Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 58: Focus Session: Copper oxide semiconductors – An attractive material for photovoltaics?

HL 58.2: Topical Talk

Mittwoch, 13. März 2013, 15:30–16:00, H13

Intrinsic and hydrogen related impurities in Cu₂O — •Graeme Watson — School of Chemistry and CRANN, Trinity College Dublin, Dublin 2, Ireland

Cuprous oxide (Cu₂O) is a prototypical p-type conducting oxide with applications in dilute magnetic semiconductors, low cost solar cells, gas sensors and catalysis. It is also the parent compound of many p-type transparent conducting oxides (TCOs), which are thought to retain the valence band features and conduction mechanisms of Cu₂O. Understanding conduction in Cu₂O is therefore vital to the optimization of Cu-based materials for many applications. Calculation of the native defects in Cu₂O show that GGA and GGA+U are not capable of obtaining an accurate description of the polaronic nature of p-type defects in Cu₂O,[1] however, hybrid-DFT yields deep single-particle levels, consistent with experimentally observed activated, polaronic conduction. Our calculated transition levels for simple and split copper vacancies explain for the first time the source of the two distinct hole states seen in DLTS experiments [2] and demonstrate that Cu₂O can never be made n-type by native defects.[3] We also investigate the behaviour of hydrogen in Cu₂O,[4] and elucidate the “quasi-atomic” hydrogen site that Muon spectroscopy has been unable to identify. We discuss the impact of H on the electrical properties of Cu₂O-based materials, and propose methods to increase device performance.

[1] J. Chem. Phys., 131, 124703 (2009), [2] Phys. Rev. Lett., 103, 096405 (2009), [3] J. Phys. Chem. Lett. 1, 2582 (2010), [4] Phys. Rev. Lett., 106, 186403 (2011)