Toward Nanoscale Organic Tunnel Field-Effect Transistors with Small Subthreshold Swing and High On-State Current: A Computational Design Based on Two-Dimensional Covalent-Organic Frameworks

We report a computational study on the possibility of designing nanoscale organic tunnel field-effect transistors (OTFETs) with a subthreshold swing (SS) much smaller than 60 mV/dec and on-state current (I-on) much larger than that of conventional organic field-effect transistors. The OTFETs are designed on the basis of two-dimensional metallophthalocyanine covalent-organic frameworks (2D MPc-COFs) by employing first-principles and quantum-transport approaches in the ballistic-transport regime. The designed OTFETs with architecture of the van der Waals heterojunction manifest themselves with SS as small as 21 mV/dec and I-on as large as 887.5 mu A/mu m. These devices outperform most tunnel field-effect transistors reported in the literature and fulfill the IRDS (International Roadmap for Devices and Systems) requirement for both high-performance (HP) and low-power (LP) devices. We reveal that 2D MPc-COFs with moderate band gaps are highly required to optimize the device performance. This study provides an insight into the promising application of 2D COFs beyond conventional organic materials in the rational design of HP and LP nanoscale OTFETs.