J. Phys. III France
Volume 7, Numéro 12, December 1997
Page(s) 2339 - 2360
DOI: 10.1051/jp3:1997263
J. Phys. III France 7 (1997) 2339-2360

Analysis of Large Impurity Atmospheres at Dislocations and Associated Point Defect Reactions in Differently n-Doped GaAs Crystals

C. Frigeri1, J.L. Weyher2, J. Jiménez3 and P. Martín3

1  CNR-MASPEC Institute, via Chiavari 18/A, 43100 Parma, Italy
2  Fraunhofer-IAF, Tullastrasse 72, 79108 Freiburg, Germany
3  Universidad de Valladolid, Departamento de Física de la Materia Condensada, ETS Ingenieros Industriales, 47011 Valladolid, Spain

(Received 2 December 1996, accepted 21 August 1997)

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.

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