Analysis of large impurity atmospheres at dislocations and associated point defect reactions in differently n-doped GaAs crystals

The large impurity atmospheres at dislocations typical of n-type (Si- or Te-doped) CaAs crystals have been analysed by localized measurements of the free electron concentration, diffusion length and DSL etching velocity. The atmospheres always contain dopant atoms as well as point defects (complexes) whose formation and type depend on the type of dopant impurity and melt stoichiometry. The donor- or acceptor-like characteristics of such point defects (complexes) are responsible for the observed remarkable difference in the electrical and recombinative properties of the atmospheres between the differently doped crystals. The point defect reactions at the base of the formation of the slip traces are discussed. The possible mechanisms of the impurity-dislocation interaction leading to the formation of the atmospheres are also considered