Solid phase epitaxial growth of high mobility La:BaSnO3 thin films co-doped with interstitial hydrogen

Niedermeier, Christian A. and Rhode, Sneha and Fearn, Sarah and Ide, Keisuke and Moram, Michelle A. and Hiramatsu, Hidenori and Hosono, Hideo and Kamiya, Toshio

Abstract.

This work presents the solid phase epitaxial growth of high mobility La:BaSnO3t hin films on SrTiO3 single crystal substrates by crystallization through thermal annealing of nanocrystalline thin films prepared by pulsed laser deposition at room temperature. The La:BaSnO3thin films show high epitaxial quality and Hall mobilities up to 26 ± 1 cm2/Vs. Secondary ion mass spectroscopy is used to determine the La concentration profile in the La:BaSnO3 thin films, and a 9%–16% La doping activation efficiency is obtained. An investigation of H doping to BaSnO3 thin films is presented employing H plasma treatment at room temperature. Carrier concentrations in previously insulating BaSnO3thin films were increased to 3 × 1019 cm−3 and in La:BaSnO3thin films from 6 × 1019 cm−3 to 1.5 × 1020 cm−3, supporting a theoretical prediction that interstitial H serves as an excellent n-type dopant. An analysis of the free electron absorption by infrared spectroscopy yields a small (H,La):BaSnO3 electron effective mass of 0.27 ± 0.05 m0 and an optical mobility of 26 ± 7 cm2/Vs. As compared to La:BaSnO3 single crystals, the smaller electron mobility in epitaxial thin films grown on SrTiO3 substrates is ascribed to threading dislocations as observed in high resolution transmission electron micrographs.

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Department of Materials
Imperial College London
Royal School of Mines
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London, SW7 2AZ - UK