Critical role of dopant bond strength in enhancing the conductivity of n-type doped κ-Ga2O3

We report a density functional theory study on the effects of n-type doping on the electrical conductivity of κ-Ga2O3. Both group-IV (X = Si, Ge, Sn) and group-VII dopants (Y = F, Cl, Br, I) are considered. All dopants introduce resonant donor states above the conduction band minimum, which induce a semiconductor-to-metal transformation. The resonant donor states interact with the extended conduction band-edge via a charge transfer mechanism, altering the band-edge effective mass me* and electron mobility μe. me* exhibits a linear dependence on the strength of X-O (Ga-Y) bonds, making the latter a good descriptor for quantifying the effect of dopants. Using this descriptor, we predict that dopant C may provide a higher conductivity under O-rich condition.