Electrical and optical properties of Sb-doped BaSnO₃ epitaxial films grown by pulsed laser deposition

In this paper we report the structural, electrical and optical properties of epitaxial Ba(Sb_xSn_1−x)O₃ (x = 0–0.30) (BSSO) films grown on SrTiO₃(0 0 1) substrates by the pulsed laser deposition method. The investigation reveals that the transport and optical characteristics of BSSO films depend very sensitively on the Sb-doping content. Temperature-dependent resistivity measurements show that at low Sb contents (x = 0.03, 0.07) the metal–semiconductor transition occurs at 150 K and 80 K, respectively, and the semiconductor behaviour appears in high doped (x = 0.15, 0.30) films. The transmittance decreases significantly from about 80% to nearly zero in the visible region and the optical band gap shifts from 3.48 to 4.0 eV with increasing Sb content in the films. The lowest room-temperature resistivity of 2.43 mΩ cm with carrier density and mobility of 1.65 × 10²¹ cm⁻³ and 1.75 cm² V⁻¹ s⁻¹ was obtained in the films with doping at x = 0.07. By employing them as bottom electrodes we have fabricated transparent Pb(Zr_0.52Ti_0.48)O₃ ferroelectric capacitors showing square polarization–electric field hysteresis loops, indicating that these perovskite-type BSSO films at low doping can be potentially used in transparent devices especially based on all-perovskite heterostructures.