Date of Award

2-1-2025

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Electrical and Computer Engineering

Keywords

dual-phase operation; early-stage detection; field-effect transistor; sensitivity; sensor technology

Supervisor

Arezoo Emadi

Rights

info:eu-repo/semantics/openAccess

Abstract

Traditional transistor design approaches to increase chip density and device performance predominantly involve increasing the width-length ratio of planar structures and developing complex three-dimensional structures via width folding and vertical stacking. In transistor-based sensor design, trends for improving sensitivity emphasize an extended sensing area to facilitate a greater number of analyte interactions. However, these approaches are limited within traditional rectangular topology and complicate fabrication. In contrast, this work introduces transistor designs that establish unique channel configuration criteria for unconventional topologies. Three approaches are presented in this work to strategically modulate transistor performance and include modifications in the sensing area, width-length ratio, and electric field distribution. The proposed topologies challenge traditional transistor design criteria to maintain a consistent channel length while expanding the functional gate area. Among the topologies introduced are the Cross and the Octagram, designed to improve the sensitivity of open-gate junction field-effect transistors. Original implementations of these designs are fabricated using organic field-effect transistors and are characterized for the first time against existing reference topologies, evaluated based on performance metrics relevant to their functionality as sensors. The findings demonstrate the Octagram’s potential for low-power applications due to its low threshold voltage. The Cross-channel configuration achieves at least a fourfold increase in current response compared to the conventional rectangular design with the same branch width-length ratio. Its transconductance also exhibits enhancements of up to 5.5 and 4.8 times greater than the conventional rectangular references of the same branch width-length ratios and open gate area, respectively. Modifications to the size, number, geometry or biasing configuration further enhance the Cross’s tunability, highlighting its capacity for improving sensor linearity. The simplicity of the proposed design approaches presented in this work enables their application across various field-effect transistor technologies with similar expected performance improvements without complicating fabrication.

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