Interfacial charge transfer in nanoscale polymer transistors
Interfacial charge transfer plays an essential role in establishing the relative alignment of the metal Fermi level and the energy bands of organic semiconductors. While the details remain elusive in many systems, this charge transfer has been inferred in a number of photoemission experiments. We present electronic transport measurements in very short channel (L < 100 nm) transistors made from poly(3-hexylthiophene) (P3HT). As channel length is reduced, the evolution of the contact resistance and the zero gate voltage conductance are consistent with such charge transfer. Short channel conduction in devices with Pt contacts is greatly enhanced compared to analogous devices with Au contacts, consistent with charge transfer expectations. Alternating current scanning tunneling microscopy (ACSTM) provides further evidence that holes are transferred from Pt into P3HT, while much less charge transfer takes place at the Au/P3HT interface.
KeywordsOrganic semiconductors band alignment charge transfer organic field-effect transistor scanning tunneling microscopy
- Gundlach, D. J.; Royer, J. E.; Park, S. K.; Subramanian, S.; Jurchescu, O. D.; Hamadani, B. H.; Moad, A. J.; Kline, R. J.; League, L. C.; Kirillov, O.; Richter, C. A.; Kushmerick, J. G.; Richter, L. J.; Parkin, S. R.; Jackson, T. N.; Anthony, J. E. Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits. Nat. Mater. 2008, 7, 216–221.CrossRefPubMedADSGoogle Scholar
- Donhauser, Z. J.; McCarty, G. S.; Bumm, L. A.; Weiss P. S. High resolution dopant profiling using a tunable AC scanning tunneling microscope. In Characterization and Metrology for ULSI Technology: 2000 International Conference; Seiler, D. G. et al., Eds.; American Institute of Physics: New York, 2001, pp. 641–646.Google Scholar
- Kelly, K. F.; Donhauser, Z. J.; Mantooth, B. A.; Weiss, P. S. Expanding the capabilities of the scanning tunneling microscope. In NATO ASI Series II: Mathematics, Physics, and Chemistry; Vilarinho, P.; Rosenwaks, Y.; Kingon, A., Eds.; Springer: New York, 2005, pp. 153–171.Google Scholar