Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

Committee Chair

Fat Duen Ho

Committee Member

Aleksandar Milenkovic

Committee Member

John Stensby

Committee Member

Mark Tillman

Committee Member

B. Earl Wells

Subject(s)

Spline theory., Metal oxide semiconductor field-effect transistors--Mathematical models., Computer-aided design--Software.

Abstract

This dissertation presents the first ever application of quintic splines in the development of a dual-gate Metal Oxide Semiconductor Field Effect Transistor (MOSFET) model based on the well-known drift-diffusion system of differential equations. The techniques and methodologies presented advance the current state of the art in this particular area by implementing improved two-dimensional numerical techniques and limiting the use of common accuracy reducing assumptions intended to decrease semiconductor equation complexity and simulation execution time. This results in the first known two-dimensional physics based model that uses this numerical technique, is valid in all regions of operation, includes Non-Quasi Static transient behavior, accounts for intrinsic/extrinsic device capacitance effects, determines frequency response, and allows researchers to determine the effects of gate oxide thickness imperfections and applied gate voltage disparities on device performance. A complimentary Computer Aided Device, or CAD, software package was also developed to demonstrate model capability and validity. This CAD software provides a user interface for entering device physical dimensions, material properties and external transient terminal voltage behavior. When executed, the CAD software simulates n-channel and p-channel device performance as well as selected circuits: CMOS inverter, ring oscillator, cross coupled oscillator and differential amplifier. The resulting data product is presented in a collection of one- and two-dimensional plots as well as relational tabular listings. This data product includes steady state and Non-Quasi Static currents, potential distribution, two-dimensional carrier concentration profiles, electric field contours, charge based capacitances and frequency response. Additionally, this work does not assume ideal device symmetry nor identically applied voltages at the individual gate terminals. This unique feature adds realism to the model and allows researchers to study the effects of true-to-life fabrication variances on device performance.

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