Electrochemical memristive devices based on submonolayer metal deposition

This paper explores the concept of an analog memristive device based on reversible electrochemical deposition and deplating of a submonolayer metal layer on a 108 Ω resistive bar. Initial feasibility experiments demonstrate a continuous resistance change by seven orders of magnitude during physical vapor deposition of Cu on TaNx/SOI, with the most promising range from 5.6 × 107 to 1.1 × 107 Ω/□ during a 0.64 monolayer Cu deposition. Cyclic electrochemical deposition and deplating of Cu on a metal seed on SiO2 in a 0.01M CuSO4/H2SO4 pH 1.4 solution demonstrates a reversible resistance variation with a minimum of 10 ± 1 discrete resistance states. These initial results are promising but also reveal a key materials challenge: the need for controlled and reversible electrochemical deposition/deplating of a submonolayer metal on the surface of a relatively high resistivity (≥10−2 Ω m) material.