O. B. Yatsenko

Electrical properties of thin PbTe films on Si substrates

An attempt was made to reduce the carrier concentration in thin PbTe films on Si substrates by optimizing deposition conditions. A modified hot-wall method was used for reproducible growth ofp-type films with 5 × 1015 < p(77 K) < 5 × 1017 cm-3 andn-type films with 3 × 1015 < n(77 K) < 5 × 1016 cm-3. The IR irradiation was found to have a significant effect on the temperature variation of film resistance. The activation energy of the IR-sensitivity centers was determined to be 0.11 ± 0.005 eV at room temperature and 0.18 ± 0.005 eV between 150 and 180 K.

Ice Melting and Crystallization in Binary Water–Salt Systems

Correlations are revealed between the phase diagrams of water–salt systems, the crystallization and melting behaviors of ice in such systems, and the physicochemical properties of Group I and II chlorides and sulfates (cation radius and heat of solution in water). It is shown that kinetic studies of ice melting may yield further insight into the mechanisms of phase transformations and component distribution in different aqueous systems.

Microhardness and density of PbTe1−xHalx (Hal = Cl, Br, I) solid solutions

Microhardness data for PbTe1−xHalx (Hal = Cl, Br, I) solid solutions are used to evaluate the halogen solubility in PbTe. The density of the PbTe1−xHalx solid solutions is shown to drop with increasing halogen content, with a rate decreasing in the order Cl > Br > I. The density data are interpreted in terms of self-compensation.

Transport Properties of Ga-Doped PbTe Thin Films on Si Substrates

Thin PbTe films on Si substrates were doped with Ga via annealing in the vapor produced by heating a Ga(l) + GaTe(s) mixture (GaTe(s) + L1+ Vequilibrium). Electrical measurements showed that the vapor-phase doping reduced the hole concentration in the films by more than two orders of magnitude. IR irradiation was found to reduce the resistivity of the PbTe films by a factor of 40–100. The films annealed in the vapor over GaTe(s) + L1for the longest time exhibited an anomalous temperature variation of resistance, which was interpreted as due to the limited Ga solubility in PbTe.

Lattice parameter of PbTe1−x Cl x solid solutions

The lattice parameter of PbTe1−xClx solid solutions is shown to be a nonmonotonic function of chlorine content, with a minimum at x = 0.005. The results are interpreted in terms of a self-compensation model.

Low-Temperature Crystal Growth in Aqueous Systems

The conditions for the crystal growth of various substances (salts, amino acids, and others) in aqueous systems between the eutectic (≤0°C) and room temperatures were studied. The ingots prepared by freezing solutions of required compositions were used as source material for crystal growth (recrystallization). The growth and properties of the crystals were shown to be controlled by the supersaturation which is maintained at the desired level by means of fractional ingot melting.

Plasma Synthesis of Thin Copper Silicide Films on Single-Crystal Silicon

Thin copper silicide films were produced on single-crystal silicon by plasma synthesis via liquid-phase magnetron sputtering. The interaction of high-energy Cu ions with the negatively biased substrate was shown to play a key role in the synthesis of copper silicides. The effects of the deposition time and copper ion energy on the structure, phase composition, and electrical properties of the resulting films were studied.

Lead titanate ferroelectric films on single-crystal silicon

This paper reports on the results of investigations into the phase transformations observed in Pb/Ti/Si and Ti/Pb/Si thin-film heterostructures upon layer-by-layer magnetron sputtering of lead and titanium onto a single-crystal silicon substrate and subsequent annealing in an oxygen atmosphere. It is shown that the dielectric properties of lead titanate films depend on the order of sputtering of lead and titanium metal layers onto the surface of single-crystal silicon. The ferroelectric properties are revealed in 3000-nm-thick lead titanate films prepared by two-stage annealing of the Pb/Ti/Si thin-film heterostructure (with the upper lead layer) at T1=473 K and T2=973 K for 10 min. These films are characterized by the coercive field Ec=4.8 kV/cm and the spontaneous polarization Ps=16.8 µC/cm2. The lead titanate films produced by annealing of the Ti/Pb/Si thin-film heterostructure (with the upper titanium layer) do not possess ferroelectric properties but exhibit properties of a conventional dielectric.

Preparation of thin lead stannate layers on single-crystal silicon

Thin films containing lead stannates were prepared on single-crystal silicon substrates by annealing Sn/Pb/Si and Pb/Sn/Si structures produced by magnetron sputtering with the use of solid Sn targets and solid or liquid (self-sputtering) Pb targets. The structures were annealed in flowing oxygen for 10 min at temperatures in the range 520–1120 K. The phase composition of the films is found to strongly depend on the Pb deposition procedure, the sequence of layers in the as-grown heterostructure, and thermal oxidation conditions.

Thermal oxidation of Ti and pb thin films deposited on single-crystal silicon

Thin Pb–Ti–O films on single-crystal Si were prepared by magnetron sputtering followed by thermal oxidation of Pb/Ti/Si and Ti/Pb/Si structures. Oxidation of Pb/Ti bilayers was found to yield lead oxides, which then react with Ti to form lead titanate. Ti/Pb bilayers on Si could be converted into stoichiometric lead titanate, through titanium and lead oxides, by oxidation between 870 and 1070 K. Some of the films exhibited ferroelectric properties.