Eur. Phys. J. B (2018) 91: 67
https://doi.org/10.1140/epjb/e2018-80489-x

Regular Article

Electrical and material properties of hydrothermally grown single crystal (111) UO₂

¹ Department of Engineering Physics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7765, USA
² University of Nebraska, Walter Scott Engineering Center, Lincoln, NE 68588-0656, USA
³ Department of Electrical and Computer Engineering, University of Nebraska, Walter Scott Engineering Center, Lincoln, NE 68588-0511, USA
⁴ Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7765, USA
⁵ Nebraska Center for Energy Sciences Research, University of Nebraska, 230 Whittier Research Center, 2200 Vine Street, Lincoln, NE 68583-0857, USA
⁶ CAS Key Lab of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
⁷ Department of Physics, University of Nebraska at Omaha, 60th and Dodge Streets, Omaha, NE 68182-0266, USA
⁸ Department of Physics and Astronomy, University of Nebraska-Lincoln, Theodore Jorgensen Hall, 855 North 16th Street, Lincoln, NE 68588-0299, USA

^a e-mail: Christina.Dugan@afit.edu

Received: 22 August 2017
Received in final form: 5 January 2018
Published online: 16 April 2018

Abstract

The semiconductor and optical properties of UO₂ are investigated. The very long drift carrier lifetimes, obtained from current–voltage I(V) and capacitance–voltage C(V) measurements, along with the well-defined optical properties provide little evidence of an abundance of material defects away from the surface region. Schottky barrier formation may be possible, but very much dependent on the choice of contact and surface stoichiometry and we find that Ohmic contacts are in fact favored. Depth resolved photoemission provided evidence of a chemical shift at the surface. Density functional theory, with the Heyd-Scuseria-Ernzerhof (HSE) functional, indicates a band gap of a 2.19 eV and an anti-ferromagnetic ground state. Ellipsometry measurements indicates at UO₂ is relatively isotropic with a band gap of approximately 2.0 eV band gap, consistent with theoretical expectations.