MIT Department of Electrical Engineering & Computer Science

Molecular Wires: Can Organic Molecules Be Used To Interconnect

Supriyo Datta
Purdue University; Visiting MIT, EECS & RLE

Monday, March 9, 1998
4:00 PM (refreshments 3:45)
Edgerton Hall, Room 34-101
EECS Colloquium

Abstract

The National Technology Roadmap for Semiconductors speculates on a number of possible "paradigm shifts" that could have a revolutionary impact on the future course of microelectronics. One of these is using organic molecules to form interconnection networks: "To chemically self-construct a 3-D wiring network ... without the sequential generation of "levels of conductors" would be a truly phenomenal development."

That is of course a particularly ambitious vision, but much of the interest in "molecular electronics" stems from the possibility of self-construction or self-assembly. The key idea behind self-assembly is that certain functional groups have a special chemical affinity for other groups and that this can provide a form of molecular recognition. How such elementary recognition processes can be harnessed to implement useful interconnections is a subject of much current research.

In this talk we will primarily focus on the question of what determines the electrical resistance of a molecular wire. We will start by discussing what it means to talk about the "resistance" of something as small as a molecule. Next we will present some recent experimental work that measures the resistance of individual organic molecules by inserting special functional groups at the ends which attach to the surface of a metal like microscopic "alligator clips." We will show how the experimental results can be understood in terms of a simple model, identifying the important factors that affect the shape of the current-voltage characteristics. Finally we will address the question of how molecules can be designed to exhibit specific properties such as rectification or negative differential resistance.