Solid state electronic devices have transformed our lives over the past fifty years: the development of devices like the transistor, integrated circuits and magnetic hard disks have given us a revolution in computing power, portable electronics and the ability to store and handle vast amounts of data. Quantum technologies aim to harness the power of quantum physics to deliver a further revolution in areas such as computing, sensing and communication. The UK is currently making a major investment in the exploitation of quantum science research to deliver a range of quantum technologies - so far this investment has focused on platforms of photonics, cold atoms and trapped ions. The aim of our proposal, Quantum Engineering of Solid-State Technologies, or QUES2T, is to address the capability gap in in quantum solid-state technologies and ensure the UK is in a strong competitive position in some of the most high-impact and scalable quantum technologies. In QUES2T we focus on three solid-state platforms which are well-poised to make significant commercial impact: i) silicon nano-devices, ii) superconducting circuits and iii) diamond-based devices. Each of these materials have demonstrated outstanding properties: silicon can store quantum information for a record-breaking 3 hours, superconducting circuits have been used to make the most complex quantum devices to date, while diamond based magnetometer have a sensitivity to image individual proton spins in a second. We will exploit these properties to develop practical quantum technologies. Importantly, we do not consider these platforms in isolation. A key strength and unique feature of QUES2T is that it not only provides essential infrastructure in each of these three areas but that it brings together a team of people with expertise across these different platforms. This will allow exchange of cross-fertilisation of different disciplines through transfer of expertise and the accelerated development of hybrid technologies that combine the best properties of different materials, to make new detectors, memories, and processors. QUES2T will allow UK researchers and their collaborators to exploit the advantages of developing new quantum devices based on solid state technologies, including easier integration with existing conventional technologies (such as CMOS processors) and reduced timescales to market and manufacturing. The capital infrastructure of QUES2T will establish world-class fabrication capabilities to manufacture high-quality quantum device prototypes out of a range of materials. It will also enable the creation of low-temperature technology test-beds to test the prototypes and develop technology demonstrators. These test-beds will combine a number of essential features, enabling devices to be addressed optically using lasers, with microwave pulses, under low-noise electrical measurements, and all at a hundredth of a degree kelvin. Such systems will be unique UK. To deliver our vision, we have established strong links with academic and industrial partners to exchange the latest technology, expertise and materials. Examples are ultra low-phase noise signal generators with applications in fast high-fidelity qubit control or isotopically pure materials for quantum prototypes in Si and diamond. Industry users working on quantum technologies will be actively encouraged to access the QUES2T infrastructure, such as a state-of-the-art 100 keV electron beam writer to make devices with 10nm features. Many industry partners will also be end users of the technologies that will be developed through QUES2T. Early technologies include scanning probe devices enabling magnetic resonance imaging at the single molecule level and quantum current standards counting electrons one-by-one. On a longer timescale, a fault-tolerant and scalable Si or superconducting based quantum processor, would be form the basis of a new and disruptive industry in computing.

For centuries diamond has been highly sought after for manufacture into gem stones; the demand stems from its exemplary physical properties. Such remarkable characteristics also render diamond a promising host medium for many advanced technology applications. With recent breakthroughs in the manufacture of synthetic diamond substrates, the adoption of diamond into widespread device application is becoming ever more tangible. However, there is an urgent need for a scalable processing framework that can turn this hard, inert material into functional devices. In the course of this fellowship, I will develop a diverse toolkit based around laser fabrication which can fill this void. Through the use of short pulsed lasers and advanced optical techniques, accurate fabrication in three dimensions beneath the surface of diamond becomes possible. Dependent on the laser power and how it is focused into the diamond, different processing regimes are possible. Electrically conductive wires may be printed in 3D running through the diamond, as can optical wires for routing light through the diamond. By reducing the laser power, it is possible to introduce just a single defect in the diamond lattice which can then be used as an information bit for quantum processing. Devices manufactured will include detectors of high energy radiation for use at CERN, 3D arrays of defects for quantum enhanced sensing and 3D photonic structures for manipulation of light. This will deliver a route to commercial diamond technology as well as a set of optical fabrication protocols that are transferable across wide technological areas. The bulk of the work will be carried out at the Department of Engineering Science at the University of Oxford. There will be close collaboration though with partners at the Universities of Manchester, Warwick and Strathclyde, harnessing their unique capabilities to develop a complete photonics system for the creation of advanced technology devices in diamond.

