Positron lifetime spectroscopy was used to investigate the electric-field distribution which occurred at a Au/GaAs interface. Positrons which were implanted from a 22Na source, and drifted back to the interface, were detected by their characteristic lifetime at interface traps. The relative intensity of this fraction of interface-trapped positrons revealed that the field strength in the depletion region saturated at applied biases above 50V. This observation could not be reconciled with a simple depletion approximation model. On the other hand, the data were fully consistent with a theoretical model for an enhanced EL2+ electron-capture cross-section; above a critical electric field.

Electric-field distribution in Au semi-insulating GaAs contact C.C.Ling, Y.F.Shek, A.P.Huang, S.Fung, C.D.Beling: Physical Review B, 1999, 59[8], 5751-8