Origin of the 2D electron gas at the SrTiO₃ surface

April 16, 2022

In a study published in Advanced Materials, researchers report that the surface of SrTiO₃ (the most common material used in the field of oxide electronics) exhibits a 2D electron gas due to the presence of a TiO₂ double layer.

Measured atomic and electronic structures from the as-prepared surface (A) and the surface after the deposition of 1 ML SrO (B).

Scientific Achievement

Using an array of in situ X-ray techniques at Advanced Photon Source, we discovered that the surface of SrTiO₃, the most common material used in the field of oxide electronics, exhibits a 2D electron gas (2DEG) due to the presence of a defect known as the TiO₂ double layer.

Significance and Impact

A wide array of theories have been proposed for the unexpected appearance of conductivity at the surfaces / interfaces of well-known insulators. Our results show that defects present at interfaces of even the most carefully prepared samples can lead to a 2DEG. This work was selected for Advanced Photon Source Highlight.

Research Details

In situ synchrotron X-ray studies during growth by oxide molecular beam epitaxy (APS, Sector 33)
After growth of each monolayer, in-vacuum transfer to a neighbor beamline (APS, Sector 29) for angle-resolved photoemission spectroscopy

DOI: 10.1002/adma.202200866

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