Date of Award

Fall 2025

Language

English

Embargo Period

11-26-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Nanoscale Science and Engineering

Program

Nanoscale Engineering

First Advisor

Woongje Sung

Committee Members

Woongje Sung, Seung Yup Jang, Nathaniel Cady, Ji Ung Lee, Bongmook Lee

Keywords

4H Silicon Carbide, MOSFET, Power Device, TCAD, 3D, 1.2kV

Subject Categories

Electronic Devices and Semiconductor Manufacturing | Nanoscience and Nanotechnology | Nanotechnology Fabrication | Power and Energy

Abstract

This research contributes to the advancement of 1.2 kV 4H-Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) through the development and implementation of sophisticated three-dimensional Technology Computer-Aided Design (3D TCAD) methodologies. These advanced simulation techniques enable comprehensive evaluation of innovative unit cell architectures that remain inaccessible to conventional two-dimensional (2D) TCAD approaches. By leveraging these 3D simulation capabilities, this work facilitates significant improvements in both the performance and reliability of next-generation wide-bandgap power devices.

Power devices convert electrical energy between different forms throughout the power grid making them essential in applications ranging from personal electronics, electric vehicles, renewable energy systems, industrial equipment, and data centers. Growing demand for these applications, combined with the drive toward a more sustainable electrical grid, requires developing increasingly efficient power devices that minimize resistance and energy losses during voltage control, current regulation, and switching operations. Historically, power devices were primarily fabricated using silicon, but the push for greater efficiency has driven exploration of wide bandgap materials offering superior performance characteristics. Among these alternatives, 4H-SiC has emerged as one of the most promising candidates, demonstrating exceptional capabilities that have already enabled its successful commercialization, especially 1.2 kV rated MOSFETs.

Persistent challenges hinder 4H-SiC MOSFET advancement, most notably the poor channel mobility stemming from defects at the 4H-SiC epitaxial layer/SiO2 gate oxide interface. These defects create electron trapping sites and scattering centers that significantly degrade carrier transport, increasing specific on-resistance (Ron,sp) and switching losses. Despite extensive efforts to improve this interface, channel mobility remains below 30 cm²/V·s.

Alternative approaches to improve the electrical characteristics of 1.2kV 4H-SiC MOSFETs involve device and layout optimization. However, these approaches were previously constrained by the limitations of 2D TCAD simulations, which cannot fully evaluate novel device architectures with non-linear device geometries. The development and deployment of 3D TCAD simulation now enables the comprehensive evaluation of these novel device designs prior to fabrication, accelerating the optimization of 1.2kV SiC MOSFETs.

This work represents a critical step forward in power device optimization. By deploying 3D TCAD simulations, researchers can now evaluate numerous device architectures to identify and better optimize critical regions in these devices prior to fabrication. This capability enables the development of more efficient power devices essential for meeting the growing energy demands of modern society while advancing sustainability goals across multiple technological sectors.

License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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