Infrared ellipsometry study of the confined electrons in a high-mobility gamma-Al2O3/SrTiO3 heterostructure
| Authors | |
|---|---|
| Year of publication | 2016 |
| Type | Article in Periodical |
| Magazine / Source | EPL |
| MU Faculty or unit | |
| Citation | |
| Doi | http://dx.doi.org/10.1209/0295-5075/113/47005 |
| Field | Solid matter physics and magnetism |
| Keywords | nfrared ellipsometry; Al2O3/SrTiO3 heterostructure |
| Description | With infrared ellipsometry we studied the response of the confined electrons in gamma-Al2O3/SrTiO3 (GAO/STO) 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 SrTiO3, we derive the sheet carrier density, N-s, the mobility, mu, and the depth profile of the carrier concentration. Notably, we find that N-s and the shape of the depth profile are similar as in LaAlO3/SrTiO3 (LAO/STO) heterostructures for which the itinerant carriers are believed to arise from a polar discontinuity. Despite an order of magnitude higher mobility in GAO/STO, as obtained from transport measurements, the derived mobility in the infrared range exhibits only a twofold increase. We interpret this finding in terms of the polaronic nature of the confined charge carriers in GAO/STO and LAO/STO which leads to a strong, frequency-dependent interaction with the STO phonons. Copyright (C) EPLA, 2016 |
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