AUGER INVESTIGATION OF GROUP-III NITRIDE FILMS GROWN BY MOLECULAR-BEAM EPITAXY

We discuss the growth and properties of III-nitride films prepared by molecular beam epitaxy (MBE) using an RF activated nitrogen plasma source. Binary compounds of GaN and InN have been grown on (001) oriented GaAs substrates at 0.2 to 0.4 mu m/h. A novel material system Ga(AsN), which can in principle be lattice matched to GaP (or Si), has been studied. Alloy films of In(AsN) have also been prepared. The properties of the films were investigated using in-situ reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). We have established that GaN and InN films grown at 620 and 300 degrees C, respectively, can be prepared with relatively abrupt epilayer-substrate interfaces. However, InN grown at a higher substrate temperature (similar to 350 degrees C) has a much less abrupt interface. The nitrogen content of the alloy films of Ga(AsN) is estimated to be approximately 20% from AES studies. Oxygen, commonly observed in AES studies of nitrides, is present on the film surface and arises from rapid oxidation due to residual gases in the analysis chamber and/or from the argon used for sputtering. However, oxygen is not detected in AES sputtering studies and is therefore not present in the bulk of the films within our detection limit (similar to 0.1%).