Few-electron quantum dots in III-V ternary alloys: role of fluctuations

TL;DR

This paper investigates electron transport in quantum dots formed in III-V ternary alloys, revealing effects like Coulomb blockade, photon-assisted tunneling, and complex multi-dot formations due to potential fluctuations.

Contribution

It provides experimental insights into how potential fluctuations influence quantum dot formation and electron transport in InGaAs/InP and InAsP/InP structures.

Findings

Observation of Coulomb-blockade diamonds in few-electron regime

Detection of photon-assisted tunneling peaks under microwave irradiation

Formation of multi-dot systems due to potential fluctuations

Abstract

We study experimentally the electron transport properties of gated quantum dots formed in InGaAs/InP and InAsP/InP quantum well structures grown by chemical-beam epitaxy. For the case of the InGaAs quantum well, quantum dots form directly underneath narrow gate electrodes due to potential fluctuations. We measure the Coulomb-blockade diamonds in the few-electron regime of a single quantum dot and observe photon-assisted tunneling peaks under microwave irradiation. A singlet-triplet transition at high magnetic field and Coulomb-blockade effects in the quantum Hall regime are also observed. For the InAsP quantum well, an incidental triple quantum dot forms also due to potential fluctuations within a single dot layout. Tunable quadruple points are observed via transport measurements.