Diffusion of dopants and impurities in β-Ga2O3.

The understanding and availability of quantitative measurements of the diffusion of dopants and impurities in Ga₂O₃ are currently at an early stage. In this work, we summarize what is known about the diffusivity of the common donor dopants, Sn, Ge, and Si, as well as some of the deep acceptors, N, Fe, and Mg, and donors, Ir. Two commonly encountered interstitial impurities are H and F, the former through growth and processing ambients and the latter through its use in plasmas used for stripping dielectrics from Ga₂O₃. Both are found to have high diffusion coefficients and an effect on electrical conductivity, and H shows anisotropy in its diffusion behavior. Si, Ge, and Sn implanted into bulk β-Ga₂O₃ at total doses from 2 × 10¹³ to 2 × 10¹⁵ cm⁻² and annealed at 1100 °C for 10–120 s in either O₂ or N₂ ambients showed a significant effect of the annealing ambient on the donor's diffusivity. In the case of O₂ annealing, there was extensive redistribution of the Si, Sn, and Ge across the entire dose range, while, in sharp contrast, the use of N₂ annealing suppressed this diffusion. The N₂ ambient also suppressed loss of dopants to the surface, with >90% of the initial dose retained after annealing at 1100 °C for 120 s, compared to 66%–77% with O₂ anneals under the same conditions. [ABSTRACT FROM AUTHOR]