Largely Enhanced Mobility in Trilayered LaAlO 3 /SrTiO 3 /LaAlO 3 Heterostructures


LaAlO3 (LAO)/SrTiO3 (STO)/LaAlO3 (LAO) heterostructures were epitaxially deposited on TiO2-terminated (100) SrTiO3 single crystal substrates by laser molecular beam epitaxy. The electron Hall mobility of 1.2x10^4 cm2/Vs at 2 K was obtained in our tri-layered heterostructures grown under 1x10^-5 Torr, which was significantly higher than that in single layer 5 uc LAO (̃ 4x10^3 cm2/Vs) epitaxially grown on (100) STO substrates under the same conditions. It is believed that the enhancement of dielectric permittivity in the polar insulating trilayer can screen the electric field thus reducing the carrier effective mass of the two dimensional electron gas formed at the TiO2 interfacial layer in the substrate, resulting in a largely enhanced mobility, as suggested by the first-principle calculation. Our results will pave the way for designing high mobility oxide nanoelectronic devices based on LAO/STO heterostructures.

ACS Applied Materials and Interfaces