Molecular Electronics: New Approaches towards Molecular Switches.

GUSTAVO M. MORALES; WEI YOU; MARIA IAVARONE; GORAN KARAPETROV; SHENGWEN YUAN; LUPING YU

Mar del Plata, Argentina,

Simposio; 4th Latin-American Symposium on Scanning Probe Microscopy – IV LASPM; 2007

The technology of CMOS-based semiconductor industry has advanced at an incredible rate over the past decades. This phenomenon is usually cited as Moore’s Law, which states the fact that transistor density on a silicon chip doubles every 18 months. However, CMOS devices are reaching its fundamental physics limit, and the cost associated with constructing the facilities to manufacture these devices is prohibitively high. For that reason, many researchers are exploring molecular alternatives to CMOS-based computing paradigm. Assemblies of chemically synthesized nano-objects or single molecules are proposed as alternatives to conventional CMOS-based circuits. The field of molecular electronics seeks to use individual molecules to perform electronic functions now performed by semiconductor materials. The heart of the semiconductor industry is the semiconductor switch; a combination of them can perform all desired computational functions. Then, molecular electronic components that switch between high and low resistance states are crucial for the further development of the molecular electronic field. A molecular switch is a single molecule that can be interchanged between two distinct “on” and “off” states. In this work we describe two different approaches to attain switch effect using single molecules. The first one involve conformational motions controlled by the interelectrode applied electric field (via molecular motion), and the second a resonant tunneling mechanism through electronic states of a transition-metal complex (via electrostatic effects). The study of the switching effect was performed on two families of molecules (A and B in the figure) by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) at different temperatures.