AMORPHOUS CHALCOGENIDE-BASED OPTOELECTRONIC PLATFORM FOR NEXT-GENERATION OPTOELECTRONIC TECHNOLOGIES

Materials discovery, development and modification has been a key factor in developing the world we live in. The study of materials which exhibit electrical or optical properties has played a major role in enabling all of modern technology and in particular electronics, computing and communications. As these technologies have been developed existing materials have also been modified and pushed close to their limits of what is technical feasible. An example of this is the advances made in silicon (Si) based microelectronics which has led to speed, which relates to power of processing, becoming critical, with a reduction in the size of the microelectronics used to achieve this. This approach is ultimately limited as sizes reduce; thus alternative methods must be sought. Optical communication and data transfer is widely known as being much quicker as information can be moved at the speed of light. However, whenever it interacts with electronics, such as when broadband optical fibre is connected to a computer the data transfer and processing must slow down to the speed of the microelectronic processors. There is a strong desire and compelling argument therefore to develop an 'optoelectronic' technology which is a hybrid of the optical and electronic systems but without the current limitations imposed by the two current technologies working independently. This proposal will seek to apply one of the most developed materials modification tools that is fundamental to modern microelectronics, ion-implantation, to a class of materials that show unique potential for enabling future optoelectronic technologies. These materials, known as chalcogenides, are already widely used in applications such as photovoltaics (solar cells), memory (e.g. DVDs), and advanced optical devices (e.g. lasers). Currently however they are used solely as either electronic materials or optical materials, with different types of chalcogenides used for each. Their properties that allow use in these separate application types gives them the potential to be developed so that the excellent optical properties of one material can be combined with the excellent electronic properties of another and vice versa. One of the reasons that this has yet to be done is that it has proved to be extremely difficult to modify their electronic properties during the material preparation which typically involves melting at high temperatures. Anything that is added to the materials, referred to as doping, is ineffective under these conditions due to the ability of the material to reorder itself whilst melted to cancel out the desired effect. In this programme of work, we will modify the properties by introducing dopants into the chalcogenide materials below their melt temperature, thus not allowing the material to reorder. This will be undertaken using ion-implantation which allows precise control of the type of impurity introduced. As a result of this work, we will develop for the first time an understanding of how these unique materials can be modified in a controlled way. We will then use this to develop better models of the origin of the materials' electronic and optical properties which will allow us to develop optimised materials. We will also develop prototype devices that will lead the way to the development of a truly optoelectronic technology. This programme will establish the UK as leaders in this field and therefore directly contribute to the continuing growth of the knowledge economy. We will train the next generation of scientists and engineers in state-of-the-art techniques to ensure that the UK maintains the expertise base required for this, aim to ensure the impact of this work is maximised and accelerated where possible, and communicate the results widely including to all stakeholders in this research.

The primary beneficiaries of this project will be the photonics (including fibre) and micro-electronics fields and the industries they support. This is a vast market; worldwide microelectronics production was 200 billion euros in 2006. Of this, the UK accounts for a production volume of 5.2 billion euros, which corresponds to 12% of the European volume, and 2.3% of the world market. Results of this project are expected to result in considerable interest; both academically and industrially on a local and international scale. Immediate beneficiaries of this research will be the research community, as our scientific results are disseminated to those most closely aligned with our early scientific tasks. The new functionality of the materials we develop will stimulate interest in further electrical and optical applications of chalcogenides. Overall, our work forms an important component of the EPSRC's Grand Challenge in Microelectronics entitled Performance Driven Design For Next Generation Of Chip Design . Chalcogenide glasses are already in use for thin film and fibre waveguides, switching, light emission and amplification while electronic applications, such as phase change memory, are leading the way forward in the microelectronics field. We therefore believe that industrial beneficiaries will follow within the time scale of the project. Our extensive contacts with industry, spin-offs and defence organisations are to be a significant aspect of our exploitation plan and will also allow us to develop new and closer links with industry. Clear industrial interest is reinforced by the involvement of one of the leading international experts in the field of applications of ion-implantation. Dr Jonathan England (Senior Technologist, Varian Semiconductor Equipment Associates - VSEA) has agreed to undertake the role of project mentor with VSEA contributing his time at no cost to the project. With extensive international experience in high-technology development and industrial end-user interaction he will be a significant asset to the programme and enhance its industrial impact. Indeed, many of the device goals, which include new LED's, photodiodes, photovoltaic cells, optical amplifiers, switches and logic gates and memory cells are of great interest to large electronics companies such as Intel, Philips, Siemens and Toshiba, all of which work with VSEA. As is clear from their track record and publications, all the investigators collaborate extensively with a wide range of international academics. In addition to VSEA, all the investigators have well established links with leading international companies which include BAe Systems, Qinetiq, Ilika Technologies Ltd, Gooch and Housego PLC and IBM. Through the dissemination activities of this project, we expect that number and range of collaborations will be enhanced. Liaison within Europe and the UK via new and existing academic and industrial collaborations enabling further research and development activities related to our work will be pursued via European funding agencies, the EPSRC and the TSB. Similarly our extensive international collaborations will be utilised thus enabling the impact of the work undertaken to be world-reaching. Results of the research will be exploited through our Research Support Services (ORC), Research & Enterprise Support (Surrey) and Cambridge Enterprise (Cambridge), who provide valuable commercial resources and also ensure that exploitation is managed in a professional and ethical fashion. Enterprise at Cambridge University is centred on Europe's oldest and largest science parks while both Surrey and Southampton work closely with the SETsquared Partnership, a successful enterprise and entrepreneurship collaboration. We will exploit the results of this work through the development of new spin out companies, liscensing, joint ventures or industry-led deals using proper commercial channels through our Universities.