Wavelength-tunable and high-temperature lasing in ZnMgO nanoneedles

Zn1-xMgxO nanoneedles were prepared by an ion-beam technique on Zn1-xMgxO thin films with Mg contents of up to 21 at. %. The photoluminescence emission energies of the Zn1-xMgxO nanoneedles measured at room temperature increased monotonically with Mg contents and it reached 3.6 eV when x=0.21. Random laser action was observed in the Zn1-xMgxO nanoneedles with x≤0.1 at temperature ranging from 300 to 470 K under 355 nm optical excitation. The characteristic temperature of the Zn1-xMgxO nanoneedles was determined to be 84 K. The high-temperature lasing of the Zn1-xMgxO nanoneedles are attributed to the high crystal quality of the nanoneedles, enhancement of oscillator strength in nanostructures, and a self-compensation mechanism in random laser cavities.