Ga2O3 nanoparticles synthesized in a low-pressure flame reactor

Ga2O3 was-synthesized by doping a premixed H2/O2/Ar flat flame with diluted trimethyl gallium Ga(CH3)3 in a low-pressure reactor. The mean particle diameter d p of the resulting metal oxide was characterized in-situ with a particle mass spectrometer (PMS), and was observed to range between 2.5 nm ≤ d p ≤ 6.5 nm. XRD results show that the as-synthesized Ga2O3 nanoparticles are mostly amorphous, although, a few broad reflexes were observed that indicate the presence of some degree of crystallinity. Thermal annealing of the as-synthesized material at 1000 °C for 5 min yielded β-Ga2O3 with a monoclinic structure. UV–VIS measurements indicate strong absorption in the UV range (4.8 eV), which corresponds quite well to the direct band gap of bulk Ga2O3. Photoluminescence (PL) measurements of the as-synthesized metal oxide show a broad emission ranging from 350 nm to 600 nm with a maximum at 460 nm. Crystalline β-Ga2O3 exhibited stronger luminescence than as-synthesized particles.