Simulation of hole-mobility in doped relaxed and strained Ge

As silicon CMOS begins to reach the limits of its performance, alternative channel materials are being considered. Thus there is renewed interest in employing Germanium for p-MOSFETs, due to the significant improvement in hole mobility as compared to silicon for undoped materials. Of considerable interest from a device point of view is the transport in doped layers. We investigate hole transport at high carrier-densities in doped Germanium layers using a bulk 6-band k·p Monte Carlo simulator, and show that both dynamic and multi-ion screening play a significant role in describing the resulting transport.     

Measurement of nonlinear mechanical properties of PDMS elastomer

This paper presents the measurement of the nonlinear mechanical properties of polydimethylsiloxane (PDMS) elastomer based on the mixing ratio of base polymer to curing agent. Strip-type PDMS samples with different mixing ratios were prepared using a simple coating, curing, and cutting process. A cyclic uniaxial tension test with a fixed magnitude of applied strain and a single-pull-to-failure tension test were performed with a micro-tensile tester at room temperature.Our new finding is that when the PDMS is mixed with excessive curing agent, stress softening occurs and residual strain exists in cyclic tension tests when the magnitude of the applied strain increases. For the PDMS-05 samples, in which the mixing ratio of base polymer to curing agent was 5 to 1, there were large differences in the stresses for the same strain level under loading and unloading during the first cycle with a 100% fixed strain amplitude, but the softening effect of the stress in the PDMS dropped rapidly starting from the second cycle.Nonlinear mechanical Neo-Hookean, third-order Mooney, and second-order Ogden models of three different PDMS films were computed from the stress-strain data. The results showed that all models were preferable for the small strain region of PDMS compared with other models. In the nonlinear, large strain region, only the second-order Ogden model properly described the mechanical behavior of the PDMS, while the Neo-Hookean and third-order Mooney-Rivlin models were too stiff or flexible in the measurement range. The bulk modulus of PDMS increased with the amount of curing agent in it. Therefore, the second-order Ogden model is preferable for analyzing the PDMS structure over the entire measurement range. This could provide reasonable mechanical models of PDMS for rapid computational prototyping and for designing active and passive components from PDMS.     

Spatial Wavefunction-Switched (SWS) InGaAs FETs with II–VI Gate Insulators

This paper presents the implementation of a novel InGaAs field-effect transistor (FET), using a ZnSe-ZnS-ZnMgS-ZnS stacked gate insulator, in a spatial wavefunction-switched (SWS) structural configuration. Unlike conventional FETs, SWS devices comprise two or more asymmetric coupled quantum wells (QWs). This feature enables carrier transfer vertically from one quantum well to another or laterally to the wells of adjacent SWS-FET devices by manipulation of the gate voltages (V _g). Observation of an extra peak (near both accumulation and inversion regions) in the capacitance–voltage data in an InGaAs-AlInAs two-quantum-well SWS structure is presented as evidence of spatial switching. The peaks are attributed to the appearance of carriers first in the lower well and subsequently their transfer to the upper well as the gate voltage is increased. The electrical characteristics of a fabricated SWS InGaAs FET are also presented along with simulations of capacitance–voltage (C–V) behavior, showing the effect of wavefunction switching between wells. Finally, logic operations involving simultaneous processing of multiple bits in a device, using coded spatial location of carriers in quantum well channels, are also described.     

Effect of oxide additives on the sintering behavior and electrical properties of strontium- and magnesium-doped lanthanum gallate

The effects of 14 different metal-oxide additives (metal = Mn, Fe, Co, Ni, Cu, B, Li, V, Zn, Si, Ca, Al, Bi, and Ba) on the sintering, phase purity, and electrical properties of strontium- and magnesium-doped lanthanum gallate (LSGM) are studied. The density, phase purity, and electrical conductivity depend closely on the sintering aids and sintering temperatures. The addition of V, Zn, Si, Co, and Fe improves the densification, phase purity, and electrical conductivity, with V showing the most promising effect on the low-temperature sintering of the phase-pure LSGM specimen with high conductivity.     