This research proposal is targeted at addressing the challenge of real-time metrology for control of flexible and reconfigurable technological plasma systems. Plasma technologies not only underpin many high-end multi-billion pound manufacturing industries of today, but also are critical elements for the invention of new devices of the future. A new revolution is underway in plasma processing; the 'ivy-bridge' 3-dimensional atomic layer nano-structures of Intel Corp. and new carbon-based supermaterials of Element Six have only just been realised. This opens up new horizons for inventions. Envisaged applications of next-generation plasma processing include manipulation of edge-bonds of single-layer graphene, low power biologically implanted chips as sensors or neuro-motive devices, innovative chemistry applications for biofuel synthesis and realisation of micro-batteries, flexible micro-electronics, fabrication of micro-electromechanical devices, as well as directly using plasmas for medicine, surgery and pharmacy. Realisation of all these critically depends on the development of new adaptable plasma processing techniques. As the industry transforms itself this is an exciting time. One critical bottleneck is the lack of adaptable process control. We propose a novel non-invasive sensor and virtual metrology concept to monitor substrate relevant parameters to enable real-time plasma tuning. This has developed from our pioneering research on the topic and recent discoveries. Our innovative sensor - pulse induced optical emission spectroscopy (PiOES) is analogous to laser induced fluorescence spectroscopy and will instead of a laser utilise a non-intrusive low voltage rapid nanosecond electronic pulse to generate similar excitation conditions in the plasma. Electron impact excitation will create transient excited states and through the subsequent optical fluorescence, and associated temporal fingerprint, distinct atoms and molecules can be identified. The power and sensitivity of the technique originates from exploiting both the energy dynamics as well as the population dynamics in the nonlinear plasma-surface interface (sheath) region. This will allow detection down to atomic layer defects within micron locality. The aim of our research programme is to develop and demonstrate our metrology technique in three extreme working environments: low pressure anisotropic plasma etching, synthetic diamond manufacturing, and atmospheric plasmas for medicine and pharmacy. We will demonstrate this metrology technique in full fabrication reactors and environments. This project is a collaboration between world-leaders in the field: The University of York, The University of Bristol, Intel Corp., Element Six, Andor Technology, Quantemol, Smith and Nephew, Hiden Analytical and Oxford Instruments. An advisory board, including leading members from a diverse range of companies and academia, has been installed to ensure industrial relevance and uptake as the project progresses.

Thermal management and heat dissipation have become the main technological challenges for the next generation of electronic and photonic devices. Heat generated by any electronic device must be effectively dissipated to improve performance, reliability and prevent premature failures. There is an urgent need for novel electronic materials with a high thermal conductivity. Presently there are only a very limited number of cost-effective and reliable high thermal conductivity materials which can be used in electronic devices, including for passive cooling. The ideal material is diamond, with a thermal conductivity as large as 2300 W/mK. However, it is costly to produce, and there is a mismatch between diamond's coefficient of thermal expansion and majority of semiconductors. Copper (~400 W/mK) and its alloys for example with tungsten, and aluminium (~200 W/mK) remain the most widely used materials for heat dissipation in current electronic devices. Boron arsenide (BAs) is a semiconductor with a band gap of ~1.5 eV. Interest in the BAs system has been reignited by recent theoretical predictions that BAs has an ultrahigh thermal conductivity, comparable to that of diamond. In 2018 three groups independently reported the growth of BAs microcrystals with a thermal conductivity close to diamond. It has been demonstrated that BAs-microcrystal cooling substrates allow to exhibit substantially lower hot-spot temperatures in GaN transistors due to their unique phonon band structures and interface matching, beyond those when using diamond and silicon carbide substrates. This illustrates the potential for using BAs in the thermal management of electronics, however, present BAs crystals are only a few mm in size. Furthermore, due to its beneficial electronic properties, BAs is not only attractive for passive cooling of electronics such as GaN, but also by itself a very promising novel material to be transformative for electronic and photovoltaic devices. Now the main challenge in realising the potential of this novel material is to develop a scalable technology of high-quality BAs layers. Boron nitride (BN) exists in several structural polytypes. Hexagonal boron nitride (hBN) polytype, graphite-like, is thermodynamically the most stable phase and presently the most widely explored polytype. The lamellar crystal structure made hBN one of a major 2D material. However, of even greater