Characteristics of Partially Disordered Gallium Nitride Nanodots Synthesized by Pulsed-Laser Ablation

GaN nanodots were synthesized at room temperature in an Ar atmosphere by a laser ablation technique under a pressure of 100 Pa. The synthesized nanodots were found to be smaller than 10 nm and the GaN phase was Ga-rich. High-resolution transmission electron microscopy and its Fourier transform confirmed that these GaN nanodots contained partially disordered crystallites. In spite of this structural instability, their medium ranged atomic order resulted in quantum-shifted luminescence due to the confinement of electrons in the photoluminescence spectra, which is consistent with theoretical calculations on the size-dependent band gap of crystalline GaN.