Figure 2: Mechanistic determination through X-ray photoelectron spectroscopy (XPS).
From: Giant conductivity switching of LaAlO3/SrTiO3 heterointerfaces governed by surface protonation
(a) XPS of 4 uc LAO/STO showing the O1s region. The spectra are fit to the sum of three Gaussians assigned to free water (H2O), protonated oxygen (M–OH), and oxygen in the bulk perovskite lattice (M–O–M). (b) R measured following each treatment, with optical excitation denoted by solid purple lines and water treatment denoted by dashed blue lines. Here uncertainty is smaller than marker size. Evolution of areas of M–O–M (c), M–OH (d) and H2O (e) peaks normalized by the sum of M–O–M and M–OH measured while the sample was subjected to optical excitation and water immersion.
