Fabrication and characterization of novel cross point structures for molecular electronic integrated circuits

Molecular electronic devices have the potential to dramatically increase the density and performance of integrated circuits. In order to realize this potential, reliable and scalable fabrication of nanoscale molecular electronic devices is essential. The authors have developed a new type of cross point structure in which the molecules are self-assembled between two metallic electrodes separated by an aluminum oxide layer. The gap between the electrodes is only a few nanometers wide and is defined by the aluminum oxide layer thickness, so it can be adjusted to match the length of the molecules with high (subnanometer) precision. This fabrication method applies to the study of transport properties of single molecules and at the same time is compatible with processes used in electronic industry, so that it may be used in the future to integrate molecular devices with silicon-based integrated circuits. Since the molecular self-assembly is the last step of the process, damage to molecules can be minimized. The authors have achieved a relatively high yield of high-quality support structures even at this early stage of technology development. Preliminary experimental data for electron transport through self-assembled oligo-phenylene-ethynylene-based molecules are compatible with the general theory of sequential single-electron tunneling.