Molecular Electronics and Biochemical Sensing

Peter Grutter, McGill University

A central issue in nanoelectronics is the role of electrical contacts.

In the first part of this talk I will present recent results obtained by our group on atomically defined contacts between two metal surfaces using a combined UHV STM/AFM/FIM system. One contacting wire is a surface atomically characterized by STM, while the second contact is made a field ion microscopy (FIM) characterized tip (see figure). I will present results using this technique to study W tip- Au(111) sample interactions in the regimes from weak coupling to strong interaction. The obtained results are discussed in the context of dissipation in non-contact AFM as well as electrical contact formation in molecular electronics.

In the second part I will concentrate on cantilever based biochemical sensing. We have investigated a model system, alkanethiol adsorption on a Au coated microfabricated AFM cantilever, to understand the origin of stress in this self assembled monolayer (SAM) / sensor platform. We find that the kinetics of formation, and the resulting structure, of the SAM are strongly influenced both by the underlying surface structure and the alkanethiol impingement rate. These measurements allow us to elucidate the origin and magnitude of surface stress resulting from different molecular recognition events. Optimizing the sensor response requires efficient charge transfer to the Au layer --an unexpected conceptual connection to contact issues in molecular electronics!

Host: Michael Roukes