Modern Physics Letters B

Aluminum nitride (AlN) thin films were deposited on Si (111) substrates by low pressure metalorganic chemical vapor deposition system. The effects of the V/III ratios on the film structure and surface morphology were systematically studied. The chemical states and vibration modes of AlN films were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The optical absorption property of the AlN films, characterized by ultraviolet-visible-near infrared spectrophotometer, exhibited a sharp absorption near the wavelength of 206 nm. The AlN (002) preferential orientation growth was obtained at the V/III ratio of 10,000 and the preferential growth mechanism is presented in this paper according to the thermodynamics and kinetics process of the AlN growth.

Polycrystalline higher manganese silicide (MnSi_1.7, HMS) films with addition of aluminum and carbon are prepared on thermally-oxidized silicon substrates by electron beam evaporation and magnetron sputtering, respectively. An aluminum intermediate layer and a carbon cap layer are used as the doping sources. It is found that both the Seebeck coefficient and electrical resistivity are dependent on the amount of aluminum and carbon added to the films. The Seebeck coefficient changes a little in the temperature range 300 to 433 K and decreases considerably above 433 K when aluminum is added to the film. When carbon is added to the film, however, the Seebeck coefficient increases slightly. With addition of aluminum and carbon, the resistivity decreases. As a result, the thermoelectric power factor increases, especially for films with carbon addition. Several activation energies (0.022–0.20 eV) are observed from the curves of logarithm of resistivity versus reciprocal temperature. The larger activation energies of 0.35 and 0.51 eV are consistent with the energy band gaps for higher manganese silicides.

In this paper, a systematic method is presented to construct the Darboux transformation for generalized WKI equations. With the aid of symbolic computation, new soliton-like solutions for the GWKI equations are obtained by using its Darboux transformation.

We propose a scheme for implementing the Deutsch–Jozsa algorithm in ion-trap system. The scheme is based on resonant sideband excitation, which only requires resonant interactions. Thus the scheme is very simple and the quantum dynamics operation can be realized at a high speed, which is important in view of decoherence. The required experimental techniques are within the scope of what can be obtained in the ion-trap setup.

We study theoretically the symmetric property and coupling efficiency of the defect modes in a two-dimensional phononic crystal by calculating band structures, field distributions and transmission coefficients of the defect modes. The results show that the point defect could act as a microcavity surrounded by the phononic crystal, and the confining ability of the phononic crystal to the resonant modes strongly depends on the thickness of the phononic crystal. By investigating the transmission spectra, we also find that the defect modes cannot be absolutely excited by the normally incident plane waves. The transmission coefficients are calculated by using the eigen-mode match theory method under the supercell technique, which is applied to the phononic crystals with the defects for the first time.

A solid solution of phosphate and vanadate lead apatites Pb₁₀(PO₄)_6-x(VO₄)x(OH)₂ (x = 0.5, 1.0, 2.0, 3.0, and 6.0) were reduced with hydrogen gas at temperature 300°C for one hour. All these compounds were investigated by XRD and ESR spectroscopy. Only one reduced oxidation state, V⁴⁺, was detected. Two types of species-like isolated vanadium (+ 4) and clusters of V⁴⁺ were observed. The EPR powder spectrum computer simulations were performed using the program Simfonia from Bruker. Spin Hamiltonian parameters were also calculated. As the concentrations of vanadium ions increase to 2.0, the intensity of the ESR lines increases, and x = 3.0 the intensity of the ESR line decreases sharply. After this concentration, i.e. x > 3.0, there is again an increase in the intensity. The variation of the line shape and intensity of the ESR spectra can be attributed to increases in the hopping rate of the charge carriers (polarons) in different apatite compositions.

A model calculation of photofield emission is discussed in which initial state wave function has been deduced by using projection operator method of group theory. A spatial dependent vector potential is used to evaluate the matrix element for calculating the photofield emission current density.