Structural, electrical, and luminescence characteristics of vacuum-annealed epitaxial (Ba,La)SnO3 thin films

Abstract

The correlation between the structural, electrical, and luminescence behaviors of La-doped BaSnO3 (LBSO) epitaxial films was intensively studied. We found that Sn2+ defects and oxygen vacancies control the electrical properties of epitaxial LBSO films that are grown on (001)-oriented SrTiO3 substrates using pulsed laser deposition. Under optimized deposition condition, the films exhibit room temperature resistivity of 16 mΩ·cm, with a mobility of 1.62 cm2V−1s−1. To further reduce the resistivity, the films were vacuum-annealed at various temperatures in the range from 600℃ to 900℃ and the film annealed at 600℃ exhibited the lowest room temperature resistivity of 5 mΩ·cm with the highest mobility of 3.09 cm2V−1s−1. The decrease of resistivity in the film vacuum-annealed at 600℃ originates from the higher concentration of Sn2+ ions and oxygen vacancies, which was also confirmed from photoluminescence studies, in which emission peaks associated with Sn2+ defects were observed at 710 and 910 nm. Raman analysis revealed the presence of defect states related to octahedral tilting in vacuum-annealed LBSO films. Our studies show that the electrical properties of epitaxial films could be controlled by the Sn2+ defects generated with oxygen vacancies during the vacuum-annealing of the films. Open image in new window