Controlled Formation of β-Si3N4 on Native Oxidized Silicon Wafers in Ammonia Flow

The formation of β-Si3N4 for subsequent growth of AlGaN and GaN heterostructures of silicon wafers has been studied. It is established that the native oxide layer protects the silicon surface from the formation of amorphous silicon nitride when heating in an ammonia flow. Controlled formation of β-Si3N4 at partial ammonia pressures up to 3 × 10–5 Torr is demonstrated. This circumstance makes it possible to perform epitaxy of nitride films without cleaning the growth chamber from ammonia, which is usually required to remove the native silicon oxide by high-vacuum annealing.