A Spectrum Image Cathodoluminescence Study of Dislocations in Si-Doped Liquid-Encapsulated Czochralski GaAs Crystals

Dislocations in Si-doped liquid-encapsulated Czochralski GaAs crystals have been studied by spectrum imaging cathodoluminescence. The interaction between the dislocations and the crystal matrix results in complex atmospheres, which can extend several tens of micrometers around the dislocations. The formation of these atmospheres depends on the melt stoichiometry and the doping level. Different atmospheres formed during growth and postgrowth cooling were studied. Their main characteristics and possible scenarios of formation are suggested, taking account of the characteristics of the samples in terms of [As]/[Ga] ratio and doping. Excess As defects seem to play a major role in the formation of the atmospheres.