Behavior of dislocations in silicon in the presence of mechanical and magnetic perturbations

Various types of dislocation stoppers are identified and their basic parameters are determined. Using dislocation loops as an example, the effect of internal stresses on the motion of linear defects in n-and p-Si in the field of external elastic forces is estimated. It is found that preliminary magnetic treatment of silicon plates activates the dislocation transport. In the absence of external mechanical loads, displacement of dislocation half-loops (30–50 μm) in the nonuniform field of internal stresses in a silicon crystal with a scratch (stress concentrator) is detected experimentally during isothermal annealing for 0.5–3 h at a temperature of 600–700°C. Dislocation transport is described taking into account the intrinsic (lattice) potential barrier of the crystal and two types of stoppers on the basis of magnetosensitive point defects (dopant) and “forest” dislocations. A kinetic model is proposed for describing the magnetostimulated variation of the mobility of linear defects associated with the formation of long-lived complexes with a paramagnetic impurity. It is found experimentally that the velocity of dislocations in n-and p-Si increases by a factor of 2 and 3, respectively, upon treatment of the semiconductor in a magnetic field B=1 T for 5–45 min. The “magnetic memory” effect in silicon containing dislocations is detected and kinetic aspects of the effect under natural conditions of sample storage after the removal of the magnetic field are considered. Partial velocities of dislocations and their delay times at various types of stoppers are calculated from the matching of experiment with theory.     

Dynamics of surface dislocation ensembles in silicon under conditions of mechanical and magnetic perturbations

This paper reports on the results of investigations into the dynamics of surface dislocation ensembles in silicon under conditions of mechanical and magnetic perturbations. The motion of defects is described with due regard for barriers of three types, including magnetically sensitive point defects and dislocations. Within the concept of spin-dependent reactions between structural defects, a kinetic model is proposed for the magnetic-field-stimulated changes observed in the dislocation mobility due to the formation of long-lived complexes involving paramagnetic impurities. It is experimentally proved that the preliminary treatment of dislocation-containing crystals in a magnetic field (B=1 T) for 5–45 min leads to an increase in the velocity of dislocations in n-Si and p-Si samples by factors of two and three, respectively. The magnetic memory effect is observed in dislocation-containing silicon crystals. Consideration is given to the decay kinetics of the magnetic memory during storage of the silicon samples under natural conditions after magnetic treatment. The basic quantitative characteristics of the motion of linear defects in a magnetic field (for example, the partial velocities of dislocations, the dynamics of dislocation segments at stoppers of different types, and the expectation times for the appearance of the appropriate stoppers) are determined by fitting the experimental data to the theoretical results.     

Superconductivity in disordered thin films: giant mesoscopic fluctuations

We discuss the intrinsic inhomogeneities of superconductive properties of uniformly disordered thin films with a large dimensionless conductance g. It is shown that mesoscopic fluctuations, which usually contain a small factor 1/g, are crucially enhanced near the critical conductance g(cF) > 1 where superconductivity is destroyed at T = 0 due to Coulomb suppression of the Cooper attraction. This leads to strong spatial fluctuations of the local transition temperature and thus to the percolative nature of the thermal superconductive transition.     

Theorems concerning the uniqueness of Haar series for summation methods

Uniqueness of series in the Haar system summable by Toeplitz methods with positive matrices is investigated.Translated from Matematicheskie Zametki, Vol. 9, No. 4, pp. 449–458, April, 1971.     

To the Calculation of Widths and Shifts of Microwave Spectral lines

Within the framework of semiclassical collision theory, the method of rigorous calculation of widths and shifts of spectral lines is suggested that is not limited by the second order of perturbation theory and two-level approximation. Calculations are performed for spectral lines of a number of molecules perturbed by a classical dipole, and the deviation of the results obtained within the framework of rigorous theory from those obtained within the framework of the Anderson theory [1–4] is estimated.     

Asymmetry of the magnetic tuning characteristics of molecular masers

Radiophysics and Quantum Electronics -