Enhanced Ultraviolet Emission from Hydrothermally Grown ZnO Nano-Grass on Si Substrate

Highly crystalline one-dimensional zinc oxide (ZnO) nano-grass was grown on silicon (Si) substrate by a modified hydrothermal method. A predominantly c-oriented ZnO nano-grass with an average diameter of 40-60 nm and length of 1.5-2.0 mu m was obtained. From the photoluminescence (PL) measurement, we observed a defect-free, intense ultraviolet emission of as-grown ZnO nano-grass, confirming the absence of singly ionized oxygen vacancies. The absence of green deep-level emission in the PL spectrum further implies a high crystallinity of as-grown ZnO nano-grass. The high-quality ZnO nano-grass has potential applications in single nanowire-based light-emitting diodes, solar cells, themoresistive sensing, photocatalysis, ultraviolet photodetectors, optical switches, waveguides and nano-lasers.