Abstract
The quantitative effect of dislocations on the sheet carrier concentration of a Si-implanted and annealed layer in semi-insulating GaAs is investigated microscopically by the van der Pauw method using small Hall chips with a 40×40 µm2 measurement area. Dislocations affect the sheet carrier concentration within about a 75 µm radius area, and the carrier concentration increases 3×1015 cm-3 per dislocation in this area.