Synthesis of nanocrystalline GaN by the sol-gel method

Single-phase wurtzite GaN nanocrystals with an average diameter of 11.2 nm were synthesized through a sol-gel technique and subsequent nitridation. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) confirmed they had a hexagonal structure and a narrow size distribution of the nanocrystals. X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) measurement showed that the GaN powder was of single-phase wurtzite structure with a considerable fraction of structural defects such as twin and stacking faults. The IR spectrum showed that only the Ga-N stretch is present at 580cm^-1. Room-temperature photoluminescence measurement revealed a broad emission ranging from 2. 6 to 3. 2 eV with some fine structures, which are believed to be associated with the defect levels.