Dynamic interaction of dislocations with impurity subsystem in crystalline materials
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STRUCTURE OF CRYSTALS Dedicated to the memory of A.V. Shubnikov
Dynamic Interaction of Dislocations with Impurity Subsystem in Crystalline Materials B. V. Petukhov and P. A. Klyuchnik Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow, 119333 Russia email: [email protected] Received May 31, 2011
Abstract—The entrainment of impurities by moving dislocations results in the accumulation of impurities in dislocation cores, which eventually significantly modifies the dynamic properties of dislocations. In the framework of the kink mechanism, the possible modes of motion are found selfconsistently and the condi tions for dislocation immobilization are determined. The dependence of the immobilization stress (the parameter that is most important for “defect engineering” in semiconductors) on the material parameters and experimental conditions is calculated. DOI: 10.1134/S1063774512030169
INTRODUCTION Mechanical and electrical properties of crystalline materials are determined to a great extent by their defect structure, i.e., impurities, clusters, dislocations, etc. The progress in the growth of perfect semiconduc tor crystals has opened up the possibility of indepen dently studying the role of various defects in the deter mination of material properties by modifying original samples. This initiated the development of socalled defect engineering, i.e., the elaboration of methods for obtaining desired properties by the targeted control of the defect structure. At the same time, the interaction of dislocations with impurities in semiconductor materials results in a number of technologically important phenomena whose origin has not been ade quately described. In particular, the possibility of pro ducing a stress range in which the dislocations do not move and do not propagate from the surface sources into the crystal depth is studied, which is important for the growth of dislocationfree semiconductor materi als and the stable operation of microelectronic devices [1–3], etc. The presence of starting stress, which is called the dislocation unlocking stress, in crystals with impurities was found long ago [4]; this stress has been studied under both static [1] and dynamic [5] conditions. In the static mode, the starting stress appears due to the impurity diffusion to dislocations. Its value depends on the exposure time. The analysis of the experimental data for Czochralskigrown silicon containing oxygen impurities showed [1] that the initial stress in the tem perature range 650–850°C has a force nature and is determined by the binding energy of a single oxygen impurity to a dislocation:Eb ≈ 0.74 eV. At lower tem peratures, the binding energy is 0.2 eV, which suggests the decisive influence of species of other types. In this
context, in this paper the “impurity” concept is con sidered in a somewhat generalized sense, including species of other natures as well, e.g., dimers. For dynamic conditions, it was found [5] that the dislocation velocity under lower stress de
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