Figure 4
XPS binding energy depth profiles and summarized nitrogen diffusivity for N 1 s peaks. (a) Sample A, (b) Sample B, and (c) Sample C, ranging from 4 nm to 20 nm into the Ta2O5−x layer. The N 1 s spectra were de-convoluted into two different peaks: Ta 4p and N 1 s. (d) Summary of the variation in nitrogen contents with depth in the Ta2O5−x oxide layer for N1s/Ta4p peak areas ratio (a–c); the inset shows a schematic of the XPS measurements. The TaNx electrode used in Sample C had a larger area ratio of N1s/Ta4p than that in Sample B. However, the diffusivity of nitrogen atoms was greater for Sample B than Sample C, establishing unstable resistive switching compared with Sample C.
