Characterization of denuded zones around dislocations in doped GaAs by phase contrast microscopy and photoluminescence

Photoluminescence spectroscopy and infrared phase contrast microscopy are used for the investigation of zones around grown-in dislocations in GaAs doped with various group II, III, IV and VI elements. PL-results on Si-and Ge-doped samples indicate that these zones are characterized by a reduced concentration of Si_As and Ge_As-acceptors, respectively. We conclude that, in general, dislocation–surrounding zones in doped GaAs represent areas denuded of As-sublattice impurities. This is confirmed by variations of the free electron concentration near dislocations detected by phase contrast microscopy for various doping elements. Zones around dislocations are only visible in the case of dopants which occupy the As-sublattice. Zn-and Sn–doped GaAs do not show such denuded zones because these elements are incorporated on Ga-sites only.