Microdefects in Si-doped HB GaAs crystals investigated by TEM, DSL photoetching and laser scattering tomography

Microdefects giving rise to high microroughness after DSL photoetching in Si-doped GaAs crystals have been studied by TEM. They turned out to be small dislocation loops which sometimes were also decorated by particles. The smallest loops were faulted and of the 1/3 <111> type, whereas the largest ones were of the 1/2 <110> type. Such microloops are at the origin of the surface microroughness after DSL as they produce small etch hillocks. The origin of the microloops is also discussed.