It was recalled that knowledge of the positron affinity was important in understanding positron trapping at interfaces and precipitates. Theoretical calculations of the affinity were made for the 3C, 4H and 6H polytypes on the basis of various approaches to electron-positron correlations within the local-density approximation. The generalized gradient approximation for positrons was compared with experimental data on work functions. A disagreement between theoretical and experimental values of the affinity was explained in terms of the difficulty of making precise measurements of the positron work function.

Positron affinity in semiconductors J.Kuriplach, M.Sob, G.Brauer, W.Anwand, E.M.Nicht, P.G.Coleman, N.Wagner: Physical Review B, 1999, 59[3], 1948-55