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oai:www.ideals.illinois.edu:2142/129696 2026-02-05 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

application/pdf en text Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01 The student, Hanwool Lee, accepted the attached license on 2025-04-17 at 01:00. The student, Hanwool Lee, submitted this Dissertation for approval on 2025-04-17 at 01:08. This Dissertation was approved for publication on 2025-04-18 at 16:08. DSpace SAF Submission Ingestion Package generated from Vireo submission #21812 on 2025-10-19 at 19:53:17 Expanding electronics beyond silicon with wide-bandgap, 2D, and ferroelectric materials Lee, Hanwool 2025-04-18 Zhu, Wenjuan Zhu, Wenjuan Lyding, Joseph W Rakheja, Shaloo Zhao, Yang 2D Materials Ferroelectrics Wide-bandgap Electronics Chemical vapor deposition MoTe2 GaN Reconfigurable eng This dissertation explores the advancement of microelectronics through novel materials, including two-dimensional (2D) materials, ferroelectric materials, and wide-bandgap semiconductors. These emerging materials enable new functionalities, improve energy efficiency, and enhance stability for various applications. Chapter 1 provides background information for this dissertation, including a brief review of 2D materials, particularly transition metal dichalcogenides (TMDCs). Ferroelectric materials and their device applications are discussed. Additionally, wide-bandgap semiconductors and their advantages are introduced, with a particular focus on gallium nitride (GaN). Chapter 2 explores non-volatile reconfigurable transistors with four-mode operation. Utilizing the strong polarization of epitaxially grown scandium aluminum nitride (ScAlN), a single device can function as an n-type, p-type, always-on, or always-off transistor. The feasibility of these transistors for logic gate applications is demonstrated. Additionally, non-volatile latch operation is presented using van der Waals materials, including ferroelectric copper indium thiophosphate (CIPS) and molybdenum ditelluride (MoTe2). Ferroelectric field-effect transistor (FeFET) with metal-ferroelectric-metal-insulator-semiconductor (MFMIS) structure enables stable memory operation. Using these FeFETs, non-volatile sequential logic operation is demonstrated through a simple latch circuit. Chapter 3 demonstrates the wafer-scale synthesis of MoTe2 using di-tert-butyl telluride ((C4H9)2Te) as the tellurium precursor, along with molybdenum hexacarbonyl (Mo(CO)6) and sputtered molybdenum (Mo) as molybdenum precursors. The successful wafer-scale growth of both 1T' and 2H phases of MoTe2 is presented, with various characterization results confirming the uniformity, phase selectivity, and high crystallinity of the synthesized material. Chapter 4 investigates GaN-based high-electron-mobility transistors (HEMTs) for high-temperature applications. Dielectric stack optimization, gate recess structures, and p-GaN/AlGaN/GaN heterostructures are explored to achieve stable operation up to 500 °C. Optimizing the dielectric stack enhances the breakdown field and device lifetime, while the gate recess and p-GaN/AlGaN/GaN heterostructure enable enhancement-mode operation with improved threshold voltage stability at high temperatures. Chapter 5 concludes this dissertation by summarizing key findings and outlining directions for future research. By integrating emerging materials with innovative design strategies, these studies advance next-generation electronic devices and facilitate their practical implementation in semiconductor technology. 2025-05 Thesis https://hdl.handle.net/2142/129696 Copyright 2025 Hanwool Lee Electrical & Computer Eng Electrical & Computer Engr University of Illinois Urbana-Champaign Ph.D. Dissertation