Quasiparticle Corrections to the Electronic Properties of Anion Vacancies at GaAs(110) and InP(110)

We propose a new method for calculating optical defect levels and thermodynamic charge-transition levels of point defects in semiconductors, which includes quasiparticle corrections to the Kohn-Sham eigenvalues of density-functional theory. Its applicability is demonstrated for anion vacancies at the (110) surfaces of III–V semiconductors. We find the ($+/0$) charge-transition level to be 0.49 eV above the surface valence-band maximum for GaAs(110) and 0.82 eV for InP(110). The results show a clear improvement over the local-density approximation and agree closely with an experimental analysis.

Figure 1

Position of the optical $1a^{\prime \prime }$ defect level of the anion vacancies at GaAs(110) and InP(110) as a function of the occupation number. The geometry is identical in all calculations for the same material and optimized for the neutral charge state. The Slater-Janak transition-state approach (●) yields the ionization potentials and electron affinities in the LDA. More accurate results are obtained by calculating the quasiparticle corrections within the $G_0{W}_0$ approximation (■). In either case the energy zero is set to the respective surface valence-band maximum.