An efficient, practical and cost-effective means for directly converting heat into electricity is a very appealing concept. In principle, thermo-photovoltaic (TPV) cells could form the critical component of various systems for generating electricity from different types of heat sources including combustion processes, concentrated sunlight, waste process heat, and radio isotopes. This opens up a wide variety of possibilities for technology uptake and so TPV systems can be envisaged for use in applications ranging from small power supplies to replace batteries, to large scale co-generation of electricity. However, existing TPV cells are based on GaSb and are spectrally matched to heat sources at temperatures of ~1800 oC which limits their practical implementation and widespread uptake. In this project we shall build on existing UK based world class III-V semiconductor materials expertise to fabricate novel low bandgap TPV arrays on inexpensive GaAs substrates, capable of efficient electricity generation from thermal waste heat sources in the range 500-1000 0C commonly encountered in industrial processes. The project will demonstrate the next step towards fabrication of large area TPV arrays essential for the commercial viability of TPV heat recovery, and will enable their widespread implementation in a wide range of high energy consumption industries such as glass, steel and cement manufacture, oil/gas and energy generation.

N/A - see case for support

An efficient, practical and cost-effective means for directly converting heat into electricity is a very appealing concept. In principle, thermo-photovoltaic (TPV) cells could form the critical component of various systems for generating electricity from different types of heat sources including combustion processes, concentrated sunlight, waste process heat, and radio isotopes. This opens up a wide variety of possibilities for technology uptake and so TPV systems can be envisaged for use in applications ranging from small power supplies to replace batteries, to large scale co-generation of electricity. However, existing TPV cells are based on GaSb and are spectrally matched to heat sources at temperatures of ~1800 oC which limits their practical implementation and widespread uptake. GaInAsSb TPV cells with bandgap 0.53 eV have exhibited excellent performance with internal quantum efficiency near 95%. But, currently these are lattice-matched on GaSb substrates making them too expensive for practical implementation except in specialist high value or space applications. TPV development on larger format GaAs substrates will enable effective technology uptake through cheaper volume manufacturing of TPV cells. Consequently, there is a need to transfer the GaInAsSb cell architecture to GaAs. In this project we shall build on existing UK based world class III-V semiconductor materials expertise to fabricate novel low bandgap InGaAsSb TPV arrays on inexpensive GaAs substrates, capable of efficient electricity generation from thermal waste heat sources in the range 500-1500 oC commonly encountered in industrial processes. These monolithic arrays will be validated on-site together with our industry partners at Pilkington and MPIUK (Tata steel). The project will demonstrate the next step towards fabrication of large area TPV arrays essential for the commercial viability of TPV heat recovery, and will enable their widespread implementation in a wide range of high energy consumption industries such as glass, steel and cement manufacture, oil/gas and energy generation.

AlGaN/GaN high electron mobility transistors (HEMTs) are a key enabling technology for future power conditioning applications in the low carbon economy, and for high efficiency military and civilian microwave systems. GaN-on-Si is highly attractive as a low cost, medium performance technology platform which has been proved to be usable even up to the W-band. The main down-sides of Si are the low bandgap and hence resistive lossy substrate especially at modest elevated temperatures, the vulnerability of the Si to unintentional doping with gallium during epitaxy causing RF losses, and the somewhat restricted power handling resulting from the relatively low thermal conductivity of the Si compared to the 4" SiC growth substrates currently used. However the cost benefits are dramatic allowing 6" or even 8" high volume wafer processing. 6" GaN-on-Si epitaxy is already available driven by the emerging GaN-on-Si power switch market, however it is optimised for high voltage, switched-mode operation. Improved RF power amplifier (PA) efficiency using GaN-on-Si, which is the focus of this proposal, would reduce the transistor temperature rise, reduce the substrate losses and deliver a low-cost high-performance technology as it would reduce the transistor temperature rise and reduce the substrate losses. The advance that is required is an optimised RF specific GaN-on-Si transistor architecture, which requires detailed understanding of electronic traps introduced into the GaN buffer of these devices by iron, carbon and carbon/iron co-doping, which is presently lacking. The key aim of this proposal is to control and model the device capacitances and conductances using novel epitaxial design of the GaN buffer, as this is key to delivering improved efficiency, gain and linearity in RF amplifiers.

The assessment of human health from analysis of blood samples is one of the most widespread medical diagnostic procedures; with thousands of patients providing samples every day in hundreds of clinics and surgeries across the UK. However, it remains a slow process because samples have to be sent to a limited number of specialist central services in health trusts, with a turn-around of days between sample acquisition and assessment delivery. It is expensive, both in terms of direct cost of the analysis and downstream costs due to deterioration of patient health as a result of the time delay in accessing results. We propose a capillary driven, microscale disposable chip instrument for non-technical users that provides the established and understood diagnostic parameters. The basic device will consist of lasers and detectors integrated around a fluid channel to facilitate counting, scattering and wavelength dependent absorption measurements. This will differentiate red blood cells from white blood cells, discriminate between the main white blood cell types - monocyte, lymphocyte, neutrophil and granulocyte - and provide cell counts of these sub groups. Stage 2 builds on the same technology platform to enhance sensitivity and add functionality by making the cell under test an active part of the laser thus maximising light / cell interaction. In stage 3 we will label cells with fluorescent dye attached to metal particles (provided by Keyes group) and increase the absorption of particular cells, by up to 6 orders of magnitude, and also access fluorescent lifetime measurements (using an approach we have patented) allowing the analysis of cell function as well as cell discrimination. We have blood analysis expertise within the project to maximise the benefits of stage 1 and co-workers focussed on cell cycle and anti-cancer research will interact and maximise the benefits of the device that goes well beyond current blood test capability. The microscale system we will develop offers a number of advantages: Micro scaling reduces the volume of blood required changing the way blood-based diagnostics are used. Immediate and quasi-continuous monitoring of the haematological state is feasible and can be used in acute situations such as surgery or child birth. This also offers, with further development, a realistic route to continuous monitoring during everyday life. Semiconductor micro fabrication provides the route to mass manufacture of low cost systems. Shifts the cost of blood testing from technician to test kit and introduces a distributed cost model (pay per kit) rather than a single, major capital investment. Allows disposable chip format and provides uniformity and repeatability, contributing to the removal of the need for specialist operator - use at point of care, e.g. developing world. We will achieve all this by exploiting the properties of a quantum dot semiconductor system that we have developed and which provides particular advantages for integration and for laser based sensing at relevant wavelengths (a major one being the sensitivity to small changes in optical loss). In addition to the significant medical benefits resulting from the ability to widely deploy, low cost and enhanced clinical functionality devices we also see a significant commercial benefit to the UK, with an identified UK manufacturing supply chain. The project brings together a wide range of complementary experience, including semiconductor device design, fabrication and characterisation, microfluidics, systems analysis and data handling, blood analysis and cytometry and biophotonics and clinical validation.