Highly symmetric and tunable tunnel couplings in InAs/InP nanowire heterostructure quantum dots

Abstract

We present a comprehensive electrical characterization of an InAs/InP nanowire heterostructure, comprising two InP barriers forming a quantum dot (QD), two adjacent lead segments (LSs) and two metallic contacts, and demonstrate how to extract valuable quantitative information of the QD. The QD shows very regular Coulomb blockade (CB) resonances over a large gate voltage range. By analyzing the resonance line shapes, we map the evolution of the tunnel couplings from the few to the many electron regime, with electrically tunable tunnel couplings from <1 µeV to >600 µeV, and a transition from the temperature to the lifetime broadened regime. The InP segments form tunnel barriers with almost fully symmetric tunnel couplings and a barrier height of ∼ 350 meV. All of these findings can be understood in great detail based on the deterministic material composition and geometry. Our results demonstrate that integrated InAs/InP QDs provide a promising platform for electron tunneling spectroscopy in InAs nanowires, which can readily be contacted by a variety of superconducting materials to investigate subgap states in proximitized NW regions, or be used to characterize thermoelectric nanoscale devices in the quantum regime.

Controlled Quantum Dot Formation in Atomically Engineered Graphene Nanoribbon Field-Effect Transistors

“…4b), we can observe partially overlapping diamonds together with the absence of a crossing point at V g =-35 V, suggesting that two or more GNRs contribute to the transport 27,28 . In semiconducting quantum dots formed in systems such as 2DEGs, top-down patterned graphene or carbon nanotubes, the addition energies are typically <10meV, and several Coulomb diamonds can be observed [29][30][31] .…”

Probing proximity induced superconductivity in InAs nanowire using built-in barriers

“…Previous studies have shown that the barriers are atomically sharp, and their width can be controlled with the precision of a single atomic layer [21]. Using two of these barriers quantum dots were formed [22], which were used to study coupling asymmetries in a dot [23], the Stark effect [24][25][26] or thermal transport in quantum dots [27][28][29]. However, no studies have investigated how well these barriers can be used as a spectroscopy tool for superconducting bound states.…”