High resolution electron microscopic investigations of dislocations in deformed GaAs single crystals doped with Te

Abstract

The defect structure of GaAs single crystals doped with tellurium to about 1019 cm−3 and deformed at 500 °C is investigated in the high‐resolution electron microscope using three‐beam dark‐field lattice images along 〈110〉. The images of precipitates at different stages of their formation as well as of dissociated 60° dislocations, dipoles, and stacking fault tetrahedra are taken and analyzed. The succession of the precipitation stages in the tellurium‐bearing phase is analyzed, too. There are discrepancies between the periodicity on direct lattice images and the interplanar distances in highly deformed regions in the crystal.

Dislocation multiplication in GaAs : inhibition by doping

“…However, the concentration was below the threshold, which does not allow to conclude. Results for Te doping [66,67] seem to support our explanation. 6.…”

“…examination of a 60° dislocations, in heavily Te doped GaAs, does not seem to reveal any change in S.F.E. [67] although the published micrograph corresponds to a S.F.E. of 36 mJ.m-2, slightly smaller than the one for undoped GaAs.…”

“…The effect is particularly efficient at high temperature. This provides an explanation for the increase of dissociation width observed in Te doped GaAs [66,67] and in In doped [60], as well as for the large stacking faults in n-type GaAs, as grown and after annealing [23]. In all these instances, impurities would have segregated in the stacking faults. This observation suggests a very attractive explanation for a whole set of experimental facts in high temperature dislocation behaviour in GaAs.…”

Influence of indium on the dissociation of dislocations in GaAs at high temperature

“…There has been a number of transmission electron microscopy (TEM) studies on the microstructure of deformed GaAs [7][8][9][10][11] including some atomic resolution observations [12][13][14]. Only our previous work [11] gave some results on indium doped GaAs, which contained a level of dopants lower than in the present study.…”

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

“…It must be recalled here that the defects involved in this study are growth defects and not purely stress-induced ones. In addition, the high concentration of In may induce the formation of particular defects, as happens in Te-doped GaAs where condensation of Te along {111} planes induces complex stacking faults (Maksimov, Ziegler, Khodos, Snighiryova & Shikhsaidov, 1984). Finally, it must be pointed out that Burgers vectors along (111) have already been observed within grain boundaries in Czochralski-grown Si (Bourret, Desseaux-Thibault & Lancon, 1983).…”