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Presents a brief introduction about the 2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD) that was held in Tianjin, China, April 15–18, 2018.

YBa/sub 2/Cu/sub 3/O/sub 7/ (Y123) thin films were grown by pulsed laser deposition (PLD) on YSZ (100), SrTiO3 (100), and LaAlO3 (100) single crystal substrates. Prior to the film deposition, a discontinuous layer of Ag nano-dots was deposited on the substrates. The Y123 films grown on such surfaces modified with Ag nano-dots were characterized by Atomic Force Microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM), AC susceptibility and DC magnetization. The effects of the density of Ag nano-dots, which was controlled by the numbers of PLD shots, on the microstructures and resultant critical current density J/sub c/ have been studied systematically. Results showed that at fixed physical deposition conditions J/sub c/ increased monotonically with number of Ag shots, n, for films grown on both STO and LAO substrates. At 77 K, the J/sub c/ increased from 10/sup 6/ to 3.2/spl times/10/sup 6/ A/cm/sup 2/ for LAO and from 8/spl times/10/sup 5/ to 3.5/spl times/106 A/cm/sup 2/ for STO as n increased from 0 to 150. At 5 K, the enhancement of J/sub c/ was approximately four times at both low and high fields. However, for films grown on YSZ substrate, J/sub c/ increased from 2/spl times/10/sup 5/ to 2/spl times/10/sup 6/ A/cm/sup 2/ as Ag shots increased from 0 to 30, and decreased to 9/spl times/10/sup 5/ for n/spl ges/60. Detailed microstructure investigations indicated that the crystallinity and ab alignment gradually improved as the number of Ag-nano-dots increased.

Magnetic hysteresis and magnetic relaxation measurements have been performed to study vortex pinning behaviors for pure, Fe doped and heavily Pb doped Bi2212 single crystals. Unlike pure and Fe doped Bi2212 crystals, heavily Pb doped crystal showed strong vortex pinning behavior. We interpret the strong pinning in heavily Pb doped Bi2212 single crystals as arising from the improved Josephson coupling in Bi2212 single crystal after heavy Pb doping. In heavily Pb doped single Bi2212 crystals, H/sub dis/(T) was observed to decrease with increasing T. Here, H/sub dis/(T) is an order-disorder field that separates a weakly elastically disordered vortex lattice from a plastically disordered vortex solid. However, in pure and Fe doped Bi2212 single crystals, H/sub dis/(T) was observed to be temperature independent. We also report a significant shift of T/sub CR/, a crossover temperature separating two pinning regimes, toward higher temperatures with heavy Pb doping of Bi2212 single crystals. On the other hand T/sub CR/ did not shift with Fe doping of Bi2212 single crystals. It is argued that the temperature dependence of H/sub dis/(T) and the shift of T/sub CR/ in heavily Pb doped Bi2212 crystals was related to the enhanced c-axis conductivity caused by the Pb situated between the CuO/sub 2/ layers and imposing a 3D characteristic on the vortex lattice.

Transport critical current (Ic) was measured for MgB2/Fe round wires, with magnetic field oriented perpendicular to the wire and parallel to it. Measurements were made on a wire with pure MgB2 core and another wire where MgB2 core was doped with nano-size SiC. This doping strongly improved the vortex pinning in MgB2. The field dependence of Ic was strongly improved due to the presence of the iron sheath. At 30K, Ic did not depend on the field for fields between 0.09 and 0.7T. At lower temperatures, Ic increased with the field, after initial decrease, resembling a "peak effect". This effect was extended to higher fields as the temperature went down: at 10K the peak appeared at 3.5T. This improvement was not due to mere magnetic shielding by iron, but more likely to an interaction between the iron sheath and superconductor. Improvement of vortex pinning did not affect the range of fields within which this effect was observed.

Two-dimensional energy-dependent substrate current models are described for NMOS and PMOS devices that have been developed using a multi-contour approach. The new models offer a significant improvement in the calculation of substrate current due to a more accurate calculation of the average energy as compared to the local-field model. The models are implemented in a post-processing manner by applying a one-dimensional energy conservation equation to each of many current contours in order to generate a two-dimensional representation of average energy and impact ionization rate, that is then integrated to calculate the substrate current. The new models have been compared to substrate current characteristics of a variety of NMOS and PMOS devices for a wide range of bias conditions and channel lengths, and very good agreement has been obtained with a single set of model parameters. An additional significance of this work is the enhancement of the standard multi-contour model by an energy-sink term that results in an improved prediction of the impact ionization process in PMOSFET's. >

A multicurrent contour, average-energy-based, substrate current model for silicon submicrometer NMOSFETs is presented as a significant improvement to the local-field model that is commonly used in modern drift-diffusion device simulators. The model is implemented as a post-processor by applying a one-dimensional energy conservation equation to many current contours in order to generate a two-dimensional representation of average energy and impact ionization rate which is integrated to calculate the substrate current. Comparisons of simulations and experimental I-V curves for both simple and LDD MOSFETs are presented. Outstanding agreement has been obtained over a wide range of bias conditions and channel lengths. >

Summary form only given. The authors present a more rigorous hydrodynamic postprocessing approach than that implemented by J.W. Slotboom et al. (1991). The proposed model is 2-D and is based on the 1-D form of energy equation described by R.K. Cook et al. (1982), implemented into the 2-D drift-diffusion simulator PISCES as a postprocessor to calculate substrate current. This new approach involves the determination of the average energy along many current contours using the 1-D energy conservation equation and the local electric fields calculated by PISCES along each current path. The impact ionization rates are calculated using an energy parameterized form of the Chynoweth law. These coefficients along with the current densities calculated by PISCES are then used to determine the 2-D distribution of generation rates, and the generation rates are integrated over the entire 2-D device structure to calculate the substrate current. The authors have demonstrated very good agreement with substrate current characteristics measured on a broad range of LDD (lightly doped drain) NMOSFET devices with varying channel lengths, gate biases, and drain biases. >