Carbon Nanotubes: Biocompatibility of Immobilized Aligned Carbon Nanotubes (Small 8/2011)

In vivo host responses to an electrode‐like array of aligned carbon nanotubes (ACNTs) embedded within a biopolymer sheet are reported. This biocompatibility study assesses the suitability of immobilized carbon nanotubes for bionic devices. Inflammatory responses and foreign‐body histiocytic reactions are not substantially elevated when compared to negative controls following 12 weeks implantation. A fibrous capsule isolates the implanted ACNTs from the surrounding muscle tissue. Filamentous nanotube fragments are engulfed by macrophages, and globular debris is incorporated into the fibrous capsule with no further reaction. Scattered leukocytes are observed, adherent to the ACNT surface. These data indicate that there is a minimal local foreign‐body response to immobilized ACNTs, that detached fragments are phagocytosed into an inert material, and that ACNTs do not attract high levels of surface fouling. Collectively, these results suggest that immobilized nanotube structures should be considered for further investigation as bionic components.     

谈商品通用名称与商标权的冲突——以天津狗不理包子案为视角

以天津狗不理集团有限公司诉济南市天丰园饭店案为视角,讨论了商品通用名称与他人注册商标在发生冲突时的解决机制,指出国家对于商标权的保护疆域与其他类型的知识产权的领地存在大量的交互,在部分情况下专利权、著作权、商品名称权等领域也被划入其中.对于这些争议的情形下应该如何取舍,现有的法律存在着诸多待确定的因素.     

First principle quantum calculation of the hydroxylation of 2-member ring defect on the amorphous silica surfaces

This study was conducted to find out the initiation mechanism of the hydroxylation of the 2-member ring on the amorphous silica surface. To do this, ab-initio molecular dynamics simulations were performed based on the first principle quantum calculation. The results suggest that the hydroxylation is initiated through the adsorption of water molecule on the surface of acidic silicon atom. The reaction pathway, the transition state and the energy barrier of the ring opening reaction were determined using the nudged elastic band method and dimer method. The present reaction mechanism and energy barrier were quite different from the previous cluster calculations.     

IBR-2 dynamics with power shedding

Calculations have shown that in the presence of power shedding the reactivity depends strongly on the moment of shedding relative to the start of the reactor cycle, the stopping time of the reactor after power shedding, and the number of sheddings. It is shown that reactivity effects due to power shedding continue to act for 2 days after shedding, after which these effects can be neglected. The total change of the reactivity after power shedding can range from 0.12 to –0.05%Δk/k. A region of negative reactivity forms in most practical cases after power shedding. The depth of this region can reach –0.05%Δk/k, and the duration varies from several hours to several tens of hours. Knowledge of the reactivity after power shedding makes it possible to determine more accurately the consequences of different emergency situations and to predict the critical state of the reactor when the reactor is once again brought up to power.     

A first-principles study on the electromechanical effect of graphene nanoribbon

The electromechanical effect of graphene nanoribbons (GNRs) is investigated via a first-principles method. The deformations of GNRs with zigzag shaped edges (ZGNR) and armchair shaped edges (AGNR) are considered. The nonlinear stress–strain relations are found for both of the AGNRs and the ZGNRs. The AGNRs seem to be stiffer than the ZGNRs as concluded from inspecting the Young's modulus and the ideal strength of GNRs. It is found that a mechanical deformation will affect the electronic structures of GNRs. The band gap of AGNRs exhibits sawtooth oscillations under strains and the oscillating strength is up to 1 eV. On the contrary, the band gap of ZGNRs is insensitive to strain. However, the band gap of ZGNRs will be reduced dramatically to zero as the compressive strain is greater than 0.17. The large variation of the band gap of AGNRs under strain indicates that deformation can provide an opportunity for tuning the band gap of an AGNR.     

SnO<Subscript>2</Subscript>-core/SiO<Subscript>x</Subscript>-shell coaxial whiskers with a needle-like morphology

Needle-shaped structures of tin oxide (SnO₂) were coated with a shell layer of SiO_x via a sputtering method. The diameters of the SiO_x-coated structures gradually became thinner, leading to the formation of sharp tips. The whiskers consisted of a crystalline SnO₂ core surrounded by an amorphous SiO_x shell. The photoluminescence (PL) spectrum with a Gaussian fitting exhibited yellow-green and orange light emission bands, and the overall shape and intensity of the PL spectrum were not changed by the SiO_xcoating. The results of this study suggest that sputtering can be employed to achieve the layered growth of shell layers on a variety of nanostructures.