GaN Transistors for Efficient Power Conversion

Alex Lidow, Michael de Rooij, Johan Strydom, David Reusch, John Glaser

• Publisher: Wiley
• Year: 2019
• ISBN:
  9781119594420
• Edition: 3
• Topic: Physical Sciences
• Subtopic: Energy

An up-to-date, practical guide on upgrading from silicon to GaN, and how to use GaN transistors in power conversion systems design

This updated, third edition of a popular book on GaN transistors for efficient power conversion has been substantially expanded to keep students and practicing power conversion engineers ahead of the learning curve in GaN technology advancements. Acknowledging that GaN transistors are not one-to-one replacements for the current MOSFET technology, this book serves as a practical guide for understanding basic GaN transistor construction, characteristics, and applications. Included are discussions on the fundamental physics of these power semiconductors, layout, and other circuit design considerations, as well as specific application examples demonstrating design techniques when employing GaN devices.

GaN Transistors for Efficient Power Conversion, 3rd Edition brings key updates to the chapters of Driving GaN Transistors; Modeling, Simulation, and Measurement of GaN Transistors; DC-DC Power Conversion; Envelope Tracking; and Highly Resonant Wireless Energy Transfer. It also offers new chapters on Thermal Management, Multilevel Converters, and Lidar, and revises many others throughout.

• Written by leaders in the power semiconductor field and industry pioneers in GaN power transistor technology and applications
• Updated with 35% new material, including three new chapters on Thermal Management, Multilevel Converters, Wireless Power, and Lidar
• Features practical guidance on formulating specific circuit designs when constructing power conversion systems using GaN transistors
• A valuable resource for professional engineers, systems designers, and electrical engineering students who need to fully understand the state-of-the-art

GaN Transistors for Efficient Power Conversion, 3rd Edition is an essential learning tool and reference guide that enables power conversion engineers to design energy-efficient, smaller, and more cost-effective products using GaN transistors.

1
GaN Technology Overview

1.1 Silicon Power Metal Oxide Silicon Field Effect Transistors 1976–2010

For over four decades, power management efficiency and cost have improved steadily as innovations in power metal oxide silicon field effect transistor (MOSFET) structures, technology, and circuit topologies have kept pace with the growing need for electrical power in our daily lives. In the new millennium, however, the rate of improvement has slowed as the silicon power MOSFET asymptotically approaches its theoretical bounds.

Power MOSFETs first appeared in 1976 as alternatives to bipolar transistors. These majority‐carrier devices were faster, more rugged, and had higher current gain than their minority‐carrier counterparts (for a discussion of basic semiconductor physics, a good reference is [1]). As a result, switching power conversion became a commercial reality. Among the earliest high‐volume consumers of power MOSFETs were AC–DC switching power supplies for early desktop computers, followed by variable‐speed motor drives, fluorescent lights, DC–DC converters, and thousands of other applications that populate our daily lives.

One of the first power MOSFETs was the IRF100 from International Rectifier Corporation, introduced in November 1978. It boasted a 100 V drain‐source breakdown voltage and a 0.1 Ω on‐resistance (R_DS(on)), the benchmark of the era. With a die size over 40 mm² and with a $34 price tag, this product was not destined to supplant the venerable bipolar transistor immediately. Since then, several manufacturers have developed many generations of power MOSFETs. Benchmarks have been set, and subsequently surpassed, each year for 40‐plus years. As of the date of this writing, the 100 V benchmark arguably is held by Infineon with the BSZ096N10LS5. In comparison with the IRF100 MOSFET's resistivity figure of merit (4 Ω mm²), the BSZ096N10LS5 has a figure of merit of 0.060 Ω mm². That is almost at the theoretical limit for a silicon device [2].

There are still improvements to be made in power MOSFETs. For example, super‐junction devices and IGBTs have achieved conductivity improvements beyond the theoretical limits of a simple vertical, majority‐carrier MOSFET. These innovations may still continue for quite some time and certainly will be able to leverage the low‐cost structure of the power MOSFET and the know‐how of a well‐educated base of designers who, after many years, have learned to squeeze every ounce of performance out of their power conversion circuits and systems.

1.2 The Gallium Nitride Journey Begins

Gallium nitride (GaN) is called a wide bandgap (WBG) semiconductor due to the relatively large bonding energy of the atomic components in its crystal structure (silicon carbide [SiC] is the other most common WBG semiconductor). GaN HEMT (High Electron Mobility Transistors) devices first appeared in about 2004 with depletion‐mode radio frequency (RF) transistors made by Eudyna Corporation in Japan. Using GaN‐on‐SiC substrates, Eudyna successfully produced transistors designed for the RF market [3]. The HEMT structure was based on the phenomenon first described in 1975 by Mimura et al. [4] and in 1994 by Khan et al. [5], which demonstrated the unusually high electron mobility described as a two‐dimensional electron gas (2DEG) near the interface between an AlGaN and GaN heterostructure interface. Adapting this phenomenon to GaN grown on SiC, Eudyna was able to produce benchmark power gain in the multigigahertz frequency range. In 2005, Nitronex Corporation introduced the first depletion‐mode RF HEMT device made with GaN grown on silicon wafers using their SIGANTIC® technology.

GaN RF transistors have continued to make inroads in RF applications as several other companies have entered the market. Acceptance outside of this application, however, has been limited by device cost as well as the inconvenience of depletion‐mode operation (normally conducting and requires a negative voltage on the gate to turn the device off).

In June 2009, Efficient Power Conversion Corporation (EPC) introduced the first enhancement‐mode GaN on silicon (eGaN®) fiel...