Annealing temperature-dependent morphology, structure, and optical properties of well-aligned ZnO nanowire arrays

Abstract

In this paper, using a facile and low-cost chemical bath deposition route, well-aligned zinc oxide (ZnO) nanowire arrays (ZNWAs) were grown on the silica glass substrate at low temperature. The as-grown ZNWAs were then annealed at different temperatures from 400 to 800 °C, their morphology, crystalline structure and optical properties were analyzed in detail. The results showed that both the average diameter and length of ZnO nanowires increased with raising annealing temperature, when annealing temperature was 600 °C, the ZnO nanowires had the best crystallization quality and minimum Urbach energy, near band edge (NBE) emission peak increased sharply. In addition, when the annealing temperature was up to 800 °C, many adjacent ZnO nanowires bonded together in the ZNWAs, a substantial increase of their lattice disorder induced by too high annealing temperature, a sharp decrease in optical transmission of the ZNWAs in the visible region was found, their Urbach energy increased dramatically and crystallization quality became poor.