Ta doped SrSnO3 epitaxial films as transparent conductive oxide

We report the optical and transport properties of transparent conducting Ta doped SrSnO3 (SSTO) epitaxial films grown on MgO substrate by pulsed laser deposition. The effects of Ta ions doping on the microstructure and physical properties of SSTO films were investigated. Atomic force microscopy images confirm the smooth surface and low roughness of all films. X-ray photoelectron spectrum measurement shows that Ta ions are presented in the +5 state. All films have the optical transmittance of more than 90% in a wide wavelength range from 400 nm to at least 2000 nm. The band gaps of SSTO films calculated from the optical transmittances increase gradually from 4.45 to 4.63 eV with increasing Ta content. The SSTO films at x = 0.05 exhibit the lowest room-temperature resistivity of 3.33 mΩcm, and correspondingly the mobility reaches value as high as 18.5 cm2/Vs at a carrier concentration of about 1.01 × 1020 cm−3. This mobility value is much larger than that of our previously prepared Sb doped SrSnO3 films. The metal-insulator transition of resistivity was analyzed using the Coulomb interactions and electron-electron scattering effects. Such a transparent conductive oxide with the perovskite structure has a promising potential application in optoelectronic devices.