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arXiv · 1512.06008

Infrared ellipsometry study of the confined electrons in a high-mobility $\gamma$-Al$_2$O$_3$/SrTiO$_3$ heterostructure

Meghdad Yazdi-Rizi·Premysl Marsik·Benjamin Mallett·Adam Dubroka·Dennis Valbjørn Christensen·Yunzhong Chen·Nini Pryds·Christian Bernhard
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Abstract

With infrared ellipsometry we studied the response of the confined electrons in a $\gamma$-Al$_2$O$_3$/SrTiO$_3$ heterostructures in which they originate predominantly from oxygen vacancies. From the analysis of a so-called Berreman mode, that develops near the highest longitudinal optical phonon mode of SrTiO$_3$, we derive the sheet carrier density, ${N_{s}}$, the mobility, $\mu$, and also the depth profile of the carrier concentration. Notably, we find that ${N_{s}}$ and the shape of the depth profile are similar as in LaAlO$_3$/SrTiO$_3$ heterostructures for which the itinerant carriers are believed to arise from a polar discontinuity. The main differences concern the higher mobility and a relatively stronger confinement of the electrons in $\gamma$-Al$_2$O$_3$/SrTiO$_3$

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Meghdad Yazdi-Rizi, Premysl Marsik, Benjamin Mallett, Adam Dubroka, Dennis Valbjørn Christensen, Yunzhong Chen, Nini Pryds, Christian Bernhard. 2015-12-18. Infrared ellipsometry study of the confined electrons in a high-mobility $\gamma$-Al$_2$O$_3$/SrTiO$_3$ heterostructure. https://doi.org/10.1209/0295-5075%2F113%2F47005

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