Zinc oxide single-crystal microtubes

Abstract

ZnO single-crystal microtubes were fabricated using an encapsulated microwave growth method. The ZnO crystals are grown in hexagonal hollow tube form with a well faceted end and side surfaces, which have cross-sectional dimensions of 100to250μm, lengths of 3–5mm, and wall thickness of 1–2μm. Under optical excitation, a strong near-band-edge emission was obtained at a peak wavelength of 377.8nm with a full width at half maximum of 11nm. The ZnO microtubes exhibited a highly selective UV light response with a cut-off wavelength at ∼370nm, and excellent electron field emission properties with an emission current density of 11mA∕cm2 at an applied field of ∼20V∕μm.