排序方式: 共有6条查询结果,搜索用时 250 毫秒
1
1.
A common feature of the single-walled carbon-nanotube field-effect transistors fabricated to date has been the presence of a Schottky barrier at the nanotube--metal junctions. These energy barriers severely limit transistor conductance in the 'ON' state, and reduce the current delivery capability--a key determinant of device performance. Here we show that contacting semiconducting single-walled nanotubes by palladium, a noble metal with high work function and good wetting interactions with nanotubes, greatly reduces or eliminates the barriers for transport through the valence band of nanotubes. In situ modification of the electrode work function by hydrogen is carried out to shed light on the nature of the contacts. With Pd contacts, the 'ON' states of semiconducting nanotubes can behave like ohmically contacted ballistic metallic tubes, exhibiting room-temperature conductance near the ballistic transport limit of 4e(2)/h (refs 4-6), high current-carrying capability (approximately 25 micro A per tube), and Fabry-Perot interferences at low temperatures. Under high voltage operation, the current saturation appears to be set by backscattering of the charge carriers by optical phonons. High-performance ballistic nanotube field-effect transistors with zero or slightly negative Schottky barriers are thus realized. 相似文献
2.
朱士群 《苏州大学学报(医学版)》1990,6(2):195-199
Effects of multiplicatioe noise in transient laser intensity are investigated theoretically. Analytic solutions are calculated through a reduced Fokker-Planck equation and the results with different pump parameters are discussed. 相似文献
3.
Lundstrom K 《Cellular and molecular life sciences : CMLS》2006,63(22):2597-2607
Structure-based drug discovery has proven useful in improving and shortening the drug development process. The approach of
structural genomics to study a large number of targets in parallel has been commonly applied to protein families and even
whole genomes. Paradoxically, although membrane proteins represent the largest type of drug targets, up to 70% today, determination
of their structure has been modest compared to that of soluble proteins. Because membrane proteins are important for drug
discovery an emphasis has been placed on developing technologies and methods to determine membrane protein structures. Several
structural genomics initiatives have been established, focusing on the structural biology of membrane proteins.
Received 31 May 2006; received after revision 5 July 2006; accepted 9 August 2006 相似文献
4.
Lundstrom CC 《Nature》2000,403(6769):527-530
Recent seismological, geochemical and experimental observations suggest that, as mantle peridotite melts, the resulting basaltic liquid forms an interconnected network, culminating in the rapid ascent of the basalt relative to the surrounding solid matrix. Mantle melting is therefore a polybaric process, with melts produced over a range of pressures having differing chemical characteristics. Modelling and peridotite-melting experiments designed to simulate polybaric mantle melting generally assume that there is no interaction between melts generated at greater pressures and the overlying solid mantle at lower pressures. Beneath mid-ocean ridges, melts derived from greater depth are probably channelized during ascent, so preventing direct re-equilibration with shallow peridotite, as required by geochemical observations. I show here, however, that sodium in ascending melts will quickly diffuse into the melt formed within nearby peridotite at lower pressures. This process fundamentally changes the manner by which the peridotite melts, and can account for both the creation of silica-rich glass inclusions in mantle xenoliths and the anomalous melting modes recorded by abyssal peridotites. Increased melting of lithosphere and upwelling asthenosphere could result from this process without the need to invoke higher mantle temperatures. 相似文献
5.
A C3Cl-type(bcc)-semi-infinite ferrimagnet with a single-ion uniaxial anisotropy and a magnetic impurity layer is considered through combining Green‘s function theory with the transfer-mairx method.The effect of the anisotropy term and the impurity layer on surface spin wave specirum is discussed.The influence of the impurity layer‘s distance from the surface or surface spin woves is also concerned. 相似文献
6.
1