Chemistry and Materials Science Thesis Defense: Development and Optimization of Electric-Double-Layer Gated Transistors Based on Low-Dimensional Materials: Gate-All-Around InAs Nanowire Arrays and Graphene Channels

Chemistry and Materials Science Thesis Defense
Development and Optimization of Electric-Double-Layer Gated Transistors Based on Low-Dimensional Materials: Gate-All-Around InAs Nanowire Arrays and Graphene Channels

Wyatt Morrell
Rochester Institute of Technology

Abstract:
Electric-double-layer (EDL) gating is a promising alternative to conventional gating methods for field-effect transistors (FETs), with potential applications spanning current logic, future logic, and neuromorphic computing architectures. This technique employs mobile ions in an electrically insulating but ionically conductive medium to generate strong local electric fields at the gate-to-channel interface, achieving field magnitudes on the order of 1 V/nm. These intense local fields enable significant charge carrier accumulation in the semiconducting channel, positioning EDL gating as a strong candidate for device applications. In this study, we investigate the use of low-dimensional channel materials, including two-dimensional graphene and one-dimensional InAs nanowires, in EDL-gated FETs. InAs nanowires, with electron mobilities approximately 30 times higher than silicon, offer a compelling alternative channel material for next generation electronic devices.
For the first time, we report the development of an EDL gate-all-around (GAA) vertical InAs nanowire (NW) array geometry grown directly on a monolayer graphene film. This device leverages the flexibility of EDL gating to gate the vertical NW array, maximizing the high intrinsic electron mobility of InAs. The free-standing NWs grown on monolayer graphene present a unique geometry with significant scaling potential and compatibility with current logic architectures. Additionally, we demonstrate the fabrication and optimization of FETs based on two-dimensional materials within the RIT cleanroom. This process, initially demonstrated on mechanically exfoliated graphene, is extensible to other 2D films such as transition metal dichalcogenides (TMDs), including exfoliated and epitaxially grown layers. These advancements pave the way for future exploration of neuromorphic and brain-inspired computing devices based on these material systems.

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