Stabilization of electrochemical formation of macropores inn-Si

The process of macropore formation in silicon electrodes has been investigated by electrochemical etching. The stationary distribution of the concentration of non-equilibrium holes with thickness of n-Si films on irradiation with strongly absorbed light on the side opposite to the semiconductor-electrolyte contact has been calculated. A regime for irradiation of the semiconductor anode and the electric field intensity during pore formation which provides a stationary concentration of holes at the extremities of the macropores has been determined. The relation of the diameters of cylindrical pores to the extent of doping of n-Si with additives (to the lifetime of non-equilibrium charge carrier) has been studied. Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 45 Prospekt Nauki, Kiev 252650, Ukraine. Translated from teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 5, pp. 314–318, September–October, 1998.     

Interrelation of intrinsic and extrinsic defects – congruent, stoichiometric, and regularly ordered lithium niobate

A new approach to the intrinsic and extrinsic defect subsystems, considering them as one integrated functional system, is developed for complex oxides. The strong interrelation of these subsystems becomes especially apparent when concentrations of both defect classes are comparable. A new parameter, reflecting the total intrinsic defect concentration, is introduced to determine the degree of crystal imperfection. The necessity of at least two calibrated samples – congruent and regularly ordered crystals – is substantiated. The accuracy by which the parameter can be determined can serve as a criterion in comparison of different methods of crystal characterisation. A procedure for crystal calibration by several physical characteristics is illustrated. Such a heuristic generalisation of the concept of mutual correlation of the whole defect system and the material only became possible on the basis of experimental and theoretical study of large numbers of LiNbO₃ crystals. The spectra of EPR, NMR, ENDOR, and other properties of crystals with different compositions, diverse modifiers (K, Mg,...), and various probe impurities have been analysed. It is found that crystals with vanishingly small concentration of intrinsic defects offer extraordinary informative opportunities. Their micro- and macroscopic properties are discussed. The developed ideas have a general character; therefore they should also be valid for other non-stoichiometric complex oxides. Received: 3 December 1998 / Revised version: 15 February 1999 / Published online: 12 April 1999     

Development and application of an AFM probe soft approach method

The soft approach of an AFM probe to a sample’s surface is examined. Our method allows the approach of extremely fragile probes and differs advantageously from other known methods in its much lower degree of impact on the sample. At the same time, the proposed method is not much slower than the fastest available methods. Corresponding experimental results are presented.     

Solvability of boundary value problems for fourth order systems of differential equations

Translated from Matematicheskie Zametki, Vol. 50, No. 2, pp. 105–110, August, 1991.     

Convergence of solutions of stochastic differential equations to the Arratia flow

We consider the solution x _ε of the equation

Properties of a wiener process with coalescence

A Wiener process with coalescence and its analog are discussed. We prove the existence of an initial distribution with preset final probabilities for this analog and investigate the problem of the existence of such distributions concentrated at a single point or absolutely continuous with respect to the Lebesgue measure. The behavior of a semigroup of a Wiener process with coalescence in the two-dimensional case and properties of a Wiener flow with coalescence are studied. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 4, pp. 489–504, April, 2006.