Positron experiments in δ-doped GaAs(Si) superlattices: Defect properties and positron diffusion

The slow positron beam and the positron diffusion analysis were used to investigate the annihilation fractions of different layers in Si δ-doped GaAs superlattice. In the analysis we studied the influence of the shape and the strength of an electric field between the delta planes on the positron diffusion. The results indicate that the Si δ-doped planes are totally repulsive to positrons. The defects in a superlattice structure observed by the positron are thus located in undoped material between the delta planes.