Modeling of the drain-induced barrier lowering effect and optimization for a dual-channel 4H silicon carbide metal semiconductor field effect transistor

A new analytical model to describe the drain-induced barrier lowering （DIBL） effect has been obtained by solving the two-dimensional （2D） Poisson＇s equation for the dual-channel 4H-SiC MESFET （DCFET）. Using this analytical model, we calculate the threshold voltage shift and the sub-threshold slope factor of the DCFET, which characterize the DIBL effect. The results show that they are significantly dependent on the drain bias, gate length as well as the thickness and doping concentration of the two channel layers. Based on this analytical model, the structure parameters of the DCFET have been optimized in order to suppress the DIBL effect and improve the performance.

Interaction of yttrium barrier and calcium-rich phase on production and properties of WC precursor powders and alloys

In order to reduce or eliminate the adverse effects of calcium impurity,the interaction of Ca and rare earth Y co-doping on the preparation of WC-Co cemented carbides was investigated.X-ray diffraction,scanning electron microscopy and transmission electron microscopy were employed to analyze the phase compositions,particle sizes and morphologies of them,respectively.The results show that the second type of"yttrium barrier effect"is observed and the adverse influence of Ca-rich phase on tungsten powder can be eliminated by it.The flexural strength and fracture toughness of YG6-0.01%Ca+0.09%Y alloy are 2199.5 MPa and 11.49 MPa·m^(1/2),showing improvement of 6.5% and 2.7% compared to YG6 alloy,respectively.The evolutions of Ca-rich phase and Y-rich phase at the every alloy preparation stage of WO_(3),W,WC and cemented carbides are obtained.Furthermore,the strengthening mechanism of WC-Co cemented carbide with co-addition of Ca and Y is proposed.

Impact of the Qinghai-Tibet Railway on Population Genetic Structure of the Toad-Headed Lizard,Phrynocephalus vlangalii

Using data from nine microsatellite DNA loci and a population genetic approach,we evaluate the barrier effect of the Qinghai-Tibet Railway on toad-headed lizard,Phrynocephalus vlangalii. The study area is along a 20 km stretch of the railway on northern Qinghai-Tibet Plateau,and this section of the railway was constructed between 1958–1979. Both assignment tests and analysis of molecular variance(AMOVA) were used for data analysis. We found significant genetic differentiation between the populations from the study area and those from a further southeastern area,which are separated by a 20 km gap. This suggests the existence of population substructure at a fine-scale. However,we did not detect any difference between samples from the western and eastern sides of the railway within the study area,and concluded that the railway may not impose a significant barrier effect on these lizard populations at the present time. Available suitable habitat alongside the railway and bridge underpasses may have facilitated the gene exchange between the sides. The relatively short time since the completion of the railway may not allow the differentiation to accumulate to a detectable level. Since the Qinghai-Tibet Plateau maintains a unique and fragile ecosystem,long-term monitoring of such man-made landscape features is imperative for protecting this ecosystem.

Gate-to-body tunneling current model for silicon-on-insulator MOSFETs

A gate-to-body tunneling current model for silicon-on-insulator （SOl） devices is simulated. As verified by the mea- sured data, the model, considering both gate voltage and drain voltage dependence as well as image force-induced barrier low effect, provides a better prediction of the tunneling current and gate-induced floating body effect than the BSIMSOI4 model. A delayed gate-induced floating body effect is also predicted by the model.

Enhanced radiation-induced narrow channel effects in 0.13-μm PDSOI nMOSFETs with shallow trench isolation

Total ionizing dose responses of different transistor geometries after being irradiated by ^（60）Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator（PD SOI） technology are investigated. The negative threshold voltage shift in an n-type metal-oxide semiconductor field effect transistor（nMOSFET） is inversely proportional to the channel width due to radiation-induced charges trapped in trench oxide, which is called the radiation-induced narrow channel effect（RINCE）.The analysis based on a charge sharing model and three-dimensional technology computer aided design（TCAD） simulations demonstrate that phenomenon. The radiation-induced leakage currents under different drain biases are also discussed in detail.

为一只双隧道的 4H 硅碳化物金属半导体地效果晶体管降低效果和优化的导致排水管的障碍当模特儿

A new analytical model to describe the drain-induced barrier lowering(DIBL) effect has been obtained by solving the two-dimensional(2D) Poisson’s equation for the dual-channel 4H-SiC MESFET(DCFET).Using this analytical model,we calculate the threshold voltage shift and the sub-threshold slope factor of the DCFET,which characterize the DIBL effect.The results show that they are significantly dependent on the drain bias,gate length as well as the thickness and doping concentration of the two channel layers.Based on this analytical model,the structure parameters of the DCFET have been optimized in order to suppress the DIBL effect and improve the performance.

Barrier effect of SiO2 shell over hollow CeO2/CuO@SiO2 catalysts for broadening temperature window of total CO conversion

The hollow inverse CeO2/CuO@SiO2 catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods,and characterized by multitechnique characterizations,such as SEM,TEM,XRD,H2-TPR,XPS and N2 adsorption-desorption techniques.It is found that the hollow shell is composed of CuO and SiO2,and CeO2 nanoparticles are coated on the surface of CuO@SiO2 support.And the CeO2/CuO@SiO2 catalyst with the Ce/Cu mass ratios of 1:1 denoted as 1 CeO2/CuO@SiO2,which possesses a maximum amount of highly dispersed copper species and medium-sized CuO as well as the highest concentration of oxygen vacancies,exhibits the highest catalytic activity and widest full CO conversion window.The barrier effect of the SiO2 shell effectively prevents the reduction of CuO species,which broadens temperature window of CO total conversion and enhances CO2 selectivity above 155℃over the 1 CeO2/CuO@SiO2 catalyst in comparison with the CuO-CeO2 and CeO2-CuO catalysts.

Simulation of electrical characteristics and structural optimization for small-scaled dual-gate GeOI MOSFET with high-k gate dielectric

The influences of the main structure and physical parameters of the dual-gate GeOl MOSFET on the device performance are investigated by using a TCAD 2D device simulator. A reasonable value range of germanium （Ge） channel thickness, doping concentration, gate oxide thickness and permittivity is determined by analyzing the on-state current, off-state current, short channel effect （SCE） and drain-induced barrier lowering （DIBL） effect of the GeOI MOSFET. When the channel thickness and its doping concentration are 10-18 nm and （5-9）×1017 cm-3, and the equivalent oxide thickness and permittivity of the gate dielectric are 0.8-1 nm and 15-30, respectively, excellent device performances of the small-scaled GeOI MOSFET can be achieved： on-state current of larger than 1475 μA/μm, off-state current of smaller than 0.1μA/μm, SCE-induced threshold-voltage drift of lower than 60 mV and DIBL-induced threshold-voltage drift of lower than 140 mV.

SBH adjustment characteristic of the dopant segregation process for NiSi/n-Si SJDs

By means of analyzing theⅠ-Ⅴcharacteristic curve of NiSi/n-Si Schottkyjunction diodes（NiSi/n-Si SJDs）, abstracting the effective Schottky barrier height（φ_（B,eff）） and the idealfactor ofNiSi/n-Si SJDs and measuring the sheet resistance of NiSi films（R_（NiSi））,we study the effects of different dopant segregation process parameters,including impurity implantation dose,segregation annealing temperature and segregation annealing time,on theφ_（B,eff） of NiSi/ n-Si SJDs and the resistance characteristic of NiSi films.In addition,the changing rules ofφ_（B,eff） and R_（NiSi） are discussed.