Effect of screening on shot noise in diffusive mesoscopic conductors

Abstract

Shot noise in diffusive mesoscopic conductors, at finite observation frequencies $ω$ (comparable to the reciprocal Thouless time $τ_T^{-1}$), is analyzed with an account of screening. At low frequencies, the well-known result $S_I(ω)=2eI/3$ is recovered. This result is valid at arbitrary $ωτ_T$ for wide conductors longer than the screening length. However, at least for two very different systems, namely, wide and short conductors, and thin conductors over a close ground plane, noise approaches a different fundamental level, $S_I(ω) = eI$, at $ωτ_T\gg 1$.