Relationship Between Electrode Material, Valence Band Offset, and Nonlinearity in the Resistive Switching Behavior of Au/HfO2/M (M = TiN, W, Pt, or AlCu) Metal–Insulator–Metal Devices: Correlation Between Experimental and DFT Calculations

Abstract

We report on capacitance and current voltage nonlinearities to understand the resistive switching (RS) behavior in metal–insulator–metal (MIM) capacitors and its dependence on electrode material. Hafnium oxide (HfO₂) thin films were deposited at 350°C on various electrode materials, including platinum (Pt), tungsten (W), aluminum copper (AlCu), and titanium nitride (TiN). The current–voltage (I–V) sweep measurements were analyzed using the trap-controlled space-charge-limited conduction mechanism. The results were correlated to the first-principles calculations of the HfO₂/M heterostructures using the projector-augmented wave coupled to the generalized gradient approximation. The band structure, density of states, and partial density of states were calculated and interpreted. The band offset for the metal–oxide interfaces was determined using the Van de Walle and Martin model. Accordingly, we demonstrated that the dissipation energy of the MIM structures decreased with increasing valence band offset between the metal electrode and oxide. The link between I–V nonlinearity and capacitance–voltage variation was established through the concept of average electrostatic potential. We demonstrated that the observed C–V nonlinearity decreased with increasing potential discontinuity. These findings have promising implications for the design and optimization of future resistive random-access memory devices.