Asymmetry of anion and cation vacancy migration enthalpies in III-V compound semiconductors: Role of the kinetic energy

In separate publications we have, from a variety of considerations, identified the activation enthalpies for migration by nearest-neighbor hopping, Δ$H_m$, of vacancies in InP as Δ$H_m$(${\mathrm{V}}_{\mathrm{In})}$=0.3 eV and Δ$H_m$(${\mathrm{V}}_{\mathrm{P})}$=1.2 eV. These are in the ratio of the masses of the P and In atoms that actually move when ${\mathrm{V}}_{\mathrm{In}}$’s and ${\mathrm{V}}_{\mathrm{P}}$’s hop to nearest-neighbor sites. Here we argue that this is evidence for the validity of the kinetic interpretation of Δ$H_m$ and the ballistic model of vacancy migration. Indeed, the empirical values are in quantitative agreement with the predictions of the ballistic model. Excellent agreement is also found for ${\mathrm{V}}_{\mathrm{Mg}}$ migration in MgO. We extrapolate this result to predict that high-temperature values for interstitial migration in Si and other tetrahedral semiconductors will also be dominated by a kinetic-energy term and far larger than low-temperature values are known to be.