| PhD Seminar

Name of the Speaker: Ms. Seethalakshmi Iyyakutty (EE22D035)
Guide: Dr. NanditaDasGupta
Venue: ESB-244 (Seminar Hall)
Date/Time: 25th Aug 2025 (Monday), 2:30 PM
Title: Gallium Nitride based Four Quadrant Switch Technology for Power Electronic Applications

Abstract :

Four-Quadrant Switches (FQS), also known as bidirectional switches, are capable of conducting current and blocking voltage in both forward and reverse directions. Traditionally, FQS configurations have been implemented using silicon (Si) MOSFETs and are widely employed in power converter systems for applications such as bidirectional motor control, battery management, and electric propulsion systems in space. However, Gallium Nitride (GaN)-based High Electron Mobility Transistors (HEMTs) offer superior performance over their silicon counterparts due to their superior material properties. GaN-based FQS technology has garnered significant research interest, particularly for applications in electric vehicles, industrial motor drives, and advanced power electronics. Realizing FQS functionality using GaN requires normally-OFF or enhancement-mode HEMTs. Several methods for realizing normally-OFF HEMTs have been reported in the literature, including cascode configurations, recessed-gate structures, and p-GaN gate architectures.

In this work, TCAD-based modelling of p-GaN-based FQS is presented for the first time. The simulation successfully captures the symmetric transfer characteristics and bidirectional operation of the device. A detailed analysis of key design parameters, including aluminium mole fraction, magnesium doping (NMg), gate metal work function and pGaN layer thickness is conducted to understand their impact on device performance. Additionally, fabrication challenges specific to p-GaN-based structures are addressed, and a viable approach for realizing GaN-based FQS devices in power electronic applications is proposed.