Identification of Burgers vectors along <111> in In-doped GaAs, by X-ray transmission topography and image simulation

Abstract

Long dislocations with Burgers vectors along (111) are unusual in f.c.c, lattices. X-ray topographs have been obtained of as-grown GaAs crystals doped with 1020 atoms cm -3 of In, where the usual extinction criterion g.b = 0 leads to this type of defect. However, for several g satisfying the condition g.b = 0 with b = a [111], the images of these dislocations were still clearly visible.

Dislocation multiplication in GaAs : inhibition by doping

“…In order to explain the mechanism of dislocation density reduction, the characteristics of residual dislocations have been determined in highly doped GaAs, especially for Si and In doping. Various kinds of defects have been found [20] : dislocations emerging from the interface with the seed, glide dislocations, helical dislocations and others with unusual Burgers vectors [21,22]. It can be noted that, for Si or In doped GaAs, there is a relation between the amount of impurities and the shape of dislocations, suggesting that the extent of cross-slip or climb mechanisms depends on the impurity concentration.…”