, Volume 97, Issue 2, pp 449-454
Date: 02 May 2009

Self-neutralization via electroreduction in photoemission from SrTiO3 single crystals

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The effect of bulk mediated neutralization in photoemission from insulating monocrystalline SrTiO3 was studied. Long-term measurements of the photoemission line shift and emission current allowed us to relate the observed systematic reduction of the surface charging to increasing conductivity of the samples. The bulk resistance of the SrTiO3 samples was found to scale with their thickness. We present a model of the observed behaviour based on well-conducting filaments connecting the surface with the grounded sample holder, similar to the hypothesis explaining resistive switching in single crystals and thin films of SrTiO3. In our model the changes of the local oxygen stoichiometry are driven by surface potential and consequently electric field and chemical gradients, which cause electroreduction and electromigration along extended defects in the crystals.