Surface and interface electronic properties of emerging oxide semiconductors: a feasibility study of CdO

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Improvements in the crystalline quality of both nitride- and oxide-based semiconductors in recent years has resulted in increasing interest in these materials for future device applications. For the majority of micro- and opto-electronic devices, the interfaces between the semiconductors and the metal contacts largely dictates their properties. Consequently, to fully realise the potential of many of these nitride- and oxide-based semiconductors it is necessary to understand the fundamental properties of their near-surface and -interface regions. We have contributed internationally with our understanding of the near-surface space-charge properties of conventional III-V semiconductors and nitride-based materials - including dilute III-V nitrides e.g. GaNAs and InNSb [EPSRC grants GR/R93872/01 and GR/S56030/01] and III-nitrides e.g. InN and InGaN [EPSRC grant EP/C535553/1] - with the surface sensitive techniques of high resolution electron energy-loss spectroscopy (HREELS) and x-ray photoemission spectroscopy (XPS). This proposal seeks to extend the experimental and theoretical methodology we have developed to invesitgate for the first time the near-surface and -interface properties of metalorganic vapour-phase epitaxy grown high-quality single-crystalline CdO, the II-VI analogue of InN. We will employ a combination of HREELS and XPS to investigate the space-charge profiles of both clean CdO surfaces and interfaces formed when elements of different electronegativities are deposited. Furthermore, this study will determine the feasibility of moving from the more established nitrides towards the less developed oxides.