Direct observation of an enhanced concentration of the principal deep level EL2 at single dislocations

Abstract
Regions of low dislocation density (∼5×102 cm2) in 2‐mm‐thick {001} wafers from indium doped, liquid encapsulated Czochralski grown, 2‐in‐diam. GaAs ingots have been examined by transmission infrared microscopy. Discrete dislocations were located and identified by their etching behavior in the calibrated A/B etchant. Comparison of identical regions before and after etching showed that increased absorption at 1 μm occurred at the sites of each dislocation. The results demonstrate directly that enhancement of [EL2], the concentration of the deep donor level EL2, occurs at single dislocations.