Low-frequency shot noise in phonon-assisted resonant magnetotunneling

Abstract

A theory of low-frequency shot noise in a resonant tunneling double-barrier device has been worked out. The calculations have been carried out within the coherent tunneling model; only the electron-phonon interaction inside the quantum well is taken into account. The average current ${\mathrm{I}}_{\mathrm{dc}}$ and the noise spectrum S(\ensuremath{\omega}) are expressed in terms of intrawell two-, three-, and four-electron Green's functions. The expression is valid, in principle, for arbitrary temperatures and for any type of intrawell scattering. We use it to analyze excess noise in phonon-assisted resonant tunneling through a double-barrier device at zero temperature and to the lowest order in the electron-phonon interaction. Our results show that the suppression of excess noise due to a correlation in electron transport is expected for both elastic and inelastic tunneling. In particular, we note that the contribution of the elastic processes to the ratio S(\ensuremath{\omega})/${\mathrm{eI}}_{\mathrm{dc}}$ is very sensitive to asymmetry of the tunneling barrier heights. Such a sensitivity is reduced for phonon-assisted processes.