Nitridation of GaAs surfaces using nitrogen molecules cracked by a hot tungsten filament

We performed the nitridation of (001) GaAs surfaces using nitrogen molecules (N2) cracked by a hot tungsten filament. After nitridation of a GaAs surface at 620°C for 90 min, the [110] RHEED pattern shows the mixed spotty pattern of GaAs and GaN, while the [¯110] RHEED pattern shows a streak pattern with the spacing of a GaAs lattice. The nitridation rate is independent of the substrate temperature below 530°C. Above 590°C, N2 desorbs from the surface during nitridation. This desorption rate of N2 from the nitrided GaAs surface is the smallest among those of column V molecules in InAs, InP, GaAs and GaP, due to the large standard heat of formation for GaN.