Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 69: Focussed Session: Oxide Semiconductors for Device and Energy Applications 1

HL 69.3: Topical Talk

Donnerstag, 10. März 2016, 10:45–11:15, H11

Exploring and tailoring conductance phenomena in oxide films: An STM study — •Niklas Nilius — Carl von Ossietzky Universität Oldenburg

Electronic properties of classical semiconductors, e.g. Si, are adjustable with high accuracy and form the basis of todays information technology. Also oxides exhibit fascinating electronic features, e.g. a large spread in gap sizes, a correlated electronic behavior, metal-insulator transitions, anomalous temperature and voltage dependencies and superconductivity. Despite this potential, no satisfactory mechanistic understanding of oxide properties has been achieved so far and preparation of phase-clean materials remains challenging.

My talk demonstrates how thin-film oxides of high structural quality can be prepared and explored at atomic length-scales by STM. The approach yields direct correlation between structural parameters and electronic properties of the materials. Moreover, their conductance behavior becomes tunable, e.g. by stoichiometry and defect engineering, doping and interface control. I will present examples for low-gap oxides, e.g. Cu₂O and V₂O₃, and discuss how their electronic response is affected by intrinsic defects and dopants. For wide-gap materials, such as MgO and CeO₂, the interplay between conductance and low-dimensional edge and surface states as well as uncompensated polarity is addressed. Finally, the transition from binary to ternary oxides is introduced as a route to tune electronic properties. My talk aims at providing mechanistic insights into the structure-conductivity relationship rather than presenting materials of direct technological relevance.