Interpreting the optical spectra of trace Fe2+ in layer silicates

Estimates have been made of Fe²⁺ term splittings in axial crystalline fields. It is found that all three long-wave bands in the optical spectrum are due to Fe²⁺ Fe³⁺ charge transfer, while the splitting of ⁵T_2g and ⁵E_g occurs in low-symmetry fields. Experimental evidence is presented for these calculations.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 464–468, July–August 1987.     

SIMS diagnostics of the structure of nanometer-sized semiconducting layers doped with impurities

The possibility of analyzing the structure of nanometer-sized silicon layers doped with boron and antimony (at a concentration level of 10⁻²–10⁻³ at %) via secondary-ion mass spectrometry (SIMS) is investigated. A recoil-atom implantation process has been evaluated from the standpoint of its contribution into the total recorded signal of secondary ions of impurities. It is demonstrated that SIMS can be used for qualitative determination of the structure formed in doped δ-layers.     

Jahn-Teller effect in systems of cubic symmetry. Linear 4Tεt2 problem

The normal vibrations of ε_g and τ_2g symmetry are shown to reduce the O_h symmetry to C_i. The position and depth of the adiabatic potential minima strongly depend upon the ratio of vibronic and spin—orbin interactions.     

Emission Theory of the Sputtering of Amorphous Materials: Self-Sputtering

The dependences of the coefficient of self-sputtering on the type of accelerated ions, their energy, and the angle of incidence on a target are calculated. Satisfactory coincidence between the calculated and experimental results is obtained for С–С and W–W systems. Two mechanisms of the entry of secondary particles into a flow of sputtered atoms are proposed.     

Precision depth profiling of nanoelectronic structures using secondary molecular ions in secondary-ion mass spectrometry

A method for improving SIMS depth profiling by recording secondary molecular ions is proposed. Experimental studies of SiGe and AlGaAs nanometer-scale test structures, and of boron-doped Si with an energy of 5 keV showed improved secondary-ion mass spectroscopy depth resolution when recording secondary molecular ions. A physical model that considers the molecular ion dissociation energy to be a decisive parameter is discussed.     

Changes in the composition of the surface layer of silicon under sputtering by oxygen and cesium ion beams

The distribution profiles of primary ion beams of electroactive atoms (cesium and oxygen) in silicon samples have been investigated experimentally. It is demonstrated that the initial chemical composition of a sample is modified due to the implantation of primary ions at depths of up to 5 nm from its surface. A mechanism responsible for the enhancement of the secondary-ion yield during target sputtering by the chemically active elements has been proposed.     

Inelastic collisions of medium energy atomic elements in solids

The stopping of medium atomic elements in solids has been calculated in the framework of classical approximation, taking into account elastic and inelastic collisions. The calculations are based on the 1) revised equations for the law of energy and impulse conservation, which were earlier used to describe inelastic collisions of atomic particles, 2) theory of quasi-small angle scattering, 3) power potential of LNS, and 4) limitation of the maximum distance of atoms approach determined by the interatomic distance in solids. Analytical equations have been obtained to calculate 1) a differential cross-section of elastic scattering in the presence of inelastic collisions, 2) energy transferred, 3) cross-sections of elastic and inelastic stopping, and penetration depth. Implantation into solids was found to be of threshold character.