TABLE OF CONTENTS Hot-electron transport regimes are dependent on multiple parameters and factors. First of all, the properties of the electron band structure effective masses, non-parabolicity parameters, upper valley characteristics, etc. should be taken into account. Then, the kinetic factors such as momentum and energy relaxation mechanisms and intervalley scattering are of importance. Other parameters and factors controlling transport regimes include the carrier concentration, physical geometry, and bias conditions. Let us briefly discuss the influence of these factors.
The magnitude of the carrier concentration determines the role of e-e interaction under transport regimes. At large carrier concentrations, e-e scattering dominates over other relaxation mechanisms and the electron subsystem has common ( collective ) momentum and energy budgets. Nonequilibrium carrier distributions in the momentum and energy spaces occur in the form close to the shifted Maxwellian function (or Fermi-Dirac function) with an effective electron temperature and a drift velocity. At low concentrations where e-e scattering does not prevail, the electrons have independent ( individual ) momentum and energy budgets, and the electron distribution generally has a non-Maxwellian form frequently showing a strong anisotropy, inverted population, and other nontrivial features.
Geometrical factors (sample and device feature sizes, inter contact distances, etc.) as well as the character of electron confinement also affect the hot-electron kinetics. Indeed, when a characteristic size of a device becomes comparable to one of the semiclassical kinetic lengths (the intervalley scattering length, energy relaxation length, mean free path, etc.) the electron kinetics becomes dependent on the device size. Correspondingly,...
