Drastic Reduction of Shot Noise in Semiconductor Superlattices

TL;DR

This paper experimentally demonstrates significant shot noise reduction in semiconductor superlattices, showing that strong coupling reduces noise below Poissonian levels, while weak coupling or high electric fields restore Poissonian noise.

Contribution

It provides new experimental evidence of shot noise behavior in superlattices, highlighting the dependence on coupling strength and electric field, which existing theories do not fully explain.

Findings

Shot noise is reduced to about 1/3 of Poissonian noise in strongly coupled superlattices.

Weak coupling or strong electric fields restore Poissonian shot noise levels.

Experimental results challenge existing theoretical models for shot noise in superlattices.

Abstract

We have found experimentally that the shot noise of the tunneling current $I$ through an undoped semiconductor superlattice is reduced with respect to the Poissonian noise value $2eI$, and that the noise approaches 1/3 of that value in superlattices whose quantum wells are strongly coupled. On the other hand, when the coupling is weak or when a strong electric field is applied to the superlattice the noise becomes Poissonian. Although our results are qualitatively consistent with existing theories for one-dimensional mulitple barriers, the theories cannot account for the dependence of the noise on superlattice parameters that we have observed.