Project

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Quantum structures in nanowires: physical properties on demand by hydrogen irradiation

Applicant De Luca Marta
Number 179801
Funding scheme Ambizione
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.02.2019 - 31.01.2023
Approved amount 928'295.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Material Sciences

Keywords (9)

Photonics; Magnetic states; Raman spectroscopy; Thermoelectrics; Hydrogen irradiation; Quantum confinement; Semiconductor nanowires; Photoluminescence spectroscopy; Single photon emitters

Lay Summary (French)

Lead
Les nanofils semi-conducteurs sont des cristaux filamentaires de diamètres nanométriques. La création de structures quantiques complexes dans des nanofils, commes des points quantiques, des disques quantiques et des anneaux quantiques, est utile pour le développement de technologies quantiques. Ces structures sont généralement créées lors de la croissance des nanofils, alors qu’elles seront créées après la croissance dans ce projet, principalement par irradiation à l’hydrogène.
Lay summary

Contenu et objectifs du travail de recherche

Le premier objectif du projet est d'étudier les effets de l'irradiation à l'hydrogène sur les propriétés électroniques et du réseau cristallin de certains nanofils III-V, en termes de passivation de surface et de réglage de la bande interdite aussi.

Le deuxième objectif du projet est d'utiliser les effets de l'hydrogène pour réaliser des structures quantiques avec la position contrôlées dans des nanofils et avec des propriétés pour des applications spécifiques en photonique, thermoélectrique et magnétique.

 

Contexte scientifique et social du projet de recherche

Le contrôle des propriétés des semi-conducteurs par incorporation d'hydrogène, très connu et largement utilisé dans les matériaux à trois dimensions, sera, pour la première fois avec ce projet, appliqué aux matériaux nanométriques, en particulier aux nanofils. Cela aura un impact sur le domaine de l'énergie durable, car cela permettra d'améliorer l'efficacité de la récupération de la chaleur perdue. De plus, elle aura un impact sur le domaine de l'informatique quantique et de la communication, car le contrôle de la position de l'émetteur imbriqué dans le guide d'ondes à nanofil et ses propriétés versatiles et réinscriptibles constituent une avancée par rapport aux structures photoniques similaires basées sur des sources lumineuses traditionnels auto-assemblées.

Direct link to Lay Summary Last update: 03.12.2018

Responsible applicant and co-applicants

Employees

Abstract

Nanowires (NWs) are filamentary crystals with diameters of tens of nanometers and several microns in length. The great interest attracted by semiconductor NWs has been triggered by the growing demand for compact and powerful nanoscale devices, where NWs may act as both interconnects and functionalized components. A lot of emphasis in today research in NWs is put on the engineering of complex quantum structures in NWs, for they encode new functionalities and/or enhance existing performances. This project aims at developing unexplored strategies for embedding site-controlled quantum structures in III-V NWs and at finding fast and effective routes to engineer the physical properties of NWs. The pursued routes will involve mainly post-growth hydrogen implantation, thus allowing to achieve different NW properties on demand with no need to change and re-optimize NW growth conditions. Remarkably, the changes in the NW properties will be reversible, as hydrogen can be removed by thermal or laser annealing.Hydrogen is a ubiquitous, highly mobile, and reactive impurity able to passivate most deep and shallow defects purposely or accidentally embedded in semiconductor crystals, and it is present in most steps of semiconductor growth and device processing. In this project, controlled low-energy H+ incorporation will be performed on single NWs and large NW arrays. Among all hydrogen effects, two striking effects well known for bulk samples will be investigated and engineered in the field of NWs: the band gap opening in InN and In-rich InGaN, and the passivation of N atoms in dilute nitrides III-N-V semiconductors such as GaAsN and GaPN. The unique growth environment offered by NWs will allow to benefit from a much greater flexibility with respect to conventional, planar, epitaxial growth, owing to the seamlessly enhanced ability of NWs to accommodate elastic strain and to host even lattice-mismatched material combinations.A variety of quantum structures in NWs will be achieved within this project, mostly but not only by using hydrogenation: quantum dots, quantum wires, quantum rings, quantum well tubes, and quantum wells/disks. The structural characterization of the NWs will be coupled to optical spectroscopy techniques (inelastic light scattering and photoluminescence), also under intense magnetic fields and in a time-resolved regime. The experimental studies will be complemented by a robust theoretical support. In this way, a full picture of the electronic, optical, magnetic, and thermal properties of the quantum structures in NWs will be achieved and controllably tuned.The strength of the proposed approach will be proven by obtaining NWs with desired photonic, thermoelectric, and magnetic properties: in quantum rings and tubes, magnetic states that should appear due to the circular symmetry of their carrier wavefunction will be probed; in quantum dots deterministically positioned in NWs, single photon emission and enhanced light extraction will be investigated in prototypical light emitting devices; in NWs with embedded (non-)periodic superlattices of quantum dots and quantum wells, an enhancement of the thermoelectric power factor and thus of the thermoelectric figure of merit will be pursued. In this project, fundamental scientific investigation and technological applications will be strongly entangled and benefit from each other, as many advanced functionalities are deeply rooted in the way physical laws work in the nanoscale realm.
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