Quantitative Determination of Native Point‐Defect Concentrations at the ppm Level in Un‐Doped BaSnO3 Thin Films

Advanced Functional Materials, vol. 32

Abstract

Abstract The high‐mobility, wide‐bandgap perovskite oxide BaSnO3 is taken as a model system to demonstrate that the native point defects present in un‐doped, epitaxial thin films grown by hybrid molecular beam epitaxy can be identified and their concentrations at the ppm level determined quantitatively. An elevated‐temperature, multi‐faceted approach is shown to be necessary: oxygen tracer diffusion experiments with secondary ion mass spectrometry analysis; molecular dynamics simulations of oxygen‐vacancy diffusion; electronic conductivity studies as a function of oxygen activity and temperature; and Hall‐effect measurements. The results indicate that the oxygen‐vacancy concentration cannot be lowered below 1017.3 cm−3 because of a background level of barium vacancies (of this concentration), introduced during film growth. The multi‐faceted approach also yields the electron mobility over a wide temperature range, coefficients of oxygen surface exchange and oxygen‐vacancy diffusion, and the reduction enthalpy. The consequences of the results for the lowest electron concentration achievable in BaSnO3 samples, for the ease of oxide reduction and for the stability of reduced films with respect to oxidation, are discussed.

Authors 10

1. Kendra Solveig Belthle Aachen Institute of Physical Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Physical Chemistry RWTH Aachen University 52056 Aachen Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

2. Ute N. Gries Aachen Institute of Physical Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Physical Chemistry RWTH Aachen University 52056 Aachen Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

3. Michael P. Mueller Aachen Institute of Physical Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Physical Chemistry RWTH Aachen University 52056 Aachen Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

4. Dennis Kemp Aachen Institute of Physical Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Physical Chemistry RWTH Aachen University 52056 Aachen Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

5. Abhinav Prakash

   University of Minnesota · University of Minnesota System

   Affiliation as printed

   Department of Chemical Engineering and Materials Science University of Minnesota Minnesota MN 55455 USA

   Department of Chemical Engineering and Materials Science, University of Minnesota, Minnesota, MN, 55455 USA

6. Marc‐André Rose

   Forschungszentrum Jülich

   Affiliation as printed

   Peter Gruenberg Institute (PGI 7) Forschungszentrum Juelich GmbH 52428 Juelich Germany

   Peter Gruenberg Institute (PGI 7), Forschungszentrum Juelich GmbH, 52428 Juelich, Germany

7. Jacqueline M. Börgers

   Forschungszentrum Jülich

   Affiliation as printed

   Peter Gruenberg Institute (PGI 7) Forschungszentrum Juelich GmbH 52428 Juelich Germany

   Peter Gruenberg Institute (PGI 7), Forschungszentrum Juelich GmbH, 52428 Juelich, Germany

8. Bharat Jalan

   University of Minnesota · University of Minnesota System

   Affiliation as printed

   Department of Chemical Engineering and Materials Science University of Minnesota Minnesota MN 55455 USA

   Department of Chemical Engineering and Materials Science, University of Minnesota, Minnesota, MN, 55455 USA

9. Felix Gunkel

   Forschungszentrum Jülich

   Affiliation as printed

   Peter Gruenberg Institute (PGI 7) Forschungszentrum Juelich GmbH 52428 Juelich Germany

   Peter Gruenberg Institute (PGI 7), Forschungszentrum Juelich GmbH, 52428 Juelich, Germany

10. Roger A. De Souza corresponding Aachen Institute of Physical Chemistry

    RWTH Aachen University

    Affiliation as printed

    Institute of Physical Chemistry RWTH Aachen University 52056 Aachen Germany

    Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany