Reversible and Persistent Photoconductivity at the NdGaO3/SrTiO3 Conducting Interface

Source: arXiv

ABSTRACT The interface between the band gap insulators LaAlO3 and SrTiO3 is known to
host a highly mobile two-dimensional electron gas. Here we report on the
fabrication and characterization of the NdGaO3/SrTiO3 interface, that shares
with LaAlO3/SrTiO3 an all-perovskite structure, the insulating nature of the
single building block and the polar-non polar character. Our work demonstrates
that in NdGaO3/SrTiO3 a metallic layer of mobile electrons is formed, with
properties comparable to LaAlO3/SrTiO3. The localization of the injected
electrons at the Ti sites, within a few unit cells from the interface, was
proved by Atomic-scale-resolved EELS analyses. The electric transport and
photoconduction of samples were also investigated. We found that irradiation by
photons below the SrTiO3 gap does not increase the carrier density, but
slightly enhances low temperature mobility. A giant persistent
photoconductivity effect was instead observed, even under irradiation by low
energy photons, in highly resistive samples fabricated at non-optimal
conditions. We discuss the results in the light of different mechanisms
proposed for the two-dimensional electron gas formation. Both the ordinary and
the persistent photoconductivity in these systems are addressed and analyzed.

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Available from: Claudia Cantoni, Sep 25, 2015
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