Self-Limiting Growth of GaN at Low Temperatures

GaN thin films were deposited in a self-limiting fashion at low temperatures. Films were deposited on Si substrates by plasma-enhanced atomic layer deposition using trimethylgallium (TMG) or triethylgallium (TEG) as the group-III, and ammonia $(NH_3)$ as the group-V precursors. TMG and TEG saturations were observed at 185 and 150°C, for doses starting from 0.015 and 1 s, respectively. Constant deposition rates of ≈ 0.51 and ≈ 0.48 Å/cycle were obtained within the temperature ranges of 250-350 and 150-350C for TMG- and TEG-based plasma-enhanced atomic layer deposition processes. Oxygen contents of the films were high ( ≈ 20 at.%) as determined by X-ray photoelectron spectroscopy.