Accelerated optimization of transparent, amorphous zinc-tin-oxide thin films for optoelectronic applications
Matthew J. Wahila,
Zachary W. Lebens-Higgins,
Keith T. Butler,
Daniel Fritsch,
Robert E. Treharne,
Robert G. Palgrave,
Joseph C. Woicik,
Benjamin J. Morgan,
Aron Walsh,
Louis F. J. Piper
Affiliations
Matthew J. Wahila
Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902, USA
Zachary W. Lebens-Higgins
Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902, USA
Keith T. Butler
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
Daniel Fritsch
Department Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
Robert E. Treharne
Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZF, United Kingdom
Robert G. Palgrave
University College London, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, United Kingdom
Joseph C. Woicik
Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
Benjamin J. Morgan
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
Aron Walsh
Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
Louis F. J. Piper
Materials Science and Engineering, Binghamton University, Binghamton, New York 13902, USA
In the last decade, transparent amorphous oxide semiconductors (TAOS) have become an essential component of many electronics, from ultra high resolution displays to solar cells. However, these disordered oxides typically rely on expensive component metals like indium to provide sufficient charge carrier conduction, and their optoelectronic properties are not as predictable and well-described as those of traditional, crystalline semiconductors. Herein we report on our comprehensive study of the amorphous zinc-tin-oxide (a-ZTO) system for use as an indium-free, n-type TAOS. Using a combination of high-throughput co-deposition growth, high resolution spectral mapping, and atomistic calculations, we explain the development of disorder-related subgap states in SnO2-like a-ZTO and optical bandgap reduction in ZnO-like a-ZTO. In addition, we report on a composition-induced electronic and structural transition in ZnO-like a-ZTO resulting in an exceptionally high figure of merit, comparable to that of amorphous indium-gallium-zinc-oxide. Our results accelerate the development of a-ZTO and similar systems as indium-free TAOS materials.
