Stacking-Faults in Tellurium-Doped Gallium Arsenide

Samples of bulk-grown gallium arsenide single crystals, taken from both static freeze, and Czochralski ingots doped to a high level with tellurium, have been examined using transmission electron microscopy. Observation of single and multiple stacking-fault layers which have fault vectors of the kind R = a/3 < 111 > is reported. It is shown by diffraction contrast experiments that the stacking-fault defects are extrinsic. They are thought to be rafts of tellurium substituting for arsenic in {1 1 1} planes. The prevalence of the observed layer defects correlates well with the increase in carrier concentration in certain regions of the crystals.