Figure 3
Electrode-dependent capacitances and corresponding oxygen affinities of TaNx layers. (a) Variation in capacitance (ΔC/C0) acquired at 100 kHz as a function of dc voltage. (b) Quadratic voltage coefficient of capacitance as a function of the bottom electrode type; results were subsequently fitted using the equation provided in the main text. The observed variation in α reflects the formation of electrode-dependent thin interfacial layers and the corresponding oxygen affinity of each TaNx bottom electrode. A low oxygen affinity is indicative of a low redox reaction with an oxide active layer used in a memory cell. Note that Pt and Ta electrodes clearly and expectedly demonstrate low and high values of α, a finding that can be ascribed to their low and high oxygen affinities, respectively.
