Current Issue : October - December Volume : 2015 Issue Number : 4 Articles : 4 Articles
In this work, the temperature and frequency dependences of the real part of\nthe admittance [r(f, T)] of annealed nanocomposite films containing Co45\nFe45Zr10-based nanoparticles covered with native oxides and embedded in a\ndoped PbZrTiO3 ferroelectric matrix were studied. The nanocomposites\nstudied were deposited by ion sputtering a complex target in a mixed Ar/O2\natmosphere followed by a 15-min annealing process (with steps of 25 K) in air\nin the temperature range of 398 K �£ Ta �£ 573 K. The r(f, T) of the annealed\nsamples was measured in the temperature range of 77 K< Tp< 373 K at\nfrequencies of 50 Hz< f< 1 MHz. The observed r(f, T) dependences confirmed\nthat the annealed samples displayed the effects of negative capacitance\nover the whole frequency and temperature ranges studied because of the\npronounced oxidation of the nanoparticles. The r(f, T) dependences obtained\nare described using an earlier-developed AC hopping conductance model.\nComparisons between experimental and simulation results allow the model\nparameters to be estimated, such as the activation energies of the hopping\nconductance and the lifetimes of the electrons in the nanoparticles....
A design of a V-band Helix-Folded Waveguide (H-FWG) cascaded traveling wave tube (TWT) is presented. In this cascaded\nstructure, a digitized nonlinear theory model is put forward first to simulate these two types of the tubes by common process.\nThen, an initial design principle is proposed, which can design these two different kinds of tubes universally. Using this principle,\na high-gain helix TWT is carefully designed as a first stage amplifier followed by a FWG TWT to obtain high power. Simulations\npredict that a peak power of 800W with saturated gain of 60 dB from 55GHz to 60GHz can be achieved....
The rapid release of energy from reactive multilayer foils can create extreme\nlocal temperature gradients near substrate materials. In order to fully exploit\nthe potential of these materials, a better understanding of the interaction\nbetween the substrate or filler material and the foil is needed. Specifically, this\nwork investigates how variations in local properties within the substrate (i.e.\ndifferences between properties in constituent phases) can affect heat transport\ninto the substrate. This can affect the microstructural evolution observed\nwithin the substrate, which may affect the final joint properties. The effect of\nthe initial substrate microstructure on microstructural evolution within the\nheat-affected zone is evaluated experimentally in two Sn-Zn alloys and\nnumerical techniques are utilized to inform the analysis....
TCAD tools have been largely improved in the last decades in order to support both process and device complementary simulations\nwhich are usually based on continuously developed models following the technology progress. In this paper, we compare between\nexperimental and TCAD simulated results of two kinds of nanoscale devices: ultrathin body (UTB) and nanoscale Body (NSB)\nSOI-MOSFET devices, sharing the same W/L ratio but having a channel thickness ratio of 10 : 1 (46nm and 4.6 nm, resp.). The\nexperimental transfer I-V characteristics were found to be surprisingly different by several orders of magnitude. We analyzed\nthis result by considering the severe mobility degradation and the influence of a large gate voltage dependent series resistance\n(RSD). TCAD tools do not usually consider RSD to be either channel thickness or gate voltage dependent. After observing a clear\ndiscrepancy between the mobility values extracted from our measurements and those modeled by the available TCAD models, we\npropose a new semiempirical approach to model the transfer characteristics....
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