Complex oxide thin films and heterointerfaces: from novel phenomena to oxide electronics
Complex oxide thin films and heterointerfaces exhibit an incredible variety of intriguing phenomena. A remarkable example is the realization of two-dimensional electron gases (2DEGs) in LaAlO 3 /SrTiO 3 (LAO/STO) heterointerface, which has stimulated extensive efforts toward the understanding of fundamental physics and developing all-oxide electronic devices.
However, the carrier density (electron mobility) of the STO-based 2DEG is much higher (lower) than that of conventional semiconductors. In this presentation, it will be demonstrated that the electron mobility can be dramatically enhanced by replacing LAO with other perovskite oxides, such as (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.35 and Sr(Al 0.5 Ta 0.5 )O 3 , which have better lattice-matching and symmetry-matching . Furthermore, the orbital occupancy and carrier distribution of the 2DEGs at the STO-based heterointerfaces can be modulated by electric field effect (back gate and ionic liquid gate), which results in the observation of 1/B-period quantum Shubnikov deHaas oscillations  and B-period quantum Aharonov-Bohm oscillations. In addition, the practical device applications of complex oxide thin films and heterostructures are demonstrated.
The water-dissolvable and recyclable electronic device based on an erasable and recreatable 2DEG at the amorphous Sr 3 Al 2 O 6 /STO (a-SAO/STO) heterointerface is created .
Freestanding VO 2 membranes with flexibility and metal-insulator transition (MIT) are synthesized by etching of sacrificial water-soluble SAO layers.
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Host: Prof. Tae Won Noh