(Invited) Simulation-Driven Optimization of Unconventional Digital Logic Devices

Abstract

Organic thin-film transistor (OTFT) based electronics has been under extensive investigation over the last three decades. Dramatic improvements have been made during this time in terms of basic device performance and stability, yet a formidable challenge remains as to how to disentangle highly complex interplays between the materials properties, device layouts, and final circuit topologies, knowing that there are simply too may possible choices for synthetically diverse, solution-processable organic electronics. In this presentation, we highlight some of our latest researches on robust simulation-based design and realization of novel organic semiconductor logic systems. We first demonstrate the possibility of guided data-level matching at the organic lateral heterojunction ternary inverters that utilize a charge anti-ambipolarity. Here, it is found that controlling the energetic diffusion barrier and minority carrier mobility is the key to obtain the evenly distributed logic values. We then switch the topic to the recently reported 3-D complementary inverter circuits where the p-type and n-type transistors are vertically integrated with a reduced circuit footprint. We focus on the critical effects of the charge injection barriers into the unintentionally doped organic semiconductors, and reveal that the systematic contact efficiency variation leads to a largely improved signal amplification gain, as well as un unusual development of the multi-valued logic behaviors up to the quaternary level. Such results clearly demonstrate that physically-based device simulation has a strong capability of correlating various influential parameters at relevant focus levels, thus paving the way toward a totally predictive engineering paradigm of new materials-based electronics platforms.