Reversible Photomodulation of Two-Dimensional Electron Gas in LaAlO<sub>3</sub>/SrTiO<sub>3</sub> Heterostructures.
basic_science · Level V
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- Record sourced from PubMed, PMID 37418557.
- Also identified by DOI 10.1021/acs.nanolett.3c01076.
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Abstract
Long-lived photoinduced conductance changes in LaAlO<sub>3</sub>/SrTiO<sub>3</sub> (LAO/STO) heterostructures enable their use in optoelectronic memory applications. However, it remains challenging to quench the persistent photoconductivity (PPC) instantly and reproducibly, which limits the reversible optoelectronic switching. Herein, we demonstrate a reversible photomodulation of two-dimensional electron gas (2DEG) in LAO/STO heterostructures with high reproducibility. By irradiating UV pulses, the 2DEG at the LAO/STO interface is gradually transformed to the PPC state. Notably, the PPC can be completely removed by water treatment when two key requirements are met: (1) the moderate oxygen deficiency in STO and (2) the minimal band edge fluctuation at the interface. Through our X-ray photoelectron spectroscopy and electrical noise analysis, we reveal that the reproducible change in the conductivity of 2DEG is directly attributed to the surface-driven electron relaxation in the STO. Our results provide a stepping-stone toward developing optically tunable memristive devices based on oxide 2DEG systems.