Papers by Author: Mariya G. Ganchenkova

Abstract: In this paper we study the effect of chemical environment and elastic strains, which can arise in layered heterostructures due to the lattice parameter mismatch, on the vacancy formation energy in random Si-Ge compounds. Ab initio calculations demonstrate a number of simple trends characterizing the vacancy formation energy dependence on vacancy charge, the number of Ge atoms in its neighbourhood and on the magnitude of elastic strains. The obtained parameters of vacancy-germanium interaction indicate, in particular, a tendency for preferential vacancy accumulation in SiGe region of Si/SiGe/Si layered structures, which is confirmed here by Monte- Carlo simulation of high-temperature vacancy annealing and agrees well with recent experimental observations.

Abstract: The effect of compressive and tensile plane-stress loading on formation energies and electronic properties of vacancies and divacancies in silicon are studied by first-principles approach for in-plane strains up to 0.7%. It is demonstrated that contributions to defect formation energies from the elastic lattice relaxation and from the band structure modification respond to stress in a different manner, leading to noticeable different behaviour of formation energies for different charges states. The most stable vacancy charge states at different Fermi level are shown to be sensitive to strain magnitude and sign. This results in the strain-induced shifts and even disappearance of some of thermal ionization levels of vacancies and divacancies in the band gap.

Abstract: The paper presents the results of experimental in-situ observations of cobalt disilicide nucleation in Co+ implanted silicon and ab initio simulations of energies of small cobalt and cobaltvacancy clusters. Based on these results, microscopic nucleation mechanisms of different types of CoSi2 precipitates are discussed.

Abstract: In this paper we discuss possible mechanisms of PV annealing in Si. Our approach includes a combination of density functional theory and lattice kinetic Monte-Carlo (LKMC) simulations. The density functional theory is used to find the binding energies and jump barriers for P-V pair at different separations (from one to three interatomic bonds between complex constituents) and in different charge states. The mobility of the complex is simulated by LKMC with event probabilities calculated based on the energies from ab-initio calculations. .