Preferential precipitation on dislocation loops in Te-doped gallium arsenide

Abstract

Heat-treated tellurium-doped gallium arsenide contains prismatic and faulted dislocation loops with precipitate particles lying on the dislocation core. The position of the precipitates on the loops has been studied revealing preferential precipitation on 〈110〉 line segments for both faulted and prismatic loops. From a consideration of the atomic arrangements at the dislocation cores it is concluded that the precipitates preferentially decorate the prismatic loops where the dislocation core is identical to either a β_ss or α_gs Lomer dislocation. Precipitates on the {111} faulted loops, however, can appear on all possible 〈110〉 dislocation segments. The faulted loops are thought to consist of a layer of gallium telluride, and, since this is a defect lattice containing gallium vacancies, β type dislocation core structures can occur along all six 〈110〉 directions. By analogy with the faulted loops, preferential precipitation on prismatic loops is believed to occur on β_ss Lomer dislocations.