Resistive Electrical Switching of Nonvolatile Memories from Electrodeposited Copper Tetracyanoquinodimethane (CuTCNQ)
CuTCNQ is a charge transfer complex displaying resistive electrical switching when sandwiched between Cu and Al contacts. Corresponding memory cells switch from a native high resistive OFF state (HRS) to a low resistive ON state (LRS) by applying a negative voltage to the Al with respect to the Cu. Inversion of the signal polarity leads to switching from the LRS to the HRS. Typical CuTCNQ preparation occurs by a chemical reaction of a Cu substrate with TCNQ, involving (partial) corrosion of the metal. In this contribution we present electrodeposition of CuTCNQ on Au and Pt substrates, leading – in contrast to previously published dendritically crystal growth – to relatively smooth, micrometer thick layers. Corresponding large area cross-bar memory arrays (200m by 200m, with Al top contacts) exhibited up to several thousand write/erase cycles with an ON/OFF current ratio of 5-10. Furthermore preliminary growth experiments with blanket tungsten bottom contact Metal–Oxide–Semiconductor (CMOS) wafers with 250 nm diameter contact holes showed that electrodeposition is a suitable method for CuTCNQ integration.
Pietro VINCENZINI and Giuseppe D'ARRIGO
R. Müller et al., "Resistive Electrical Switching of Nonvolatile Memories from Electrodeposited Copper Tetracyanoquinodimethane (CuTCNQ)", Advances in Science and Technology, Vol. 54, pp. 464-469, 2008