High mobility La-doped BaSnO$_{\mathrm{3}}$ on non-perovskite MgO substrate

(Ba,La)SnO$_{\mathrm{3}}$ is a transparent perovskite oxide with high electron mobility and excellent oxygen stability. Field effect device with (Ba,La)SnO$_{\mathrm{3}}$ channel was reported to show good output characteristics on STO substrate. Here, we fabricated (Ba,La)SnO$_{\mathrm{3\thinspace }}$films and field effect devices with (Ba,La)SnO$_{\mathrm{3}}$ channel on non-perovskite MgO substrates, which are available in large size wafers. X-ray diffraction and transmission electron microscope (TEM) images of (Ba,La)SnO$_{\mathrm{3\thinspace }}$films on MgO substrates show that the films are epitaxial with many threading dislocations. (Ba,La)SnO$_{\mathrm{3}}$ exhibits the high mobility with 97.2 cm$^{\mathrm{2}}$/Vs at 2 {\%} La doping on top of 150 nm thick BaSnO$_{\mathrm{3}}$ buffer layer. Excellent carrier modulation was observed in field effect devices. FET performances on MgO substrates are slightly better than those on SrTiO$_{\mathrm{3}}$ substrates in spite of the higher dislocation density on MgO than on SrTiO$_{\mathrm{3}}$ substrates. These high mobility BaSnO$_{\mathrm{3}}$ thin films and transistors on MgO substrates will accelerate development for applications in high temperature and high power electronics.