FUNCTIONAL NANOWIRES, NANOWIRE HETEROSTRUCTURES AND THREE-DIMENSIONAL NANOWIRE NETWORKS
Lead Research Organisation:
University College London
Department Name: London Centre for Nanotechnology
Abstract
The ITRS roadmap for the semiconductor industry has identified semiconducting nanowires as a possible route by whichthe size-scaling of Moore's Law can be extended to yet smaller dimensions. Nanowires could be used both as the logicelements and the memory elements in a future semiconductor technology with device dimensions below 10 nm. The fieldof nanowire research is therefore particularly active at present and can be expected to deliver real applications in themedium to long term.In this fellowship I will address two key issues which must be resolved if nanowire applications are to make an impact inthe electronics sector:(i) How can nanowires be interconnected to form useful circuits?(ii) What unique functional properties can be engineered into nanowires that can be exploited in applications?Experiments to address the first of these issues will focus on using organic scaffold deposition (OSD) for growth of three-dimensional metallic nanowire networks. In particular we will study the growth of magnetic nanowires using OSD with the ultimate aim of creating a three-dimensional magnetic storage medium for high-density computer memory applications.Experiments to address the second issue will concentrate on semiconducting and superconducting nanowires. For semiconducting nanowires we will use the established nanoparticle-seeded molecular beam epitaxy (NS-MBE) technique and extend it to a variety of III-V and II-VI materials. Using NS-MBE we will be able to modulate the properties of the nanowire along its length simply by changing the precursor material during growth. (This technique has already been demonstrated to result in atomically sharp materials interfaces in the InP/InAs system.) NS-MBE therefore gives us a toolkit for studying the role of reduced dimensionality on a number of functional materials and heterostructures, including (for example) dilute magnetic semiconductors and heterostructure photonic devices.Superconducting nanowires will be grown using focussed-ion-beam and OSD techniques. These nanowires, which display a range of new physical phenomena, will be studied for applications as single photon detectors for use in infra-red quantum key distribution systems and as quantum current standards.
People |
ORCID iD |
Paul Warburton (Principal Investigator) |
Publications
Albash T
(2015)
Consistency tests of classical and quantum models for a quantum annealer
in Physical Review A
Burnett J
(2017)
Low-Loss Superconducting Nanowire Circuits Using a Neon Focused Ion Beam
in Physical Review Applied
Burnett J
(2016)
Embedding NbN Nanowires Into Quantum Circuits With a Neon Focused Ion Beam
in IEEE Transactions on Applied Superconductivity
Chancellor N
(2017)
Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture
in npj Quantum Information
Chancellor N
(2016)
A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera Graph
Chancellor N
(2016)
Maximum-Entropy Inference with a Programmable Annealer.
in Scientific reports
Chancellor N
(2015)
Maximum-Entropy Inference with a Programmable Annealer
Chancellor, Nicholas
(2016)
Maximum-Entropy Inference with a Programmable Annealer
Coke M
(2017)
Electron confinement at diffuse ZnMgO/ZnO interfaces
in APL Materials
Description | We have developed a number of techniques for growth and characterisation of three types of functional nanowires and nanowire heterostructures: (i) InAs and InAsSb III-V semiconductor nanowires; (ii) ZnO and ZnMgO II-VI semiconductor nanowires; (iii) superconducting nanowires. For the III-V nanowires we focussed on growing without the use of a heterocatalyst on silicon substrates. We developed protocols using in situ argon miling for minimising the contact resistance between Ohmic metallic contacts and the nanowires. By incorporating Sb in the growth we were able to control the defect density in the InAsSb nanowires, thereby maximising the electron mobility. This is turn enabled us to measure quantum coherent transport in the nanowires - specifically universal conductance fluctuations. Our work on II-VI nanowires focussed on controlling the growth orientation during oxygen-plasma-assisted MBE. We have grown ZnO-ZnMgO core-shell heterostrcuture nanowires with the polar axis oriented parallel to the growth vector. For optimum confinement however the polar axis should be oriented normal to the growth vector. We have therefore developed a growth technique for ZnO nanostructures where the latter morphology pertains. We have developed two new methods for characterising defects in ZnO nanowires: scanning transmission electron-microscopy cathodoluminescence and current-mode deep-level transient spectroscopy. Our work on superconducting nanowires has focussed on their application as coherent non-linear elements in quantum circuits. We have shown how to use neon focussed-ion-beam (FIB) to embed NbN nanowires in superconducting microwave resonators without suppressing the quality factor of the resonance. We have extended this to superconducting loops incorporating Nb nanowires - here a magnetic flux applied to the loop enables the resonant frequency to be tuned. We have also used gallium FIB to deposit superconducting tungsten-carbide nanowires in three-dimensional geometries. These were used to create a free-standing pick-up loop for a nanoSQUID magnetic sensor. |
Exploitation Route | New materials for high-speed electronics and sensors. New devices for quantum electronics. |
Sectors | Digital/Communication/Information Technologies (including Software),Electronics |
Description | NPL |
Organisation | National Physical Laboratory |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Scientific research collaboration |
Collaborator Contribution | Scientific research collaboration |
Impact | NPL are formal partners in UCL's EPSRC CDT in Delivering Quantum Technologies |
Description | USC |
Organisation | University of Southern California |
Country | United States |
Sector | Academic/University |
PI Contribution | Collaboration on adiabatic quantum annealing |
Collaborator Contribution | Access to quantum annealing machine; theory support |
Impact | publications conference presentations patent application |
Start Year | 2013 |