Published online by Cambridge University Press: 28 February 2011
2" diameter wafers cut from indium doped, liquid encapsulated Czochralski (LEC) grown GaAs ingots have been examined by two different methods. Dislocations were revealed by etching, and isolated regions of enhanced [EL2], the concentration of the deep donor level EL2, weredetected by infrared transmission microscopy. In regions of low dislocation density (∼5 × 102 cm−2) single isolated dislocations were identified and at the identical sites infra-red micrographs showed increased absorption. The results demonstrate that enhancement of [EL2]occurs at single dislocations, and that the enhancement can be detected by suitable etching techniques.