Figure 4: Cross-sectional electron microscopy of Pt/a-GaOx(90 nm)/ITO devices after switching to HRS and LRS.
From: Bulk mixed ion electron conduction in amorphous gallium oxide causes memristive behaviour
(a) STEM images and the corresponding EDX elemental mapping of O (yellow) and Ga (red) of the HRS film after polarization at +4 V during the 3rd −4 V→+4 V voltage-sweep cycle at vsw of 0.5 V s−1. (b) STEM images of the −4 V-biased film in LRS. The scale bars in (a and b) are 40 nm. The solid white lines in the O EDX mapping images are a guide to the eye for the boundaries of the GaOx film. (c) EDX line profiles of O and Ga scanned from the Pt to the ITO side along the white dashed lines in the STEM images in a and b. The line profiles of O are obtained by subtracting the background noise determined from an Al standard sample. The EDX line profiles apparently show the enrichment of O near the TE/film boundary (magenta-filled peak area) by anodic polarization and the decrease of O at the BE/film boundary (cyan-filled peak area) by cathodic polarization. In contrast, the Ga line profile remains flat, independent of anodic or cathodic polarization.
