Atom to Circuit Modeling Strategy for 2D Transistors

Abstract

Two-dimensional materials are now being considered as viable options for CMOS (complementary metal-oxide-semiconductor) technology extension due to their diverse electronic and opto-electronic properties. However, introduction of any new material in the process integration phase of technology development in the semiconductor industry is an expensive and time-consuming affair. It is also difficult to select an appropriate 2D material from the plethora without assessing their performance at circuit level. Thus, first-principles-based multiscale models that enable systematic performance evaluation of emerging 2D materials at device and circuit levels solely from their crystallographic information are in great demand. In this thesis, such an atom-to-circuit modeling framework, addressing three different levels of abstraction (viz. material, device, and circuit), has been demonstrated. Firstly, the model was developed for a van der Waal s heterostructure (vdWH) based all-2D metal-insulator-semiconductor field-effect transistor (MISFET), comprising of vertically stacked semi-metallic graphene, insulating hexagonal boron nitride (hBN) and semiconducting monolayer molybdenum disulphide (MoS2). Our physics-based compact model demonstrates the effects of band gap opening in graphene due to its sublattice symmetry breaking interactions with underlying hBN layer. This apart, proposed model captures the effects of semiconductor doping and the band gap variation of graphene at device and circuit levels. The model equations were thereafter implemented in a professional circuit simulator using its Verilog-A interface to facilitate design and simulation of integrated circuits. Secondly, the scope of the proposed model was further extended to capture the inertia of the charge carrier in 2D transistors operating at very high frequencies, typically greater than its intrinsic cut-off frequency...