LaInO3/BaSnO3 polar interface on MgO substrates

We report on a new property of the LaInO3 (LIO)/(Ba,La)SnO3 (BLSO) polar interface using MgO substrates. The growth of well-formed LIO/BLSO interface structures on non-perovskite MgO substrates was confirmed by reciprocal space mapping image and transmission electron microscopy. Subsequently, we measured electrical properties as a function of the La doping rate of the BLSO layer and found that the LIO/BLSO polar interface shows conductance enhancement after the deposition of the polar LaInO3 layer on the BLSO layer, in agreement with our earlier results on SrTiO3 (STO) substrates. However, different electrical properties of the interfaces were found on MgO from those on STO substrates; we observed conductance enhancement even at the interface with undoped BaSnO3 (BSO) on the MgO substrates. We attribute such different behavior to the difference in the Fermi levels of BSO on MgO and STO substrates, either due to the larger donor density or the smaller acceptor density in BSO on MgO. Using such a nominally undoped interface, we fabricated the field effect transistors and presented their performances with Ion/Ioff ∼ 109.