Topic
Mean free path
About: Mean free path is a research topic. Over the lifetime, 4412 publications have been published within this topic receiving 114418 citations.
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TL;DR: It is found that an unexpectedly low percentage (∼0.04%) of phonons carry out the heat conduction process in SiGe nanowires, and that the ballistic phonons display properties including non-additive thermal resistances in series, unconventional contact thermal resistance, and unusual robustness against external perturbations.
Abstract: SiGe nanowires exhibit ballistic thermal conduction at room temperature with a long phonon mean free path.
162 citations
TL;DR: In this paper, the resistance of single and multi-wall carbon nanotubes (MWCNs) has been investigated and compared with the model presented in this paper for single and few-wall MCN.
Abstract: Equivalent circuit models are presented for the resistance of single- and multi-wall carbon nanotubes (MWCNs) that capture various electron-phonon scattering mechanisms as well as changes in the number of conduction channels as a function of temperature. For single- and few-wall nanotubes, the temperature coefficient of resistance (TCR) is always positive and increases with length. It reaches 1/(T-200 K) for lengths much larger than the electron mean free path, where T is the temperature in kelvin. For MWCNs with large diameters (>20 nm), TCR varies from -1/T to +0.66/(T-200 K) as the length varies from zero to very large values
161 citations
TL;DR: In this article, a simple expression for the ionisation coefficient for impact ionisation is derived on the basis of a new approach which exploits the difference between momentum and energy-relaxation rates for hot electrons.
Abstract: A simple analytic expression for the ionisation coefficient for impact ionisation is derived on the basis of a new approach which exploits the difference between momentum- and energy-relaxation rates for hot electrons. The basic mechanism whereby an electron gains sufficient energy to ionise is lucky to drift in which the electrons relax momentum but not energy. The electrons gain energy by drift and not by ballistic motion, and a few lucky ones reach the threshold. Those which thermalise may also contribute through the lucky-drift mechanism, starting from the average hot-electron energy. Good agreement with Baraff's theory is obtained. It is shown that neither the Schockley lucky electron nor the Wolff thermalised electron contribute significantly, in agreement with Baraff. However, the concept of Schockley's lucky electron is an essential part of the lucky-drift mechanism. The theory is simply extended to accommodate electrons injected at energies above zero, and some calculations are presented on this topic. A discussion is given of the effect of real band structure and it is concluded that the theory based on parabolic bands remains good provided the mean free path is taken as an average quantity over the relevant energy range. It is argued that the theory has wide application to semiconductors with moderate-to-large energy gaps because of the predominance of nonpolar scattering at high energies. A specific model of a nonparabolic band structure is discussed in which the electron distribution function has a Gaussian form, rather than the Maxwellian form associated with parabolic bands, and a weak negative differential resistance is exhibited.
160 citations
TL;DR: In this paper, proper treatment of the nonlocality of the nuclear optical potential resolved much of the apparent discrepancy between previous theoretical calculations and empirical values of the nucleon mean free path.
Abstract: It is shown that proper treatment of the nonlocality of the nuclear optical potential resolves much of the apparent discrepancy between previous theoretical calculations and empirical values of the nucleon mean free path.
160 citations
TL;DR: In this article, the electron properties in a parallel plate capacitively coupled rf discharge were studied with results from a Monte-Carlo simulation, and the dc component of the sheath potential was found to be a function of the ratio λ/d, where is the electron mean free path and d is the electrode spacing.
Abstract: Electron properties in a parallel plate capacitively coupled rf discharge are studied with results from a Monte‐Carlo simulation. Time averaged, spatially dependent electron distributions are computed by integrating, in time, electron trajectories as a function of position while oscillating the applied electric field at rf frequencies. The dc component of the sheath potential is solved for in a self‐consistent manner during the simulation. For conditions where the secondary emission coefficient for electrons from the electrodes is large, the electron distribution is spatially differentiated, being dominated by an e‐beam component near the electrodes while being nearly in equilibrium with the applied electric field in the body of the plasma. The dc component of the sheath potential is found to be a function of the ratio λ/d, where λ is the electron mean free path and d is the electrode spacing.
159 citations