Semiconductors are commonly used in imaging sensors and solar cells, as they can directly convert light into an electrical current. The highest band of electron energies that are fully occupied is known as the valence band while the lowest unfilled energy band is the conduction band. The energy difference between the conduction and valence bands is known as the bandgap. When electrons from the valence band are excited into the conduction band by absorbing light with energy equals to or greater than the bandgap, the change of charges induces an electrical current. Consequently the bandgap is the most important parameter in the design of semiconductor photodetectors. While visible wavelength photodetectors are widely available, detectors for infrared wavelengths are significantly less mature and more costly. Progress in infrared detectors has been hindered by the limited choice of bandgaps currently available. In this work we will introduce a novel approach, by incorporating Bismuth (Bi) atoms into existing semiconductors such as InAs and InGaAs, to achieve a wide range of bandgap energies to detect infrared signals across a correspondingly wide wavelength range. Achieving this will lead to a new range of infrared detectors that can have transformative impact on applications including night vision imaging, medical diagnostic sensors, environmental monitors and for accurate temperature measurements in manufacturing processes. We will also exploit Bi-alloys to engineer a noiseless charge amplification process in photodiodes known as avalanche photodiodes (APDs). When an electron leaves the valence band a vacant state (a hole) is created. Therefore an electron and a hole are created as a pair of charges in semiconductors. Properties of the conduction and valence bands will determine how electrons and holes gain energy from an applied electric field. In materials such as InAs, electrons gain energy at a much faster rate and travel at higher velocity too, when a voltage is applied. Therefore InAs is an excellent material for high speed electronic devices and also for providing internal signal amplification in APDs. When designed appropriately, the energetic electrons in InAs APD ensure that the amplification process, known as impact ionisation, is coherent so that negligible amplification noise is generated. In this work we will incorporate Bi into InAs to alter the valence band such that only electrons will gain significant energy from the electric field. This ability to suppress energetic holes will allow us to design very high gain APD across a wide range of electric field while concomitantly suppressing the noise associated with impact ionisation. By carefully controlling the fraction of Ga and Bi atoms, we will also develop a range of InGaAsBi APDs suitable for detecting a wide range of infrared wavelengths. The proposed research to introduce a new class of Bi-containing infrared detectors and APDs, will be carried out by a carefully assembled team of world leading researchers from Universities of Sheffield and Surrey, in collaboration with the Tyndall National Institute, as well as partners from LAND Instruments, Laser Components and the UK Quantum Technology Hubs in Enhanced Quantum Imaging. Our work will start with a focus on formulating growth conditions (such as temperature and atomic fluxes) to obtain high quality InGaAsBi crystals. Following an intensive crystal growth programme, we will develop procedures to fabricate the grown InGaAsBi semiconductors into devices for a wide range of measurements to extract key material parameters. A model that accurately describes the bandstructure of InGaAsBi will be developed so that we can use them to design high performance infrared detectors and APDs. These newly engineered devices will be evaluated with our industrial partners for applications ranging from temperature measurements in manufacturing to novel imaging techniques using quantum properties of light.

We will establish the primary global manufacturing research hub for Compound Semiconductors that brings together Academic and Industrial researchers. This will capitalize on existing academic expertise in Cardiff, Manchester, Sheffield and UCL and the UK indigenous corporate strength in the key advanced materials technology of Compound Semiconductors. Cardiff, the Compound Semiconductor Centre and the other spoke universities will provide > £100M of additive capital leverage to the Hub, providing European leading facilities for large scale compound semiconductor epitaxial growth, device fabrication and characterisation enabling the most effective translation of research to manufacturing. The hub will operate at the necessary scale and with the necessary reach to change the approach of the UK compound semiconductor research community to one focused on starting from research solutions that can be manufactured. It will do this by providing the necessary tools and expertise and will become the missing exploitation link for the UK compound semiconductor research community. It will be a magnet and the driver for high technology industry and will act as the focal point for Europe's 5th Semiconductor Cluster and the 1st dedicated to compound semiconductors. Partners will include local and UK companies and global organisations. The importance of compound semiconductor technology cannot be overstated. It has underpinned the internet and enabled megatrends such as Smart Phones and Tablets, satellite communications / GPS, Direct Broadcast TV, energy efficient LED lighting, efficient solar power generation, high capacity communication networks, data storage, ground breaking healthcare and biotechnology. Silicon has supported the information society in the 20th century and dominates memory and processor function, but is reaching fundamental limits. Whilst the