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.

Full characterization of anisotropic diffuse light.

Abstract: We demonstrate a method for fully characterizing diffuse transport of light in a statistically anisotropic opaque material. Our technique provides a simple means of determining all parameters governing anisotropic diffusion. Anisotropy in the diffusion constant, the mean free path, and the extrapolation length are, for the first time, determined independently. These results show that the anisotropic diffusion model is effective for modeling transport in anisotropic samples, providing that the light is allowed to travel several times the transport mean free path from the source.

Measurement of the hot electron mean free path and the momentum relaxation rate in GaN

Abstract: We present a method for measuring the mean free path and extracting the momentum relaxation time of hot electrons in GaN using the hot electron transistor (HET). In this device, electrons are injected over a high energy emitter barrier into the base where they experience quasi-ballistic transport well above the conduction band edge. After traversing the base, high energy electrons either surmount the base-collector barrier and become collector current or reflect off the barrier and become base current. We fabricate HETs with various base thicknesses and measure the common emitter transfer ratio (α) for each device. The mean free path is extracted by fitting α to a decaying exponential as a function of base width and the relaxation time is computed using a suitable injection velocity. For devices with an injection energy of ∼1 eV, we measure a hot electron mean free path of 14 nm and calculate a momentum relaxation time of 16 fs. These values are in agreement with theoretical calculations where longitudinal optical phonon scattering is the dominant momentum relaxation mechanism.

Electronic properties of selenium-tellurium melts

Abstract: The electronic transport phenomena of SeTe melts are analyzed with two models of density of states. At low temperatures ( T ∗ ) a semiconducting behaviour is observed and we calculate activation energies involved in conducting and thermopower when only hole transport is taken into account. The optical absorption results give the width of optical gap and its temperature dependence. At high temperatures ( T > T ∗ ) a metallic conduction, with a short mean free path occurs so that a pseudogap and onset of localization near the Fermi level are likely when the Mott's criterion is satisfied. The observation of switching phenomena in liquid Se-rich alloys strengthens the analogy with amorphous semiconductors.

Electric field distribution in the cathode-fall region of an abnormal glow discharge in hydrogen: experiment and theory

Abstract: We present the results of an experimental and theoretical study of the electric field distribution in the cathode-fall (CF) region of an obstructed abnormal glow discharge in hydrogen. The distribution of electric field strength was measured using an improved Stark polarization spectroscopy technique of the hydrogen Balmer beta line profile. The developed technique extends field measurements to the low-field region while remaining in good agreement at larger field strengths with the well established Stark polarization peak separation electric field measurement technique. The experimental electric field distribution is modeled by a simple analytical formula, adopted after consideration of elementary processes relevant in the CF. It fits the experimental distribution within error bars and consequently enables determination of the CF parameters such as its thickness and the mean free path for electrons in the CF region.