Gas phase studies of trimethylgallium with ammonia, propylamine and water at elevated temperatures: Towards an understanding of GaN growth and oxygenincorporation

The reactions between trimethylgallium (TMG) and three reactants were studi ed to provide some insight into the reaction mechanism of gallium nitride g rowth and oxygen incorporation. All reactions were studied in a flow reacto r. The gas phase was analyzed by molecular beam sampling mass spectrometry. Ammonia is a widely used precursor for the deposition of GaN films. Ln the gas phase, different gallium- and nitrogen-containing species were detecte d as a function of temperature. Propylamine is:pyrolyzed at lower temperatu res than ammonia and could therefore provide a low-temperature route toward s GaN. In the reaction of TMG with propylamine, a different behavior was fo und; only simple adducts with one gallium atom per molecule were detected, which were instable at higher temperatures. The reaction of TMG with water is an important side reaction: because water is the main impurity of ammoni a and could thus be the main reason for the high oxygen levels found in GaN films.