Lasing characteristics of ZnO nanostructures with various morphologies

Semiconductor nanostructures are very promising for future photonic devices owing to their unique optical properties which are quite dependent on their morphology. We report lasing characteristics of ZnO nanostructures with various morphologies including nano-wire, nano-taper, porous nano-wires, and nano pencils. Single crystalline ZnO nanostructures are synthesized using chemical vapor transport and condensation (CVTC) or aqueous reaction. Nonlinear optical properties of nanostructures are investigated. Optical pumping of ZnO nanostructures is carried out using micro photoluminescence (u-PL) system with the frequency-tripled output (355nm) of a Nd:YAG laser (repetition rate of 10 Hz and 6 ns pulse width). We observe an enhancement in laser emission intensity as the morphology of the nanowire changes the facet structure to porous structure. The variation of optical properties can be explained in terms of modified emission rate in ZnO nanowires with large surface area.