Unveiling electron motion at surfaces and interfaces on ultrashort length and ultrafast time scales

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Semiconductor devices are becoming an increasingly important part of modern life. Smaller and faster transistors are currently powering revolutions in information technology and artificial intelligence. Furthermore, large-area thin-films of semiconductors offer a realistic solution to decarbonising the world's energy production through efficient solar to electrical energy conversion. With transistor feature sizes reaching the nanometre length scale and multijunction thin film photovoltaics offering very efficient energy production, surfaces increasingly influence the function of these devices. Currently there are few methods available to observe the electrical properties of semiconductor surfaces and interfaces on nanometre length scales, with high enough time resolution. This Fellowship will lead the creation of a unique instrument for understanding the electrical properties of semiconductor surfaces and interfaces. The techniques of scanning tunnelling microscopy, scanning near-field optical microscopy and optical pump terahertz probe spectroscopy will be combined in a single instrument able to probe electrical properties of materials at unprecedented spatial and temporal resolution. During the fellowship the novel instrument will be exploited to improve the power conversion efficiency and stability of solar cells by revealing the mechanisms of charge recombination, trapping and degradation at surfaces and grain boundaries. While the fellowship is focussed on study of semiconductors for energy conversion, active engagement with the wider scientific community, government and industry over the 5 years will lead to dissemination of the technique and instrumentation into other areas of surface science and beyond.