Transparent oxide semiconductors (Ba,La)SnO$_{3}$ with high mobility at room temperature

We present our discovery of (Ba,La)SnO$_{3}$ system exhibiting electrical mobility at 300 K of 200-320 cm$^{2}$V$^{-1}$s$^{-1}$ in a doping range from 1.0x10$^{19}$ to 4.0x10$^{20}$ cm$^{-3}$. Moreover, their conductivity values were as large as around 10$^{4}$ S/cm, being comparable to those of indium tin oxides. The system yet shows the optical gap around 3.33 eV and only slight increase of the in-gap states, maintaining visual transparency. Several unique physical properties of (Ba,La)SnO$_{3}$ are also discussed: a superior oxygen stability evidenced by persistent transport properties under high temperature environments, a small effective mass coming from the ideal Sn-O-Sn bonding in a cubic perovskite, small disorder effects due to doping away from the main conduction channels (SnO$_{6}$ octahedra network) and reduced carrier scattering due to the high dielectric constant. (Ba,La)SnO$_{3}$ thus holds great potential for realizing transparent, high power, high temperature functional devices.