Low-temperature growth of GaN by atomic nitrogen based on a dielectric barrier discharge

GaN films were deposited on sapphire(0001) and Si(100) substrates by MOCVD using an atomic nitrogen source based on a dielectric barrier discharge (DBD) method. Molecule nitrogen and trimethylgallium (TMG) were separately delivered to the substrates. Wurtzite GaN films, with no trace of cubic GaN, were successfully growth on α-Al₂O₃ substrates even at relatively low temperatures (<800°C). Sapphire substrate RMS roughness was 5.01 and 4.93 angstrom before and after the exposure to DBD N-source, respectively. This shows negligible irradiation damage of accelerated N₂ ⁺ ion as well as the effect of smoothening the substrate surfaces with DBD N-source. The PL results exhibited small luminescence at the spectral region of blue and UV but a luminescence around the yellow region (2.5 eV) was detected. This is caused by oxygen impurity from AES analysis.