Orbital Tuning of Tunnel Coupling in InAs/InP Nanowire Quantum Dots

Abstract

We report results on the control of barrier transparency in InAs/InP nanowire quantum dots via the electrostatic control of the device electron states. Recent works demonstrated that barrier transparency in this class of devices displays a general trend just depending on the total orbital energy of the trapped electrons. We show that a qualitatively different regime is observed at relatively low filling numbers, where tunneling rates are rather controlled by the axial configuration of the electron orbital. Transmission rates versus filling are further modified by acting on the radial configuration of the orbitals by means of electrostatic gating, and the barrier transparency for the various orbitals is found to evolve as expected from numerical simulations. The possibility to exploit this mechanism to achieve a controlled continuous tuning of the tunneling rate of an individual Coulomb blockade resonance is discussed.

Surface Nano-Patterning for the Bottom-Up Growth of III-V Semiconductor Nanowire Ordered Arrays

“…Among all the successful applications reported in the literature, here we name just a few examples in order to provide an idea of the potential of these systems both in research and technology. Single electron transistors made of axial InAs/InP nanowire heterostructures (quantum dots) [ 47 , 48 ], axial and radial NW heterostructures applied to solar cells [ 16 ] and other core-shell devices [ 49 , 50 ], light emitting diodes [ 51 ], lasers [ 52 ], photodetectors [ 53 , 54 ], thermoelectric devices [ 55 , 56 ], sensors [ 57 ], spin based quantum systems [ 58 , 59 , 60 ], topological qubits based on Majorana physics [ 61 , 62 ], and many others have been reported. Moreover, homogeneous nanowires and heterostructured nanowires are widely employed as test-bed platforms for investigating basic physics phenomena, including properties of materials [ 63 , 64 , 65 ], ion gating mechanisms [ 66 , 67 , 68 , 69 ], advanced quantum concepts [ 45 ], hybrid semiconductor-superconductors systems [ 70 , 71 ], etc.…”

“…Of course, any approach to nanowire growth based on a metal catalyst may pose a drawback related to the introduction of metal contaminations during the growth process [ 107 , 108 ]. While this may represent a minor or even negligible issue for the demonstration of prototypical nanoelectronic devices based on individual nanowires [ 47 , 56 ], at a time it can represent a major obstacle for the integration of semiconductor nanowires with silicon technologies, because the use of gold introduces deep traps in silicon, thus deteriorating, for instance, the optoelectronic properties of the devices [ 109 , 110 ]. To bypass this potential obstacle, many efforts were devoted to the development of alternative growth schemes, avoiding the use of foreign metal seed particles as catalysts, and at least two classes of methods were proposed as alternatives to metal-catalyzed growth, namely, self-assisted growth and catalyst-free growth.…”

Characterization of electrostatically defined bottom-heated InAs nanowire quantum dot systems

“…Nanowire-based, heated TE QD devices are commonly built with epitaxially-defined InAs/InP QD structures [18,20,28]. Such epitaxially defined QD systems offer large single-particle energies and symmetric tunnel couplings at the cost of a static barrier structure and complex control over the tunnel couplings [29]. TE devices further require a heater with a large, local heating efficiency, controlled and continuous tunability of the temperature gradient and compatibility with the QD gating technique [30].…”

Quantum-Dot Single-Electron Transistors as Thermoelectric Quantum Detectors at Terahertz Frequencies

“…Here, we conceive and devise quantum-dot millimeter-wave nanodetectors employing InAs/InAsP QD nanowires (NWs) that, thanks to the small effective mass and favorable Fermi level pinning 30,31 , give rise to localized QDs characterized by large charging energy 31,32 .…”

“…The achieved performances, combined with the extreme versatility of the QD-NW platform in terms of geometry and chemical composition, and with the intrinsically broadband and zero-bias nature of the PTE detection mechanism, unveiled through the choice of the impinging frequency -NW QD geometry combination, leave room for substantial improvements of the proposed quantum detection concept. For example, we envision that an optimization strategy for the PTE conversion shall proceed towards the reduction of the tunnel coupling between the dot and the leads 31 , the engineering of the energy levels spacing and the exploitation of quantum phenomena, e.g. Kondo effect 54 , in search of a balance between This is the authors' version of the article submitted to Nano Letters and accepted for publication https://doi.org/10.1021/acs.nanolett.1c02022 detector sensitivity and speed (see Supporting Information file).…”