Largely\nEnhanced Mobility in Trilayered\nLaAlO₃/SrTiO₃/LaAlO₃ Heterostructures

Abstract

LaAlO₃ (LAO)/SrTiO₃ (STO)/LaAlO₃ (LAO) heterostructures were epitaxially deposited on TiO₂-terminated (100) SrTiO₃ single-crystal substrates\nby laser molecular beam epitaxy. The electron Hall mobility of 1.2\n× 10⁴ cm²/V s at 2 K was obtained in our\ntrilayered heterostructures grown under 1 × 10^–5 Torr, which was significantly higher than that in single-layer 5\nunit cells LAO (∼4 × 10³ cm²/V s)\nepitaxially grown on (100) STO substrates under the same conditions.\nIt is believed that the enhancement of dielectric permittivity in\nthe polar insulating trilayer can screen the electric field, thus\nreducing the carrier effective mass of the two-dimensional electron\ngas formed at the TiO₂ interfacial layer in the substrate,\nresulting in a largely enhanced mobility, as suggested by the first-principle\ncalculation. Our results will pave the way for designing high-mobility\noxide nanoelectronic devices based on LAO/STO heterostructures.