演題：Perovskite oxide heterostructures based on BaSnO3
講師：Kookrin Char 氏
（Seoul National University・Professor）
A wide-bandgap perovskite oxide semiconductor BaSnO3 was recently found to possess high mobility and excellent stability. Its single crystal mobility value of about 300 cm2 V-1 s-1 in the doping range of 1019~1020 cm-3, when n-type La dopants in place of Ba are used, is the highest among all the semiconductors. Furthermore, the oxygen diffusion constant in BaSnO3 was measured to be several orders of magnitude lower than 3d transition metal perovskite oxides, demonstrating super stability of the material. Taking advantage of such properties, excellent field effect transistors were recently demonstrated using amorphous gate oxides (AlOx and HfOx) as well as high-k epitaxial gate oxides such as LaInO3 and BaHfO3, which led to the development of an all-perovskite transparent high mobility field effect transistor. In addition, p-type doping by K in place of Ba is feasible and the pn-junctions made with K-doped BaSnO3 and La-doped BaSnO3 were demonstrated to exhibit near-ideal IV characteristics. Moreover, 2DEG behavior is found at the polar interface of BaSnO3 and LaInO3. We will go over the parameters that control the 2DEG behavior and discuss the mechanism behind such behavior.In spite of these tremendous progresses, the device performances are currently limited by defects such as threading dislocations. Once all the major defects are removed, the perovskite oxide semiconductor BaSnO3 system, especially when it is combined with other perovskite oxides, is expected to offer much more opportunities for science and technology.