Inducing an inversion layer in organic semiconductors is a highly nontrivial, but critical, achievement for producing organic field-effect transistor (OFET) devices, which rely on the generation of inversion, accumulation, and depletion regimes for successful operation. In recent years, a major milestone was reached: an OFET was made to successfully operate in the inversion-mode for the first time. Here, we develop a pulsed bias technique to characterize the dopant type of any organic material system, without prior knowledge or characterization of the material in question. We use this technique on a pentacene/PTCDI heterostructure and thus deduce that pentacene is n-doped by impurities. Additionally, through tip-induced band-bending, we generate inversion, depletion, and accumulation regimes over a 20~nm radius, three monolayer thick n-doped pentacene island. Our findings demonstrate that nanometer-scale lateral extent and thickness are sufficient for an OFET device to operate in the inversion regime.
@article{arxiv.2008.01562,
title = {Charge carrier inversion in a doped thin film organic semiconductor island},
author = {Zeno Schumacher and Rasa Rejali and Megan Cowie and Andreas Spielhofer and Yoichi Miyahara and Peter Grutter},
journal= {arXiv preprint arXiv:2008.01562},
year = {2021}
}
Comments
Updated manuscript with additional data and findings