Fabrication of low cost UV photo detector using ZnO nanorods grown onto nylon substrate

Abstract

A novel “ultra thin—high flexible—low cost” nylon was used as a substrate to grow vertically well-aligned ZnO nanorods by hydrothermal method at 85 °C for 4.5 h. This nylon is commercially called “roasting bags” or “oven bags” where anyone can find easily in the market. Pre-heat treatment ZnO seeds/substrate at 180 °C with varying the duration (0.5–6 h) shows important changes. Morphological observations (FESEM, TEM, AFM) reveal the formation of aligned hexagonal-like shaped nanorods where the diameter and length (aspect ratio), surface area as well as the density increase with increasing heat treatment time. XRD analysis confirms the formation of wurtzite ZnO phase with a preferred orientation along (002) direction and enhanced crystallinity. Raman spectroscopy analysis confirms the formation of wurtzite structure with high crystallinity and less defects. The optical band gap estimated from absorbance increases slightly within the range 3.266–3.288 eV. According to the above results, it was found that the optimum heat-treatment temperature and duration to produce uniform ZnO seeds was 180 °C for 3 h. Metal–semiconductor–metal UV detectors were fabricated. Due to the high surface-to-volume ratio and high crystalline quality; the optimized film (3 h) showed the highest responsivity and current gain of 0.07066 A/W and 9.15, respectively for UV light at 365 nm under a 5 V bias.