Microinverters and power optimizers are widely utilized in modern solar panels to maximize energy efficiency and conversion. Such topologies and implementations usually require a minimum of 25 years of lifetime, which is becoming a critical challenge for market adoption. Low-voltage gallium nitride (GaN) power devices (VDS rating < 200 V) are a promising solution and are being used extensively by an increasing number of solar manufacturers.

In this article, a test-to-fail approach is adopted and applied to investigate the intrinsic underlying wear-out mechanisms of GaN transistors. The study enables the development of physics-based lifetime models that can accurately project the lifetimes under the unique demands of various mission profiles in solar applications.

How2Power
August, 2023
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Transient voltage overshoot is a common phenomenon in GaN high electron mobility transistors (HEMTs) under high slew rate switching conditions. The dynamic parametric instability under such stress is a critical concern for GaN applications. This work, for the first time, accurately characterized the evolution of dynamic on-resistance (R_DS(on)) in GaN HEMTs under repetitive voltage overshoot up to billions of switching cycles. The dynamic R_DS(on) increase was found to be the dominant device degradation under overvoltage switching. Such findings were obtained from a high-frequency, repetitive, unclamped inductive switching (UIS) test with active temperature control and accurate in-situ R_DS(on) monitoring. A physics-based model was proposed to correlate the dynamic R_DS(on) drift with the peak overvoltage, and a good agreement with experimental data was achieved. This model was further used to project the lifetime of GaN HEMTs. For 100 V rated GaN HEMTs switched under 100 kHz and 120 V spikes, the model projects less than 10% dynamic R_DS(on) shift over 25 years of continuous operation. This work addresses the major concerns of overvoltage switching reliability of GaN HEMTs and provides new insights of the electron trapping mechanism.

IEEE Xplore
Ruizhe Zhang, Ricardo Garcia, Robert Strittmatter, Yuhao zhang, Shengke Zhange
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In this episode of Spirit: Behind the Screen, Spirit Electronics CEO Marti McCurdy chats with EPC’s CEO Alex Lidow and Marketing Director Renee Yawger about the progress of GaN. They discuss GaN’s performance under high radiation as well as the extensive testing, failure modes and device lifespan detailed in EPC’s Phase 15 reliability report. With the full potential of GaN still to be explored and new EPC products releasing frequently, including new half-bridge drivers, low-side drivers and full power stage, GaN is especially useful in New Space and commercial space applications.

Spirit: Behind the Screen
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Modern solar panels are demanding increasingly higher power density and longer operating lifetimes. Solar applications including power optimizers and panels with built-in microinverters are becoming the prevailing trend for an increasing number of solar customers, where low voltage GaN power devices (V_DS < 200 V) are extensively used.

Bodo’s Power Systems
May, 2023
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A few simple thermal management guidelines can help conduct heat away from GaN FETs. Enhancement-mode gallium nitride (eGaN) FETs offer high power-density with ultra-fast switching and low on-resistance, all in a compact form factor. However, the power levels these high-performance devices provide can be limited by extreme heat-flux densities. If not managed properly, the generated heat can compromise reliability and performance. Fortunately, chip-scale packaging for eGaN FETs can be leveraged at the board-side and the backside (i.e., case) to better dissipate heat.

Power Electronics Tips
February, 2022
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A roundtable discussion with GaN industry experts hosted by Bodo’s Power Systems. Guests included:

1. Alex Lidow, CEO and co-founder of Efficient Power Conversion
2. Doug Bailey, Vice President Marketing & Applications Engineering at Power Integrations
3. Dilder Chowdhury, Director, Strategic Marketing, Power GaN Technology at Nexperia
4. Tom Ribarich, Sr. Director Strategic Marketing at Navitas Semiconductor

Recently, Efficient Power Conversion (EPC) did a series of tests to take eGaN^® FETs beyond their data sheet limits to quantify the effects of large amounts of overstress voltage and current and the results are published here for the first time.

Bodo’s Power Systems
May, 2021
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Enhancement-mode gallium nitride (eGaN) FETs have demonstrated excellent thermomechanical reliability in actual operation in the field or when tested according to AEC or JEDEC standards. This is because of the inherent simplicity of the “package,” the lack of wire bonds, dissimilar materials, or mold compound. Recently, an extensive study of underfill products was conducted to experimentally generate lifetime predictions. A finite element analysis at the end of this section explains the experimental results and generates guidelines for selection of underfill based on key material properties.

Bodo's Power
March, 2021
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In last month’s Safety & Compliance column in How2Power, “WBG Semiconductors Pose Safety And EMI Challenges In Motor Drive Applications,”[1]Kevin Parmenter made some assertions about the difficulties of using SiC, and to a lesser extent GaN, power semiconductors in large motor-drive applications. This commentary is a response to that article, showing that GaN can be a game changer in low-voltage integrated motors.

How2Power
February, 2021
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Standard qualification testing for semiconductors typically involves stressing devices at-or-near the limits specified in their data sheets for a prolonged period of time, or for a certain number of cycles. The goal of qualification testing is to have zero failures out of a large group of parts tested. By testing parts to the point of failure, an understanding of the amount of margin between the data sheet limits can be developed, but more importantly, an understanding of the intrinsic failure mechanisms of the semiconductor can be found.

