of nanohole-enhanced aligned aluminium (Al)-doped zinc oxide (ZnO) nanorods were prepared using sonicated sol-gel and immersion methods for metal-semiconductor-metal (MSM)-type ultraviolet (UV) photoconductive sensor applications. These nanorod arrays were grown on a glass substrate coated with ZnO nanoparticle thin film as a seed layer at immersion times ranging from 10 to 120 min. Notably, the nanoholes appeared on the nanorods after the annealing process due to the evaporation of water and impurities. The photocurrent properties for the Al-doped ZnO nanorod arrays were significantly improved, increasing by more than five-fold compared to the seed layer when the sensor was illuminated with 365 nm UV light at a density of 750 μA/cm2. Interestingly, the highest responsivity using the Al-doped ZnO nanorod arrays was 1350.84 A/W with an improved photocurrent-to-dark current ratio of 22.7, achieved for the samples prepared with a 50 min immersion time and a gap between metal contacts of 0.07 mm. Our results show that high-performance UV photoconductive sensors can be achieved using a novel structure of nanohole-enhanced aligned Al-doped ZnO nanorod arrays prepared at low immersion times which reduces fabrication time and cost.