Electric-field-driven dual-functional molecular switches in tunnel junctions

To avoid crosstalk and suppress leakage currents in resistive random access memories (RRAMs), a resistive switch and a
current rectifier (diode) are usually combined in series in a one diode–one resistor (1D–1R) RRAM.

However, this complicates the design of next-generation RRAM, increases the footprint of devices and increases the operating voltage as the potential drops over two consecutive junctions1. Here, we report a molecular tunnel junction based on molecules that provide an unprecedented dual functionality of diode and variable resistor, resulting in a molecular-scale 1D–1R RRAM with a current rectification ratio of 2.5 × 10⁴ and resistive on/off ratio of 6.7 × 10³, and a low drive voltage of 0.89 V. The switching relies on dimerization of redox units, resulting in hybridization of molecular orbitals accompanied by directional ion migration. This electric-field-driven molecular switch operating in the tunnelling regime enables a class of molecular devices
where multiple electronic functions are preprogrammed inside a single molecular layer with a thickness of only 2 nm.

References:

Yingmei Han, Cameron Nickle, Ziyu Zhang, Hippolyte P. A. G. Astier, Thorin J. Duffin, Dongchen Qi, Zhe Wang, Enrique del Barco, Damien Thompson and Christian A. Nijhuis
“Electric-field-driven dual-functional molecular switches in tunnel junctions”
Nature Materials 19, 843–848 (2020)

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