interest is the much less explored cubic structural polytype of BN - zinc-blende (cBN). cBN does not have a laminar structure and could be more easily integrated with standard semiconductor device heterostructures. Cubic boron nitride is a semiconductor with much larger bandgap energy of ~6.4 eV, which makes it a very important new material for potential deep ultraviolet (DUV) light-emitting and power electronic applications. cBN also has a very good isotropic thermal conductivity and therefore has high potential in heat sink devices. The first cBN bulk microcrystals were recently demonstrated. However, a scalable technology for cBN layers is not yet developed. This project will develop a transformative scalable technology for the boron-based semiconductors, which promise to revolutionize the areas of power electronics and photonics. Boron-based materials, including boron arsenide (BAs), cubic boron nitride (cBN) and highly mismatched BNAs alloy layers, will enable a wide optical range from infrared (IR) to deep ultraviolet (DUV) for photonics and will allow layers with high thermal conductivity. High breakdown fields will allow their applications in power electronics. Our vision is that molecular beam epitaxy (MBE) provides the most promising route to the scalable growth of the cubic boron-based semiconductors. This will be the first project world-wide enabling scalable high thermal conductivity boron-based layers using MBE as main growth method.

The Scottish Doctoral Training Centre in Condensed Matter Physics, known as the CM-DTC, is an EPSRC-funded Centre for Doctoral Training (CDT) addressing the broad field of Condensed Matter Physics (CMP). CMP is a core discipline that underpins many other areas of science, and is one of the Priority Areas for this CDT call. Renewal funding for the CM-DTC will allow five more annual cohorts of PhD students to be recruited, trained and released onto the market. They will be highly educated professionals with a knowledge of the field, in depth and in breadth, that will equip them for future leadership in a variety of academic and industrial careers. Condensed Matter Physics research impacts on many other fields of science including engineering, biophysics, photonics, chemistry, and materials science. It is a significant engine for innovation and drives new technologies. Recent examples include the use of liquid crystals for displays including flat-screen and 3D television, and the use of solid-state or polymeric LEDs for power-saving high-illumination lighting systems. Future examples may involve harnessing the potential of graphene (the world's thinnest and strongest sheet-like material), or the creation of exotic low-temperature materials whose properties may enable the design of radically new types of (quantum) computer with which to solve some of the hardest problems of mathematics. The UK's continued ability to deliver transformative technologies of this character requires highly trained CMP researchers such as those the Centre will produce. The proposed training approach is built on a strong framework of taught lecture courses, with core components and a wide choice of electives. This spans the first two years so that PhD research begins alongside the coursework from the outset. It is complemented by hands-on training in areas such as computer-intensive physics and instrument building (including workshop skills and 3D printing). Some lecture courses are delivered in residential schools but most are videoconferenced live, using the well-established infrastructure of SUPA (the Scottish Universities Physics Alliance). Students meet face to face frequently, often for more than one day, at cohort-building events that emphasise teamwork in science, outreach, transferable skills and careers training. National demand for our graduates is demonstrated by the large number of companies and organisations who have chosen to be formally affiliated with our CDT as Industrial Associates. The range of sectors spanned by these Associates is notable. Some, such as e2v and Oxford Instruments, are scientific consultancies and manufacturers of scientific equipment, whom one would expect to be among our core stakeholders. Less obviously, the list also represents scientific publishers, software houses, companies small and large from the energy sector, large multinationals such as Solvay-Rhodia and Siemens, and finance and patent law firms. This demonstrates a key attraction of our graduates: their high levels of core skills, and a hands-on approach to problem solving. These impart a discipline-hopping ability which more focussed training for specific sectors can complement, but not replace. This breadth is prized by employers in a fast-changing environment where years of vocational training can sometimes be undermined very rapidly by unexpected innovation in an apparently unrelated sector. As the UK builds its technological future by funding new CDTs across a range of priority areas, it is vital to include some that focus on core discipline skills, specifically Condensed Matter Physics, rather than the interdisciplinary or semi-vocational training that features in many other CDTs. As well as complementing those important activities today, our highly trained PhD graduates will be equipped to lay the foundations for the research fields (and perhaps some of the industrial sectors) of tomorrow.