Lattice parameter and alloy fraction determination of Pb x Sn1−x Te films by RHEED double-patterns

A new technique to determine simultaneously the structure, the lattice parameter and the alloy stoichiometric composition of Pb _x Sn_1−x Te films r.f. sputtered into different substrates has been developed by making use of Reflection High Energy Electron Diffraction (RHEED) double-patterns. This method is available with all the materials for which the lattice constant is related to the alloy composition.     

Structure of gold island films

Structure of island gold films on carbon and glass substrates is investigated in the present work. The films were deposited by means of vacuum evaporation at constant pressure, temperature and deposition rate. Shapes, diameters, number densities and statistical distributions of island sizes are investigated in the region of the proper growth of island films. Experimental values are compared with the latest considerations on the coalescence theory. In the region of thicknesses where the number density of islands increases, their sizes do not change and the islands have the circular symmetry. In the region with the decreasing number density the island sizes increase, they have approximately the elliptical symmetry and the shapes of the statistical distributions of island sizes are different. It follows from the above facts that the mechanism of the origin of the two types of islands is different.     

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 T ₁=473 K and T ₂=973 K for 10 min. These films are characterized by the coercive field E _c=4.8 kV/cm and the spontaneous polarization P _s=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. __________ Translated from Fizika Tverdogo Tela, Vol. 44, No. 4, 2002, pp. 745–749. Original Russian Text Copyright ? 2002 by Sidorkin, Sigov, Khoviv, Yatsenko, Logacheva.     

Field effect in CdSe single-crystal films

The surface conductivity and effective mobility were studied as functions of the surface potential on CdSe single-crystal films having a conductivity of 1–10^–5 .cm^–1. The surface potential was varied by a constant external field. The formation of a conducting channel at the film surface is governed primarily by the change in the trapping factor as volume traps near the surface are filled. Field-effect data are used to evaluate the parameters of the exponential distribution of volume traps with respect to energy, the effective concentration of small donors, and the absolute values of the surface potential.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 3, pp.43–47, March, 1971.     

Carrier lifetime in single-crystal PbS films

The temperature dependence of the majority carrier lifetime was studied in single-crystal PbS films. In n- and p-type films in the range 300-200 ° K, increases exponentially with decreasing temperature, with an activation energy of e O. 17-0. 2 eV. This m dependence is assumed due to the trapping of minority carriers at deep levels. Below 160 ° K in the n-type films, does not depend on the temperature, while in the p-type films, decreases exponentially with an activation energy of 0. 11–0. 14 eV.Translated from Vysshikh Uchebnykh Zavedenii Fizika, No. 6, pp. 64–67, June, 1970.     

Spreading resistance microscopy of polycrystalline and single-crystal ferroelectric films

Thin films based on lead zirconate titanate with stoichiometric composition near the morphotropic boundary have been studied using atomic-force microscopy methods. The dependence of the local conductivity on the local polarization direction has been observed for all samples, independently of substrate type, deposition method, and film thickness. It has been shown that the current response to the applied voltage exhibits a long current relaxation, about several tens of seconds, which is two to three orders of magnitude greater than the current relaxation time in an external circuit, associated with the ferroelectric domain switching. The conductivity features have been explained by recharging of traps localized at ferroelectric grain boundaries near electrodes and involved in polarization charge screening.     

Conducting boron-doped single-crystal diamond films for high pressure research

Epitaxial boron-doped diamond films were grown by microwave plasma chemical vapor deposition for application as heating elements in high pressure diamond anvil cell devices. To a mixture of hydrogen, methane and oxygen, diborane concentrations of 240–1200 parts per million were added to prepare five diamond thin-film samples. Surface morphology has been observed to change depending on the amount of diborane added to the feed gas mixture. Single-crystal diamond film with a lowest room temperature resistivity of 18 mΩ cm was fabricated and temperature variation of resistivity was studied to a low temperature of 12 K. The observed minima in resistivity values with temperature for these samples have been attributed to a change in conduction mechanism from band conduction to hopping conduction. We also present a novel fabrication methodology for monocrystalline electrically conducting channels in diamond and present preliminary heating data with a boron-doped designer diamond anvil to 620 K at ambient pressure.     

Structural and morphological properties of ultrathin YBCO films grown on single-crystal substrates

Summary Epitaxial (001)-oriented ultrathin YBCO films of different thicknesses are deposited by Inverted Cylindrical Magnetron Sputtering (ICMS) on (100) MgO single-crystal substrates. The mean films stoichiometry is determined by Rutherford Backscattering (RBS). Auger Electron Spectroscopy (AES), X-ray Photoemission Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) are employed in order to analyse film growth, and identify spurious phases present in the samples. Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994.