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In this paper, we theoretically studied the electrical resistivity of the heavily Pr-doped YBa2Cu3O7−δ single crystal high-Tc superconductor cuprate. The proposed formulation expands the concept of relaxation times from frequency (energy) line widths for multiple scattering processes by leveraging electron quantum dynamics with the aid of the double-time electron Green function. A thorough analysis was carried out to investigate the effect of dopant-atom scattering as well as magnon scattering on the temperature and reduced frequency dependences of electrical resistivity in the temperature range of 20–300 K. An acceptable level of agreement between theory and experiment has been achieved. [ABSTRACT FROM AUTHOR]

The hydrogen isotopic composition (δ2H) of authigenic clay minerals has been used extensively in paleoclimate studies. The separation of clay minerals from sediments/soils, using various chemicals, is a prerequisite for isotope ratio measurements, where carbonate, Fe-(oxyhydr)oxides, and organic matter are removed successively from the sediments for a greater clay yield. The commonly adopted organic matter-removal method using hydrogen peroxide (H2O2) is thought to either alter directly the pristine δ2H values of the smectite clay minerals or to introduce organic hydrogen-bearing impurities through the ineffective removal of organic matter. The objective of the present study was to test whether H2O2 treatment can alter the δ2H values of kaolinite (Kln) by comparing two organic matter-removal methods, namely, H2O2 and disodium peroxodisulfate (Na2S2O8) combined with a neutral buffer. In doing so, kaolinite-rich, old (~56 Ma) sediment samples and pure kaolinite internal laboratory reference materials were used to understand the effectiveness and suitability of the above-mentioned methods in clay-sample preparation for δ2H measurements. The δ2H values of the H2O2-treated aliquots show smaller δ2H values than those for the Na2S2O8-treated aliquots. Estimated ambient water δ18O values (−4‰) from the Na2S2O8-treated aliquots agreed well with the bio-phosphate (fish vertebrae) based environmental water δ18O estimation (−3.3‰). The present study indicated, therefore, that δ2H values obtained after Na2S2O8 treatment are likely to be more realistic for paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]

A theoretical analysis of thermal conductivity of high-temperature superconductor cuprates, Pr1.3−xLa0.7CexCuO4 (PLCCO), has been successfully investigated. In this formulation, the idea of relaxation times and other scattering processes has been developed from frequency (energy) line widths using a quantum dynamical method. The major emphasis of this study is on the influence of phonon-dopant atom scattering on the thermal conductivity of Ce-doped PLCCO, as well as other prominent scattering processes such as electron-phonon, cubic and quartic anharmonic phonon, cubic and quartic phonon interference, and so on. The proposed theory has achieved a satisfactory agreement between theory and experiment. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the thermal conductivity of lightly Sr- and Zn-doped La2CuO4 high temperature superconductor cuprates has been analyzed auspiciously. We used a quantum dynamical technique to develop the symbol of relaxation time and other scattering processes from frequency (energy) line widths in this formulation. The primary focus of this study is the effect of phonon-dopant atom scattering on the thermal conductivity of doped La2CuO4, as well as other dominant scattering mechanisms such as electron–phonon, cubic and quartic anharmonic phonon, cubic and quartic phonon interference, and phonon-magnon, among others. An acceptable level of agreement between theory and experiment has been reached. [ABSTRACT FROM AUTHOR]

The thermal conductivity of high temperature superconductor cuprates (Zn-doped yttrium barium copper oxide (YBCO), YBa2(Cu1−xZnx)3O7−δ) is successfully analyzed in the temperature range of 0–200 K. Despite the fact that several theories have been offered to assess the thermal conductivity of high temperature superconductors since the pioneering work of Bardeen, Rickayzen, and Tewordt until now, a satisfactory solution has yet to be found. The idea of relaxation time and various scattering mechanisms has been developed from frequency line widths using a quantum dynamical approach in this current formulation. The influence of phonon–dopant atom scattering on the thermal conductivity of Zn-doped YBCO has been investigated in this study. This proposed theory has been able to achieve successful agreement between theory and experiment. [ABSTRACT FROM AUTHOR]

Si/Ge multilayers are of great technological importance as is evident from the research studies of the past two decades. Here, we have presented a method for the morphological and structural characterization of such MBE grown epitaxial Si/Ge superlattice structures using simultaneous analysis of x-ray reflectivity and x-ray diffraction data, respectively. The consistent analysis of the data collected in the Indian Beamline at Photon Factory Synchrotron have allowed for the determination of electron density and strain profile as a function of depth. [ABSTRACT FROM AUTHOR]

Titanium oxide (TiO2) high-k dielectric layers were deposited on the Si0.3Ge0.7 substrates by plasma enhanced chemical vapor deposition (PECVD) at low temperature (150 °C). To study the effects of annealing on the electrical properties, the TiO2 films were annealed in pure nitrogen ambient in the temperature range of 400–600 °C. Good electrical performance for the gate dielectrics was observed for the dielectric films annealed up to 500 °C, in terms of interface state density, leakage current, and charge trapping properties. Annealing at 600 °C is found to degrade the electrical properties due to Ge segregation and subsequent diffusion into the TiO2 layer. Schottky emission was found to be the dominant leakage current conduction mechanism in PECVD TiO2 films. [ABSTRACT FROM AUTHOR]

A critical analysis of charge carrier statistics influenced by quantum capacitance is carried out in order to predict the electrical performance of a nanoscale metal–oxide–semiconductor field-effect transistor (MOSFET) with a channel made of a monolayer tungsten diselenide (WSe2) two-dimensional (2D) crystal semiconductor. Since quantum capacitance originating from two-dimensional electron gas in a quantum well or an inversion layer does not completely screen the quasistatic electric field during applied gate voltage, the partial penetration of an external electric field through the 2D semiconductor channel will generate excess charge carriers; thus quantum capacitance will play an important role in determining the overall charge carrier density in the channel. Therefore, common methods used to extract charge carrier density in the channel for three-dimensional (3D) crystal semiconductors will yield inaccurate results when used for 2D crystal semiconductors. To address this issue, this study proposes a modified approach for extracting charge carrier density in WSe2-based 2D semiconductors by combining the appropriate carrier statistics with consideration of quantum capacitance. In addition, the study investigates the effect of interface traps on overall capacitance, which may influence the electrical performance of a nanoscale MOSFET with monolayer WSe2 as a channel material. [ABSTRACT FROM AUTHOR]