High electrical conductivity in oxygen deficient BaSnO3 films

BaSnO3(BSO) films were grown epitaxially on MgO substrate under a wide range of pressures (from 20 to 0.03 Pa) by pulsed laser deposition. The structural, electrical, and optical properties of films were investigated. X-ray diffraction characterization reveals that the film unit cell volume increases gradually with decreasing the growth oxygen pressure while preserving the perovskite structure. The transport property measurement suggests that the film resistivity was tuned with variation from nearly insulator to metallic conductor by controlling the grown oxygen pressure, which was attributed to the presence of more oxygen vacancies in films during deposition. Remarkably, the lowest room-temperature resistivity of 8.07 x 10(-4) Omega cm was obtained in film grown in 0.3 Pa without any dopant, with the carrier concentration and mobility of 7.60 x 10(20) cm(-3) and 10.81 cm(2)/V respectively. All the BSO films have high transmittance of more than 80% in the visible range regardless of the oxygen pressure, whereas the optical band gaps increase from 3.49 to 3.70 eV, which was explained by the Burstein-Moss effect. (C) 2015 Elsevier B.V. All rights reserved.