LOW-FREQUENCY SHOT-NOISE IN PHONON-ASSISTED RESONANT MAGNETOTUNNELING

A theory of low-frequency shot noise in a resonant tunneling double-ba rrier device has been worked out. The calculations have been carried o ut within the coherent tunneling model; only the electron-phonon inter action inside the quantum well is taken into account. The average curr ent I-dc and the noise spectrum S(omega) are expressed in terms of int rawell two-, three-, and four-electron Green's functions. The expressi on 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 te mperature and to the lowest order in the electron-phonon interaction. Our results show that the suppression of excess noise due to a correla tion 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(omega)/eI(dc) is very sensitive to asymmetry of the tunneling barrier heights. Such a sensitivity is reduced for p honon-assisted processes.