Scaling limits of organic digital circuits

The effect of device scaling on organic circuits' performance was studied. Particularly, the influence of contact resistance on the static and the dynamic behavior of the circuits was investigated. For that purpose, an analytical model describing the voltage transfer characteristics (VTCs) and the propagation delay was developed. Using the model, it was shown that for OTFTs with channel lengths of less than 10 mu m the contact resistance has negative influence on both, the static noise margin (SNM) and the propagation delay. Moreover, the model is in a good agreement with experimentally measured data. Scaling the lateral dimensions of the transistors down to few mu m limits the circuit performance due to contact effects, and the 1-10 MHz frequency range operation required by some applications can only be achieved by reducing the specific contact resistance, rho c, 10-100 times. This need for rho c reduction highlights the importance of improving charge injection in organic transistors that can usually be achieved by contact doping like in inorganic electronics. (C) 2013 Elsevier B. V. All rights reserved.