Improving the optical and crystal properties of ZnO nanotubes via a metallic glass quantum dot underlayer

In this study, high density (∼38 μm−2) ZnO nanotubes (NTs) were hydrothermally synthesized on a Cu47.2Zr42.1Al6.7Ti4.0 metallic glass quantum dot (MGQD)/glass substrate. The MGQD acts as a buffer and seed layer to improve the optical and crystalline properties of the ZnO nanotubes. The photocurrent-to-dark current ratio (∼2 × 104) of the ZnO NTs/MGQD is 28.1 times higher than that of ZnO NTs due to the Schottky junction and the localized surface plasmon resonance effect of the MGQD. The photocurrent-to-dark current ratio of the ZnO NTs/MGQD junction was enhanced an additional 10-fold to ∼2.0 × 105 upon annealing at 150 °C for 30 min under ambient atmosphere. The annealing treatment also decreased the photoresponse and relaxation times.