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Large Persistent Photoconductivity in Strontium Titanate at Room Temperature

Published online by Cambridge University Press:  28 May 2015

Violet M. Poole
Affiliation:
Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814, U.S.A.
J. Dashdorj
Affiliation:
Department of Physics, University of Alabama at Birmingham, 1300 University Blvd., CH 310, Birmingham, AL 35294-1170, U.S.A.
Mary Ellen Zvanut
Affiliation:
Department of Physics, University of Alabama at Birmingham, 1300 University Blvd., CH 310, Birmingham, AL 35294-1170, U.S.A.
Matthew D. McCluskey
Affiliation:
Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814, U.S.A.
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Abstract

Strontium titanate (SrTiO3) is a wide-band-gap semiconductor with a variety of novel properties. In this work, bulk single crystal SrTiO3 samples were heated to 1200°C, resulting in the creation of point defects. These thermally treated samples showed large persistent photoconductivity (PPC) at room temperature. Illumination with sub-gap light (>2.9 eV) caused an increase in free-electron concentration by over two orders of magnitude. After the light is turned off, the conductivity persists at room temperature, with essentially zero decay over several days. The results of electron paramagnetic resonance (EPR) measurements suggest that a point defect is responsible for PPC because the photo-induced response of one of the EPR signals is similar to that seen for the PPC. Due to a large barrier for recapture, the photo-excited electron remains in the conduction band, where it contributes to the conductivity.

Type
Articles
Copyright
Copyright © Materials Research Society 2015 

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References

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