Abstract
Metal-organic molecule-semiconductor junctions are controlled not only by the molecular properties, as in metal-organic molecule-metal junctions, but also by effects of the molecular dipole, the dipolar molecule-semiconductor link, and molecule-semiconductor charge transfer, and by the effects of all these on the semiconductor depletion layer (i.e., on the internal semiconductor barrier to charge transport). Here, we report on and compare the electrical properties (current-voltage, capacitance-voltage, and work function) of large area Hg/organic monolayer-Si junctions with alkyl and alkenyl monolayers on moderately and highly doped n-Si, and combine the experimental data with simulations of charge transport and electronic structure calculations. We show that, for moderately doped Si, the internal semiconductor barrier completely controls transport and the attached molecules influence the transport of such junctions only in that they drive the Si into inversion. The resulting minority carrier-controlled junction is not sensitive to molecular changes in the organic monolayer at reverse and low forward bias and is controlled by series resistance at higher forward bias. However, in the case of highly doped Si, the internal barrier is smaller, and as a result, the charge transport properties of the junction are affected by changing from an alkyl to an alkenyl monolayer. We propose that the double bond near the surface primarily increases the coupling between the organic monolayer and the Si, which increases the current density at a given bias by increasing the contact conductance.
Original language | English |
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Pages (from-to) | 10270-10279 |
Number of pages | 10 |
Journal | Journal of Physical Chemistry C |
Volume | 114 |
Issue number | 22 |
DOIs | |
Publication status | Published - 10 Jun 2010 |
Funding
US-Israel Binational Science Foundation; Israel Science Foundation, ISF; Lise Meitner - Minerva Center for Computational Chemistry; Monroe and Marjorie Burk Fund for Alternative Energy Studies; National Science Foundation [DMR-0705920]; Princeton MRSEC of the National Science Foundation [DMR-0819860]; Dutch Ministry of Economic Affairs [WSC.6972]; Azrieli FoundationD.C. and A.K. thank the US-Israel Binational Science Foundation, D.C. and L.K. thank the Israel Science Foundation, ISF, through its Converging Technology and Centre of Excellence programs, L.K. thanks the Lise Meitner - Minerva Center for Computational Chemistry, and D.C. also thanks the Monroe and Marjorie Burk Fund for Alternative Energy Studies for partial support. At the Weizmann Institute, this work was made possible in part by the historic generosity of the Harold Perlman family. A.K. thanks the National Science Foundation (DMR-0705920) and the Princeton MRSEC of the National Science Foundation (DMR-0819860). H.Z. thanks NanoNed, funded by the Dutch Ministry of Economic Affairs (project WSC.6972) for financial support. O.Y. thanks the Azrieli Foundation for the award of an Azrieli Fellowship. D.C. holds the Sylvia and Rowland Schaefer Chair in Energy Research.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- General Energy
- Surfaces, Coatings and Films
- Physical and Theoretical Chemistry