Shot-noise suppression by Fermi and Coulomb correlations in ballistic conductors

Abstract

We investigate the injection of degenerate Fermi-Dirac electrons into a multimode ballistic conductor under the space-charge-limited regime. The nonequilibrium current fluctuations were found to be suppressed by both Coulomb and Fermi correlations. We show that the Fermi shot-noise-suppression factor is limited below by the value ${2k}_{B}T/{\ensuremath{\varepsilon}}_{F},$ where T is the temperature and ${\ensuremath{\varepsilon}}_{F}$ the Fermi energy of the injected electrons. The Coulomb noise suppression factor may attain much lower values ${\ensuremath{\varepsilon}}_{F}/2qU,$ because of its dependence on the applied bias $U\ensuremath{\gg}{k}_{B}T/q.$ The asymptotic behavior of the overall shot-noise suppression factor in a high degenerate limit was found to be ${k}_{B}T/qU,$ independent of the material parameters.