Damage structure of gallium arsenide irradiated in a high-voltage electron microscope

Abstract

Semi-insulating, undoped gallium arsenide has been irradiated in a high-voltage electron microscope between room temperature and about 500[ddot] C for doses of up to 5 × 10²² electrons cm⁻² at 1 MeV. Room-temperature irradiation produces small (less than 5 nm) damage clusters. As the temperature of the irradiation is increased, the size of these clusters increases, until at about 300[ddot] C a high density of dislocation loops can be resolved. The dislocation loops, 20 nm or less in diameter, which are produced at about 500[ddot] C have been analysed in a bright field using a two-beam inside-outside method which minimises the tilt necessary between micrographs. It is concluded that the loops are an interstitial perfect-edge type with a Burgers vector of (a/2)<110>.