Micro-spectroscopic soft X-ray studies of low-cost epitaxial graphene and adsorbates

点击翻译按钮获取中文摘要

Graphene - the remarkable two-dimensional material whose discoverers were awarded a Nobel prize - may revolutionise the electronics industry. This depends on controlling the electronic properties of the material AND on making such material cheaply. In ordinary three-dimensional materials like silicon, control is achieved by introducing impurities into the material ("doping"). It is not possible to dope graphene conventionally without destroying some of the electronic properties that make it so attractive in the first place. An alternative is "transfer doping" where we place certain molecules on top of the graphene sheet and they add or remove electrons without damaging the sheet's superb electrical properties. We will also need to examine the effects of the substrate that the graphene sheet lies on.In this project we will investigate the electronic structure of graphene on different substrates and with different molecules on top of it. This will be done using a technique called "angle resolved photoemission spectroscopy", or ARPES, in which we knock electrons out of the graphene using soft X-ray photons and calculate their momentum and energy to build up a complete picture of the electronic structure. However, we will be using advanced ARPES systems at major X-ray facilties in France, Italy and elsewhere which are capable of making these measurements on tiny length scales - less than one micrometre. This will enable us to work out changes in the electronic structure of graphene made in a very cheap and simple way in our lab using the same techniques likely to be employed by the electronics industry. Unlike expensive crystalline substrates, our samples are made on cheap metal foils and are not uniform so we need spatial resolution in the ARPES measurement.A key part of our project is building up collaborations with theoretical physicists who will be able to help us understand and predict the changes of electronic properties of our cheap, industrially relevant graphene. Such a predictive ability will be a big step forward in bringing graphene to real-world applications in areas such as information technology, advanced detectors and energy efficiency.