IEEE Power Electronics Magazine
December, 2020
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An automotive application using GaN power devices in high volume is lidar(light detection and ranging) for autonomous vehicles. Lidar technology provides information about a vehicle’s surroundings, thus requiring high accuracy and reliability to ensure safety and performance. This article will discus a novel testing mechanism developed by EPC to test eGaN devices beyond the qualification requirements of the Automotive Electronics Council (AEC) for the specific use case of lidar.

Power Systems Design
December, 2020
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Gallium nitride (GaN) power devices have been in volume production since March 2010 and have established a remarkable field-reliability record. An automotive application using GaN power devices in high volume is lidar (light detection and ranging) for autonomous vehicles. Lidar technology provides information about a vehicle’s surroundings, thus requiring high accuracy and reliability to ensure safety and performance. This article will discuss a novel testing mechanism developed by Efficient Power Conversion (EPC) to test eGaN devices beyond the qualification requirements of the Automotive Electronics Council (AEC) for the specific use case of lidar.

eeNews Europe
July 30, 2020
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Why these chips are gaining ground, and what still needs to be addressed. Suppliers of gallium nitride (GaN) and silicon carbide (SiC) power devices are rolling out the next wave of products with some new and impressive specs. But before these devices are incorporated in systems, they must prove to be reliable.

Semiconductor Engineering
June, 2020
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Gallium Nitride (GaN) power devices have been in volume production since March 2010 with remarkable field reliability. This article details how by testing parts to the point of failure an understanding of the amount of margin between the data sheet limits can be developed, but more importantly, an understanding of the intrinsic failure mechanisms can be found. By knowing the intrinsic failure mechanisms, the root cause of failure, and the device’s behavior over time, temperature, electrical or mechanical stress, the safe operating life of a product can be determined over a more general set of operating conditions.

Power Systems Design
March 3, 2020
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It’s okay to start using gallium-nitride (GaN) devices in your new designs. GaN transistors have become extremely popular in recent years. These wide-bandgap devices have been replacing LDMOS transistors in many power applications. For example, GaN devices are broadly being adopted for new RF power amplifiers used in cellular base stations, radar, satellites, and other high-frequency applications. In general, their ability to endure higher voltages and operate at frequencies well into the millimeter-wave (mmWave) range have them replacing traditional RF power transistors in most amplifier configurations.

Electronic Design
November, 2019
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GaN technology has matured to a point where it can challenge traditional silicon technology.  Gallium nitride(GaN)-on-silicon low voltage power devices have enabled many new applications since commercial availability began in 2010. New markets, such as light detection and ranging (LiDAR), envelope tracking, and wireless power, emerged due to the superior switching speed of GaN. These new applications have helped develop a strong supply chain, low production costs, and an enviable reliability record. All of this provides adequate incentive for the more conservative design engineers in applications, such as DC/DC converters, AC/DC converters, and automotive to start their evaluation process. In this article, the factors leading to the rapid acceleration of the adoption rate are explored.

Electronics Weekly
January 2019
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Gallium nitride (GaN) power transistors designed for efficient power conversion have been in production for seven years. New markets, such as light detection and ranging, envelope tracking, and wireless charging, have emerged due to the superior switching speed of GaN. These markets have enabled GaN products to achieve significant volumes, low production costs, and an enviable reliability reputation. All of this provides adequate incentive for the more conservative design engineers in applications such as dc-dc converters, ac-dc converters, and automotive to start their evaluation process. So what are the remaining barriers to the conversion of the US$12 billion silicon power metal-oxide-semiconductor field-effect transistor (MOSFET) market? In a word: confidence. Design engineers, manufacturing engineers, purchasing managers, and senior management all need to be confident that GaN will provide benefits that more than offset the risk of adopting a new technology. Let's look at three key risk factors: supply chain risk, cost risk, and reliability risk.

IEEE Spectrum
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The previous installment in this series focused on the physics of failure surrounding thermo-mechanical reliability of EPC eGaN wafer level chip-scale packages. A fundamental understanding of the potential failure modes under voltage bias is also important. This installment will provide an overview of the physics of failure associated with voltage bias at the gate electrode of gallium nitride (GaN) field effect transistors (FETs). Here we look at the case of taking the gate control voltage to the specified limit and beyond to investigate how eGaN FETs behave over a projected lifetime.

Planet Analog
Chris Jakubiec
November 29, 2016
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The first three installments in this series covered field reliability experience and stress test qualification of EPC’s enhancement-mode gallium nitride (eGaN) field effect transistors (FETs) and integrated circuits (ICs). Excellent field reliability that was documented is the result of applying stress tests covering the intended operating conditions the devices will experience within applications. Of equal importance is understanding the underlying physics of how eGaN devices will fail when stressed beyond intended operating conditions (e.g. datasheet parameters and safe operating area). This installment will take a deeper dive into the physics of failure centered around thermo-mechanical reliability of eGaN wafer level chip-scale packages (WLCSP).

Planet Analog
Chris Jakubiec
September 7, 2016
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