Dislocation configurations in semi-insulating, n-type and p-type GaAs deformed at 150°C

Abstract

The glide of well defined dislocations in semi-insulating, n-type and p-type GaAs deformed at low temperatures under a high stress has been studied by means of transmission electron microscopy. The shape of the dislocation loop is used as a means to identify the dependence of the dislocation velocity on the doping and to examine the difference in the mobility of 60° segments of the same polarity. In n-type and semi-insulating material there is a strong preference for the dislocations to lie along directions, namely the Peierls valley. In p-type material, segments can also be oriented precisely at the edge orientation. In all materials, non-screw segments often rotate towards the edge orientation by relaxation from the high-stress configuration. Such observations are interpreted in terms of the difference in velocities of the screw kinks and 60° kinks. Weak-beam microscopy of widely dissociated dislocation segments suggests that, even at these low temperatures, there is a strong interaction between point defects and the core of individual partial dislocations.