Plasma-Enhanced Atomic Layer Deposition of III-Nitride Thin Films

AlN and GaN thin films were deposited by plasma-enhanced atomic layer deposition using trimethylmetal precursors. The films were found to have high oxygen incorporation, which was attributed to oxygen contamination related to the plasma system. The choice of nitrogen containing plasma gas (N-2, N-2/H-2 or NH3) determined the severity of oxygen incorporation into deposited films. Lowest oxygen concentrations were attained for AlN and GaN thin films using NH3 and N-2 plasma, respectively. Initial experiments have shown that GaN thin films with low impurity concentrations can be deposited when plasma-related oxygen contamination is avoided by the use of an alternative plasma source.