July 18, 2006Small
Reversible and Controllable Switching of a Single‐Molecule Junction
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Implication
Experimental study demonstrates reversible conductance switching in single bipyridyl-dinitro molecules, highlighting the feasibility of single-molecule memory elements.
Key Points
- To determine whether voltage-induced conductance switching can occur reversibly within an individual molecule rather than arising from metallic filament formation or ensemble contact artifacts.
- Fabricated mechanically controllable break-junctions (MCBJ) using electron-beam lithography to achieve sub-picometer electrode spacing under ultrahigh vacuum and cryogenic conditions (100 K).
- Deposited dilute solutions of bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT) and reference bipyridyl oligophenylene-ethynylene dithiol (BP-DT) onto gold leads across seven junction samples per molecule.
- Acquired raw current-voltage sweeps, differential conductance curves, and write-read-erase pulse patterns across repeated junction opening and closing cycles.
- Single BPDN-DT molecules exhibited voltage-triggered switching with hysteresis at positive and negative thresholds (±0.7 V to ±1.4 V) across >500 cycles, while the control molecule (BP-DT) displayed only monotonic non-switching traces.
- Conducted write (+1.6 V) and erase (−1.6 V) pulses yielding off-state currents of 0.05–0.13 nA and on-state currents of 0.9–3.6 nA, achieving an on/off bit separation ratio between 7 and 70.
- Readout operations remained non-destructive with signal decreases of only 5% over continuous 30-second read times at 100 K, demonstrating stable nonvolatile memory retention.
Cite This Study
Lörtscher et al. (2006) studied this question.