(a) STXM transmission image of the RRAM junction region (marked by a blue dashed box) and I0 (marked by a red short-dashed box) at low magnification, taken at 292.0 eV. The bottom and top electrodes are labeled as BE and TE. (b) Optical microscopic image of region A. (c, d) STXM transmission images of region A at 292.0 eV (c) and 538.2 eV (d). The damaged area at the bottom right-hand side of the RRAM junction region [shown in (c) and (d)] was due to the shadow mask which was partially blocked by debris.