DISLOCATION REACTION ON P-DOPED GAAS (011) OBSERVED BY SCANNING TUNNELING MICROSCOPY

Scanning tunnelling microscopy (STM) was used to study volume dislocations penetrating the (011) surface of plastically deformed p-type GaAs single crystals. Only dislocations producing a double atomic step at the surface could be observed The dislocation cores were strongly localized on the surface at the end of two inserted rows. This led to considerable lattice distortion around the dislocation core. In contrast to n-type material the observed Burgers vector of p-type GaAs had the form a[110BARBAR], which is twice the length observed for perfect dislocations in the bulk. A possible dislocation reaction at the surface during the cleavage process resulting in the observed surface Burgers vector is discussed. As in n-type material no band bending was seen around the dislocation cores. The observed dislocations showed a tip-induced (voltage-dependent) movement.