combination of Silicon and compound semiconductors will produce a second revolution in the information age, they are very different materials with, for example, different fundamental lattice constants and different thermal properties and have different device fabrication requirements. We propose research into large scale Compound Semiconductor manufacturing and in manufacturing integrated Compound Semiconductors on Silicon. The scale of the hub means we can bring together three world leading researchers in the growth of compound semiconductors on Silicon. Each has individually invented different solutions to tackle the silicon / compound semiconductor interface - together they will invent the universal solution. We will solve the scientific challenges in wafer size scale-up, process statistical control and integrated epitaxial growth and processing to facilitate new devices and integrated systems and open up completely new areas of research, only possible with reliable and reproducible fabrication, such as electronically controlled Qubits. We will facilitate the improved communication infrastructure necessary for the connected world and the integrated systems of the Internet of Things. We will produce large area integrated sensor arrays for, e.g. in-process Non-Destructive Testing, further benefiting manufacturing but also improving our safety and security. The key outcomes will be to 1) To radically boost the uptake and application of Compound Semiconductor technology by applying the manufacturing approaches of Silicon to Compound Semiconductors, 2) To exploit the highly advantageous electronic, magnetic, optical and power handling properties of Compound Semiconductors while utilising the cost and scaling advantage of silicon technology where best suited and 3) To generate novel integrated functionality such as sensing, data processing and communication.

Photonics is one of six EU "Key Enabling Technologies. The US recently announced a $200M programme for Integrated Photonics Manufacturing to improve its competiveness. As a UK response, the research proposed here will advance the pervasive technologies for future manufacturing identified in the UK Foresight report on the Future of Manufacturing, improving the manufacturability of optical sensors, functional materials, and energy-efficient growth in the transmission, manipulation and storage of data. Integration is the key to low-cost components and systems. The Hub will address the grand challenge of optimising multiple cross-disciplinary photonic platform technologies to enable integration through developing low-cost fabrication processes. This dominant theme unites the requirements of the UK photonics (and photonics enabled) industry, as confirmed by our consultation with over 40 companies, Catapults, and existing CIMs. Uniquely, following strong UK investment in photonics, we include most of the core photonic platforms available today in our Hub proposal that exploits clean room facilities valued at £200M. Research will focus on both emerging technologies having greatest potential impact on industry, and long-standing challenges in existing photonics technology where current manufacturing processes have hindered industrial uptake. Platforms will include: Metamaterials: One of the challenges in metamaterials is to develop processes for low-cost and high-throughput manufacturing. Advanced metamaterials produced in laboratories depend on slow, expensive production processes such as electron beam writing and are difficult to produce in large sizes or quantities. To secure industrial take up across a wide variety of practical applications, manufacturing methods that allow nanostructure patterning across large areas are required. Southampton hosts a leading metamaterials group led by Prof Zheludev and is well positioned to leverage current/future EPSRC research investments, as well as its leading intellectual property position in metamaterials. High-performance special optical fibres: Although fibres in the UV and mid-IR spectral range have been made, few are currently commercial owing to issues with reliability, performance, integration and manufacturability. This platform will address the manufacturing scalability of special fibres for UV, mid-IR and for ultrahigh power sources, as requested by current industrial partners. Integration with III-V sources and packaging issues will also be addressed, as requested by companies exploiting special fibres in laser-based applications. In the more conventional near-infrared wavelength regime, we will focus on designs and processes to make lasers and systems cheaper, more efficient and more reliable. Integrated Silicon Photonics: has made major advances in the functionality that has been demonstrated at the chip level. Arguably, it is the only platform that potentially offers full integration of all the key components required for optical circuit functionality at low cost, which is no doubt why the manufacturing giant, Intel, has invested so much. The key challenge remains to integrate silicon with optical fibre devices, III-V light sources and the key components of wafer-level manufacture such as on line test and measurement. The Hub includes the leading UK group in silicon photonics led by Prof Graham Reed. III-V devices: Significant advances have been made in extending the range of III-V light sources to the mid-IR wavelength region, but key to maximise their impact is to enable their integration with optical fibres and other photonics platforms, by simultaneous optimisation of the III-V and surrounding technologies. A preliminary mapping of industrial needs has shown that integration with metamaterial components optimised for mid-IR would be highly desirable. Sheffield hosts the EPSRC III-V Centre and adds a powerful light emitting dimension to the Hub.