Lifetime Spectra of Positrons in GaAs Deformed by Ga- and As-Bending

Positron lifetime measurements have been performed in plastically bent n -type GaAs single crystals in which either Ga- or As-dislocations were introduced. τ 1 and I 1 were decreased by deformation, while I 2 was increased. Following the trapping model, the trapping rates were deduced experimentally, which in turn gave the cross widths of the Ga- and As-dislocations as 2.2×10 2 Å and 2.9×10 2 Å, respectively. In terms of Read's model for the electric charge of the dislocation in semiconductors, the fractions of the dangling bonds occupied by electrons for the Ga- and As-dislocation were obtained as 0.65 and 0.75, respectively.