Ph.D. Final Defense - Dnyanesh Deepak Sarawate

Title: Electric-Field-Driven Ion Trapping and Tunable Relaxation Kinetics in Two-dimensional Transistors for Edge Computing Abstract: Two challenges that modern electronics face include processing sensor data directly on local devices (i.e., edge computing) and protecting hardware from reverse engineering. These two applications demand different memory behaviors: processing time-dependent signals requires a short-term, fading memory, whereas protecting hardware requires programmable doping that persists without constant power. One way to achieve time-dependent memory is through the use of ions in an electric-double-layer (EDL). EDL gating provides ultra-high interfacial capacitance density (µF/cm²) by drifting mobile ions in an electrolyte to a semiconductor surface under an applied voltage. This dissertation first characterizes the time-dependent pulse dynamics of a well-studied PEO:LiClO₄ electrolyte on graphene and WSe₂ transistors. In a dual-gate configuration, pulsed inputs generate a fading memory for processing ECG signals, where 30/30 ms pulse timing at 305 K maintains baseline stability (+1.57% net retention) and current modulation up to 21%. Next, this work demonstrates the use of electric fields generated by the EDL (~V/nm) to trigger localized chemistry in a custom solid polymer electrolyte, enabling both programmable relaxation kinetics and non-volatile doping in 2D transistors. This custom copolymer, poly(DEAEMA-co-PEGMA), is synthesized to undergo an electric-field-triggered Menshutkin crosslinking reaction. In graphene FETs, +5 V programming induces persistent n-type shifts. Low-temperature readouts (T = 200 K) freeze mobile bulk ions to isolate trapped interfacial charge, confirming a sheet carrier density of ~10¹² cm⁻² with ≈80% retention over seven weeks; control devices with no crosslinker show no such retention. Finally, applying this electrolyte to WSe₂ transistors yields a programmable temporal element. Increasing the programming bias f