Shell structure and electron-electron interaction in self-assembled InAs quantum dots

TL;DR

This study uses far-infrared and capacitance spectroscopy to explore electron interactions and shell structures in self-assembled InAs quantum dots, revealing complex excitation spectra and deviations from classical Coulomb blockade patterns.

Contribution

It provides new insights into electron-electron interactions and shell effects in InAs quantum dots with non-parabolic confinement, expanding understanding beyond traditional models.

Findings

Rich excitation spectrum at n=3 electrons

Distinct charging energy patterns due to shell structure

Deviation from monotonic Coulomb blockade behavior

Abstract

Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode spectrum is observed when the lowest s - states are filled, we find a rich excitation spectrum for n=3, which reflects the importance of electron-electron interaction in the present, strongly non-parabolic confining potential. From capacitance spectroscopy we find that the electronic shell structure in our dots gives rise to a distinct pattern in the charging energies which strongly deviates from the monotonic behavior of the Coulomb blockade found in mesoscopic or metallic structures.