Transport mechanisms in epitaxial SrTiO$_{3-\delta }$/Si (001) with varying oxygen deficiency

ORAL

Abstract

Epitaxial SrTiO$_{3}$ (STO) films were grown on p-Si (001) substrates using molecular beam epitaxy (MBE). Oxygen vacancies were introduced by controlling the oxygen pressure during growth resulting in oxygen deficient SrTiO$_{3-\delta }$ with $\delta $ up to 0.004. The single phase STO/Si films were of high crystalline quality as verified by x-ray diffraction (XRD), transmission electron microscopy (TEM), and had a surface roughness less than 0.5 nm (RMS) as measured by atomic force microscopy (AFM). Transport measurements in a Van der Pauw configuration showed semiconducting behavior. The competing effects of disorder and increased carrier concentration (n-type measured by Hall) due to oxygen vacancies influence the conduction behavior. Low oxygen pressure during growth induces more oxygen vacancies and a larger number of carriers (n-type, measured by Hall) but also leads to more disordered films. Transport in these more disordered films is strongly localized and can be fit to a Variable Range Hopping (VRH) model. Transport in films with a smaller number of oxygen vacancies is thermally activated. We consider competing effects in STO/Si: lattice mismatch with Si, strain and defects due to oxygen vacancies, structural dislocations and the bulk STO antiferrodistortive phase transition at 105K.

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Authors

  • Ryan Cottier

    Texas State University, Postdoc

  • Darren Depoy

    University of Michigan, Univeristy of Michigan, Texas A\&M University, UC Riverside, University of Massachusetts, STScI, NOAO, University of Texas, Cyclotron Institute, Texas A\&M University, ENEA, Italy, INFN, Italy, University of Texas at Austin, TX, Cyclotron Institute, TAMU, TX, Cyclotron Institute TAMU, TX, Cyclotron Institute - Texas A\&M University, Texas A\&M Univ, Texas A\&M University, Baylor University, Department of Physics and Astronomy, Texas A\&M University, College Station, Texas, School of Materials Science and Engineering, Shanghai Jiaotong University, Shanghai, 200240, China, Department of Materials Science and Engineering, Texas A\&M University, College Station, Texas, Department of Mechanical Engineering, Texas A\&M University, College Station, Texas, Texas State University, University of Texas at Arlington, Lawrence Berkeley National Laboratory, DESY, Department of Physics and Astronomy, Texas A\&M University, Department of Physics, Syracuse University, Department of Physics and Astronomy, Vanderbilt University, Texas A\&M University, Princeton University and Baylor University, Texas A\&M Univ at Qatar, Kazan Federal University, Max Planck Institute for Nuclear Physics, Institue for Quantum Science and Engineering (IQSE) and Department of Physics \& Astronomy, Texas A\&M University, College Station, Texas 77843, USA, MIT, Sandia National Laboratories, Albuquerque, New Mexico, Postgrad, ORNL, Muons Inc., Texas Lutheran University, West Virginia University, Lawrence Livermore National Laboratory, University of Kentucky, US Naval Academy, University of Dallas, U.S. Naval Academy, Univ of Texas, Arlington, Department of Physics, Texas A\&M University, College Station, TX 77845, Science and Petroleum Departments, Texas A\&M University in Qatar, Doha, Qatar, Rice University, Houston, Texas, USA, Department of Physics, Texas State University, Florida A\&M University, Texas A\&M University in Qatar, Doha, Qatar, Physics and Astronomy Dept., TCU, Geology Dept., TCU, Colorado College, University of Texas at El Paso, University of Texas at Brownsville, Rochester Institute of Technology, Baylor University, Texas A\&M, Princeton University, Baylor University, Princeton University, Texas A\&M University, Materials Science and Engineering and Department of Physics and Astronomy, Texas A\&M University; WPI-AIMR, Tohoku University, Japan, WPI-AIMR, Tohoku University, Department of Chemistry, Texas A\&M University, Materials Science and Engineering and Department of Physics and Astronomy, Texas A\&M University, WPI-AIMR, Tohoku University, Japan, Department of Physics and Astronomy, Texas A\&M University, College Station, Texas 77843, USA, Department of Physics and Astronomy, Texas A\&M University and WPI-Advanced Institute for Materials Research, Tohoku University, Japan, University of Texas at Austin, Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, JILA, NIST, Department of Physics and Astronomy, Texas A\&M University and Institute for Quantum Studies and Engineering, College Station, TX 77843-4242, USA, Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov street, Nizhny Novgorod 603950, Russia, Department of Physics, University of Texas at Austin, Rice University, Texas A&M University

  • Nikoleta Theodoropoulou

    Texas State University, Research Advisor