AVS 51st International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+NS-ThM

Paper OF+NS-ThM5
Room Temperature Negative Differential Resistance Measured through Molecular Monolayers Adsorbed to Silicon Surfaces with Ultra-high Vacuum Scanning Tunneling Microscopy

Thursday, November 18, 2004, 9:40 am, Room 304C

Session: Molecular Electronics
Presenter: N.P. Guisinger, Northwestern University
Authors: N.P. Guisinger, Northwestern University
R. Basu, Northwestern University
M.E. Greene, Northwestern University
A.S. Baluch, Northwestern University
M.C. Hersam, Northwestern University
Correspondent: Click to Email
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, a continued study of 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 room temperature negative differential resistance (NDR).@footnote 1@ In this study, the ultra-high vacuum scanning tunneling microscope was used to probe charge transport through two different molecular monolayers adsorbed to the Si(100) substrate. I-V measurements were taken on monolayers of TEMPO and cyclopentene for both degenerately doped n-type and p-type Si(100) substrates. Initial I-V measurements through the TEMPO monolayer exhibited a suppression of NDR behavior relative to previously reported transport through isolated molecules.@footnote 1@ I-V measurements were also taken on isolated cyclopentene molecules, as well as on cyclopentene monolayers. The cyclopentene monolayers similarly exhibited a suppression of the observed NDR behavior relative to transport through isolated molecules. For both molecular monolayers, the suppression of the peak-to-valley ratio (PVR) has been measured to exceed a 47 percent reduction compared to observed PVRs of isolated molecules. The resulting NDR suppression in both monolayers indicate that the local environment surrounding the molecules strongly influences charge transport. In addition to molecular monolayers, initial studies of transport through isolated TEMPO molecules adsorbed to both degenerate and non-degenerate Si(111) will be discussed. @FootnoteText@ @footnote 1@N. P. Guisinger, M. E. Greene, R. Basu, A. S. Baluch, and M. C. Hersam, "Room temperature negative differential resistance through individual molecules on silicon surfaces," Nano Letters, 4, 55 (2004).