Stable Organic Monolayers on Oxide-Free Silicon/Germanium in a Supercritical Medium: A New Route to Molecular Electronics.
Oxide-free Si and Ge surfaces have been passivated and modified with organic molecules by forming covalent bonds between the surfaces and reactive end groups of linear alkanes and aromatic species using single-step deposition in supercritical carbon dioxide (SCCO2). The process is suitable for large-scale manufacturing due to short processing times, simplicity, and high resistance to oxidation. It also allows the formation of monolayers with varying reactive terminal groups, thus enabling formation of nanostructures engineered at the molecular level. Ballistic electron emission microscopy (BEEM) spectra performed on the organic monolayer on oxide-free silicon capped by a thin gold layer reveals for the first time an increase in transmission of the ballistic current through the interface of up to three times compared to a control device, in contrast to similar studies reported in the literature suggestive of oxide-free passivation in SCCO2. The SCCO2 process combined with the preliminary BEEM results opens up new avenues for interface engineering, leading to molecular electronic devices.
†Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576.|‡Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602.
Sreenivasa Reddy
SR
Puniredd
†Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576.
Sundaramurthy
S
Jayaraman
†Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576.
Sai Hooi
SH
Yeong
‡Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602.
Cedric
C
Troadec
†Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576.
M P
MP
Srinivasan
ballistic electron emission microscopy; covalent molecular assembly; molecular electronics; nonoxidized silicon surface; organic monolayer; supercritical carbon dioxide