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Diameter Dependence (diameter + dependence)
Selected AbstractsSilicon Nanowires: A Review on Aspects of their Growth and their Electrical PropertiesADVANCED MATERIALS, Issue 25-26 2009Volker Schmidt Abstract This paper summarizes some of the essential aspects of silicon-nanowire growth and of their electrical properties. In the first part, a brief description of the different growth techniques is given, though the general focus of this work is on chemical vapor deposition of silicon nanowires. The advantages and disadvantages of the different catalyst materials for silicon-wire growth are discussed at length. Thereafter, in the second part, three thermodynamic aspects of silicon-wire growth via the vapor,liquid,solid mechanism are presented and discussed. These are the expansion of the base of epitaxially grown Si wires, a stability criterion regarding the surface tension of the catalyst droplet, and the consequences of the Gibbs,Thomson effect for the silicon wire growth velocity. The third part is dedicated to the electrical properties of silicon nanowires. First, different silicon nanowire doping techniques are discussed. Attention is then focused on the diameter dependence of dopant ionization and the influence of interface trap states on the charge carrier density in silicon nanowires. It is concluded by a section on charge carrier mobility and mobility measurements. [source] Modeling and performance analysis of high-speed, low-power InAs nanowire field-effect transistorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2010M. Abul Khayer Abstract The performance metrics of InAs nanowire (NW) field-effect transistors (FETs) are investigated using an analytical 2-band model and a semiclassical ballistic transport model. The analysis of the diameter dependence of the current, gate delay, power-delay product, and energy-delay product of InAs NW FETs are presented. Because of their small density of states, relatively large diameter, , 60 nm, InAs NW FETs operate in the quantum capacitance limit (QCL). Both the energy-delay and power-delay products are reduced as the diameter is reduced, and optimum designs are obtained for diameters in the range of 10 , 40 nm. Power-delay product varies from 2 × 10,20 J to 63 × 10,20 J for all devices with a source Fermi level range of 0.1 , 0.2 eV. The gate delay time for all devices varies from 4 , 16 fs and decreases as the NW diameter increases. These NW FETs provide both ultra-low power switching and high-speed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Intermediate Frequency Modes of Single- and Double-Walled Carbon Nanotubes: A Raman Spectroscopic and In Situ Raman Spectroelectrochemical StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2006Martin Kalbac Dr. Abstract The intermediate frequency modes (IFM) of single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) were analyzed by Raman spectroscopy and in situ Raman spectroelectrochemistry. The inner and outer tubes of DWCNTs manifested themselves as distinct bands in the IFM region. This confirmed the diameter dependence of IFM frequencies. Furthermore, the analysis of inner tubes of DWCNTs allowed a more-precise assignment of the bands in the IFM region to features intrinsic for carbon nanotubes. Although the inner tubes in DWCNTs are assumed to be structurally perfect, the role of defects on IFM was discussed. The dependence of IFM on electrochemical charging was also studied. In situ spectroelectrochemical data provide a means to distinguish the bands of the outer and inner tubes. [source] Electronic Properties of Propylamine-Functionalized Single-Walled Carbon NanotubesCHEMPHYSCHEM, Issue 11 2010Matthias Müller Abstract We present resonant Raman measurements on single-walled carbon nanotubes (SWCNT) functionalized with propylamine groups at different degrees. Direct nucleophilic addition based on in situ generated primary amides is used for attaching n -propylamine to the sidewalls of SWCNTs. The influence of the amino functionalities on the electronic structure of the nanotubes is investigated. From the Raman resonance profiles of the radial breathing modes (RBMs), the chiral indices of the corresponding tubes are assigned. We observe significant redshifts of the transition energies and a broadening of the resonance windows due to chemical modification of SWCNTs. Similar redshifts are derived from the analysis of the NIR/Vis transmission spectrum. The relative Raman intensities of the functionalized samples and the evaluation of their transmission spectra indicate a diameter dependence of the reactivity as it has been observed for other moieties. By analyzing the defect induced D mode we observe a considerable degree of functionalization accompanied by an almost unharmed tube structure, which ensures that the observed effects are mainly driven by changes of the electronic structure. [source] | ||||||||||