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Type of Document Dissertation Author Amsinck, Christian Johannes, URN etd-03232006-164254 Title Molecular Electronic Memories Degree PhD Graduate Program Electrical Engineering Advisory Committee
Advisor Name Title Paul Franzon Committee Chair Gregory Parsons Committee Member John Muth Committee Member Veena Misra Committee Member Keywords
- molecular memory
- stiction
- scaling
- molecular electronics
- nanotechnology
- nanoelectronics
Date of Defense 2006-03-23 Availability unrestricted Abstract The feasibility of building large memories using molecular electronic devices with bistableconductance-state memory has been investigated. A novel fabrication method for twoterminal
molecular memory devices that is integrateable into large-scale arrays while
avoiding top-contact evaporation on a molecular monolayer has been developed. A
sacrificial layer underneath the top contact metal is wet-etched to create free-standing
cantilevers in aqueous solution and a self-assembled monolayer is formed on the underside
of the cantilever. Subsequent atmospheric drying causes the freestanding structure to
become permanently adhered to the substrate, resulting in a two-terminal molecular
structure. This device has been investigated with alkanethiol monolayers as a proof-ofconcept,
and the expected decrease in current with increasing chain length is observed. The
measured current density in control devices without molecules is also consistent with
models of loaded cantilevers. Previously characterized molecules exhibiting memory
behavior were also investigated and demonstrated bistable memory effects similar to earlier
observations.
The scalability of such bistable molecular memory devices was analyzed from a circuits
perspective, and the impact of different system parameters was quantified. It is necessary to
build large arrays with at least several hundred molecular memory cells along each
dimension, in order to prevent peripheral circuitry from dominating the area. It is
quantitatively shown how this requirement constrains the minimum allowable
forward/reverse-bias rectification ratio of the molecular devices, as well as the minimal
on/off ratio of the two molecular conductance states. The parasitic wiring impedance is
negligible in the case of metallic interconnect, but the impedance of currently available
molecular wires makes large-scale all-molecular arrays infeasible.
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