The role of annealing ambient on diffusion of implanted Si in β-Ga2O3

The most common n-type dopant, Si, was implanted into bulk (-201) beta-Ga2O3 at total doses from 2x10(13)-2x10(15) cm(-2) and annealed at 1100 degrees C for 10-120 secs in either O-2 or N-2 ambients. Secondary Ion Mass Spectrometry profiling showed a significant effect of the annealing ambient on the Si diffusivity. In the case of O-2 annealing, there was extensive redistribution of the Si across the entire dose range, while in sharp contrast, the use of N-2 annealing suppressed the Si diffusion. The results are consistent with a defect-assisted process. Excellent fits to the Si profiles were obtained with the FLOOPS simulator, assuming mobile vacancy/defect concentrations as the important factor for the difference in the O-2 vs N-2 annealing ambients. One possibility is that for N-2 anneals, more Ga vacancies are created, enabling interstitial Si to migrate onto a substitutional Ga site where it has low diffusivity. The N-2 ambient also suppresses loss of Si to the surface, with >90% of the initial dose retained after annealing at 1100 degrees C for 120 secs, compared to 66-77% with O-2 anneals under the same conditions. (C) 2019 Author(s).