Transmission electron microscope investigation of dislocation loops in Si-doped GaAs crystals

Abstract

Dislocation loops in Si-doped GaAs crystals have been studied by conventional transmission electron microscopy (CTEM) and high-resolution transmission electron microscopy (HRTEM). In addition to the prismatic dislocation loops lying on (110) planes and the faulted loops lying on (111) planes, the existence of prismatic dislocation loops lying on (111) planes with 1/2 (110) Burgers vectors and of interstitial character was identified for the first time. Some of the dislocation loops exhibited partly faulted and partly prismatic characteristics. This observation indicates that the prismatic dislocation loops lying on (111) planes may be converted from faulted loops by the generation and movement of two 1/6 (112) Shockley partial dislocations across the stacking fault. Because all the dislocation loops studied by HRTEM have an extra plane, it was concluded that interstitials are responsible for the formation of dislocation loops.