| AVS 57th International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuM |
| Session: | Contacts and Transport |
| Presenter: | A.E. Schuckman, Texas A&M University |
| Authors: | A.E. Schuckman, Texas A&M University K.M. Webb, Texas A&M University L.M. Perez, Texas A&M University M. Jurow, Hunter College of the City University of New York L.H. Yu, National Institute of Standards and Technology C.M. Drain, Hunter College of the City University of New York J.G. Kushmerick, National Institute of Standards and Technology J.D. Batteas, Texas A&M University |
| Correspondent: | Click to Email |
Porphyrins are stable, highly conjugated compounds and the choice of metal ion and substituents bound to the macrocycle as well as other effects such as chemical surrounding and cluster size modulate the electronic and photonic properties of the molecule. Porphyrins and their derivatives are relatively non-toxic, and due to their very rich photo- and electro-chemistry as well as their small HOMO-LUMO gaps, this makes them outstanding candidates for use in molecularly-enhanced electronic applications.
For this study, the transport properties of self-assembled zinc coordinated tri-pyridyl porphyrin thiol islands inserted into a dodecanethiol matrix on Au(111) were investigated using scanning tunneling microscopy (STM) and cross-wire inelastic tunneling spectroscopy (IETS). The zinc porphyrin thiol islands observed by STM exhibited reversible bias-induced switching at high surface coverage due to the formation of Coulomb islands of ca. 10 nm diameter driven by porphyrin aggregation. Low temperature measurements (~ 4 K) from crossed-wire junctions verified the appearance of a Coulomb staircase and blockade which was not observed for single molecules of this compound or for the analogous free base. Scanning probe lithography via nanografting has been implemented to fabricate nanoscale patterns of the zinc porphyrin thiols on Au surfaces and ultimately ~ 10 nm islands which is the optimal size for the observed switching effect.