Microcavity lasing behavior of oriented hexagonal ZnO nanowhiskers grown by hydrothermal oxidation

The highly aligned ZnO whiskers, which are grown by hydrothermal oxidation of metallic zinc plate in the presence of ethylenediamine molecules, exhibit single and/or a few modes of supernarrow spectral emissions $\text{(∼0.7\hspace{0.17em}}\mathrm{nm})$ at near 378 nm and negligible deep level defects emissions. Time-integrated and time-resolved photoluminescence show that the supernarrow spectral peaks are due to the laser action with an excitation threshold about $\text{70\hspace{0.17em}μ}{\mathrm{J/cm}}^2$ and emission lifetime of $\text{<30\hspace{0.17em}}\mathrm{ps}.$ The lasing emission is highly polarized along the excitation laser polarization direction. The low lasing threshold, stable and regular supernarrow longitudinal modes, and strong lasing polarization effects can be well explained by the model of microcavity laser where the two end facets of whisker form the microcavity.