Fluctuation of Conductance Peak Spacings in Large Semiconductor Quantum Dots

TL;DR

This paper investigates the fluctuations in Coulomb blockade peak spacings in large semiconductor quantum dots, revealing a distribution with a peak at small spacings and explaining peak behavior under magnetic fields.

Contribution

It introduces a model based on electrostatics of multiple electron islands with random couplings, explaining peak spacing fluctuations and magnetic field effects in large quantum dots.

Findings

Peak spacing distribution peaks at small values

Model explains closely spaced Coulomb blockade peaks

Qualitative behavior of peak positions under magnetic field

Abstract

Fluctuation of Coulomb blockade peak spacings in large two-dimensional semiconductor quantum dots are studied within a model based on the electrostatics of several electron islands among which there are random inductive and capacitive couplings. Each island can accommodate electrons on quantum orbitals whose energies depend also on an external magnetic field. In contrast with a single island quantum dot, where the spacing distribution is close to Gaussian, here the distribution has a peak at small spacing value. The fluctuations are mainly due to charging effects. The model can explain the occasional occurrence of couples or even triples of closely spaced Coulomb blockade peaks, as well as the qualitative behavior of peak positions with the applied magnetic field.