Abstract
The dynamics of electrostatic potential barriers at grain boundaries (GBs) in Nb-doped SrTiO3 bicrystals is investigated using a unique combination of bulk and in-situ TEM electrical measurements across isolated GBs, coupled with electron holography under in-situ applied bias. The Nb bulk-doped bicrystals exhibit a positive GB potential that suppresses reversibly under applied bias greater than the nonlinearity threshold in the current-voltage curve. This suppression is interpreted as break-down of the potential barrier to current transport. The results on Nb bulk-doped bicrystals have been compared to those in which Mn has been added as a grain boundary specific dopant. This acceptor doping of the grain boundary causes an appreciable increase in the grain boundary resistance and extension of the nonlinear regime. A preliminary account of static electron holography shows a relatively flat potential profile across the GB, indicating probable compensation of donor states at the GB core with Mn-acceptors. Interestingly, the phase profile under applied bias in this case exhibits a reversible 'dip' at the GB which is interpreted as an activation of GB trap states due to Mn-acceptor dopants trapping extra electrons (the majority charge carriers) at the GB core, inducing a negative GB potential, and diminishing current transport until the threshold bias is exceeded. The synergistic combination of nanoscale TEM measurements coupled with traditional macroscopic electrical measurements is emphasized.
Original language | English (US) |
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Pages (from-to) | 189-198 |
Number of pages | 10 |
Journal | Interface Science |
Volume | 8 |
Issue number | 2 |
State | Published - Aug 1 2000 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Condensed Matter Physics