Characterization of silicon-based molecular resonant tunneling diodes with scanning tunneling microscopy

In recent years, substantial progress has been made in the emerging field of molecular electronics. In particular, metal-molecule-metal junctions have been widely studied. In this paper, charge transport through molecule-semiconductor junctions is considered. The presence of the energy band gap in semiconductors provides opportunities for resonant tunneling through individual molecules, leading to interesting effects such as negative differential resistance (NDR). Furthermore, by doping the substrate, the majority charge carrier can be tailored, thus allowing asymmetry to be intentionally designed into the current-voltage characteristic. Through judicious choice of the molecular species, the bias voltage of the NDR can also be controlled. By demonstrating these effects on the Si(100) surface, semiconductor-based molecular electronic devices have the potential of being directly interfaced to conventional silicon integrated circuit technology. This paper summarizes recent theoretical and experimental work on silicon-based molecular resonant tunneling diodes.