Variations in the impurity composition and microhardness of surface layers in silicon crystals caused by a magnetic fiel
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Variations in the Impurity Composition and Microhardness of Surface Layers in Silicon Crystals Caused by a Magnetic Field V. A. Makara, M. A. Vasiliev, L. P. Steblenko, O. V. Koplak, A. N. Kurilyuk, Yu. L. Kobzar’, and S. N. Naumenko Shevchenko National University, Kiev, 03022 Ukraine Submitted June 18, 2007; accepted for publication October 12, 2007
Abstract—Variations in microhardness and impurity composition of surface layers in silicon crystals caused by a magnetic field are observed. It is assumed that the mechanism of slow structural relaxation in silicon crystals is related to an increase in the adsorption function of silicon as a result of the effect of a magnetic field; this mechanism underlies the magnetomechanical effect (the effect of variation in microhardness). PACS numbers: 68.35.Dv, 68.35.Gy, 75.80.+q DOI: 10.1134/S106378260809008X
1. INTRODUCTION The data reported in available publications [1–5] and also our previous studies [6–10] showed that magnetosensitivity effects that manifest themselves in nonmagnetic crystals, including the magnetoplastic effect (a variation in mobility of dislocations under the influence of a magnetic field) and a magnetomechanical effect that consists in a magnetic-field-induced variation in microhardness are not observed in high-quality crystals where there are no dissolved impurity atoms. Golovin [5] noted that the majority of researchers attribute the relation between the influence of a magnetic field on crystals and appearance of magnetosensitivity effects in them exactly to the presence of impurities. In order to gain insight into magnetosensitivity effects, it is necessary to identify the mechanism of modification of defect–impurity subsystem in crystals (this mechanism is caused by the effect of a magnetic field). According to some models [2], the totality of systematic physical features characterizing the magnetodependent effects in nonmagnetic crystals can be explained in the terms of the concept of spin-dependent electron transitions during and after exposure to a magnetic field. As noted in [2, 5], a spin-dependent transition brings about a significant variation in the spin configuration in nanoclusters of structural defects. It is assumed that a magnetic field gives rise to evolution of the spin subsystem in nanoclusters formed by complexes of point defects and by interacting pairs of dislocation–(paramagnetic center), impurity–defect, and so on; this evolution ends with relief of spin-related prohibition for a certain spin-involved transition. Evidently, in order to gain insight into the physical nature of magnetodependent effects in nonmagnetic crystals, it is important to have information about the set of impurities that are present in the crystal (including also paramagnetic impurities).
In connection with the above, the aim of this study was to determine variations in the impurity composition in silicon crystals induced by a low dc magnetic field and special features of the magnetomechanical effect caused by
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