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 m Omega.cm, with a mobility of 1.62 cm(2)V(-1)s(-1). To further reduce the resistivity, the films were vacuum-annealed at various temperatures in the range from 600 degrees C to 900 degrees C and the film annealed at 600 degrees C exhibited the lowest room temperature resistivity of 5 m Omega.cm with the highest mobility of 3.09 cm(2)V(-1)s(-1). The decrease of resistivity in the film vacuum-annealed at 600 degrees C 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.