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) β-Ga₂O₃ at total doses from 2x10¹³-2x10¹⁵ cm^-2 and annealed at 1100 °C for 10-120 secs in either O₂ or N₂ ambients. Secondary Ion Mass Spectrometry profiling showed a significant effect of the annealing ambient on the Si diffusivity. In the case of O₂ annealing, there was extensive redistribution of the Si across the entire dose range, while in sharp contrast, the use of N₂ 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 O₂ vs N₂ annealing ambients. One possibility is that for N₂ anneals, more Ga vacancies are created, enabling interstitial Si to migrate onto a substitutional Ga site where it has low diffusivity. The N₂ ambient also suppresses loss of Si to the surface, with >90% of the initial dose retained after annealing at 1100 °C for 120 secs, compared to 66-77% with O₂ anneals under the same conditions. [ABSTRACT FROM AUTHOR]