REDUCTION OF THREADING DISLOCATION DENSITIES IN HEAVILY LATTICE-MISMATCHED PBSE ON SI(111) BY GLIDE

Epitaxial PbSe layers on Si(111) relax nearly completely owing to the easy dislocation glide in the main {100}[110] glide system. Threading dislocations introduced by the thermal mismatch strains are able to mo ve distances of several cm and to escape at the edges of the samples. Etch-pit densities as low as 10(6) cm(-2) were obtained in layers with a thickness of d = 4 mu m. The etch-pit density scales with 1/d(2), w hich may be understood as a consequence of the annealing step and of t he high mobility of dislocations. By applying several anneal cycles, t hreading dislocation densities of essentially zero should result.