Photoluminescence study of ZnO nanorods epitaxially grown on sapphire (1120) substrates

Abstract

ZnO nanorods were synthesized on sapphire (112̄0) substrates by metalorganic vapor deposition. The rods exhibited better crystalline and optical properties than those of ZnO rods formed on sapphire (0001) substrates. The emission due to biexcitons is persistent up to ∼200 K, indicating potential for applications in biexciton-based nanoscale short-wavelength light-emitting photonic devices. The exciton–biexciton energy separation is independent of sample temperature. The band edge emission peak at room temperature is a mixture of free exciton and impurity-related transitions.