Pd nanoparticle (NP) coated LaAlO3/SrTiO3 (LAO/STO) heterointerface exhibits more notable conductance (G) change while varying the ambient gas (N2, H2/N2, and O2) and illuminating with UV light (wavelength: 365 nm) than a sample without the NPs. Simultaneous Kelvin probe force microscopy and transport measurements reveal close relationships between the surface work function (W) and G of the samples. Quantitative analyses suggest that a surface adsorption/desorption-mediated reaction and redox, resulting in a band-alignment modification and charge-transfer, could explain the gas- and photo-induced conductance modulation at the LAO/STO interface. Such surface-and-interface coupling enhanced by catalytic Pd NPs is a unique feature, quite distinct from conventional semiconductor hetero-junctions, which enables the significant conductance tunability at ultrathin oxide heterointerfaces by external stimuli.
Bibliographical noteFunding Information:
The authors thank J. G. Connell and S. S. A. Seo for valuable discussions. This work was supported by Basic Science Research Program and the Quantum Metamaterials Research Center through the National Research Foundation of Korea Grant (NRF-2013R1A1A2063744, NRF-2008-0061893) and New & Renewable Energy Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) Grant (20123010010160). NYC and JYD acknowledge the financial support of Hong Kong Ph.D fellowship scheme and financial support from NSFC/RGC Joint Research Grant (G-YJ69 and N_PolyU517/14).
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