Whenever a company considers a significant change in the architecture, components, or suppliers used in the design and creation of its semiconductor-driven products, it must first confirm that the performance delivered is as promised. After this, the need to validate reliability and costs becomes the primary concern. As in the case of materials in any industry, how do you evaluate something that is completely new? What are the new rules and benchmarks? And if you have to rely on suppliers for the most in-depth knowledge, how do you know who to trust?
These questions are of particular interest in the wide-bandgap (WBG) semiconductor industry that still remembers the historic under-delivery of the promises of the SiC (silicon carbide) Schottky diode products more than ten years ago. These products experienced current leakage that gradually increased over time until the device catastrophically failed. Although companies eventually recovered from the field failures and product recalls, this experience made their customers even more suspect about new materials such as gallium nitride (GaN) when it arrived on the scene a few years later with its own promises. This extreme caution was particularly difficult to overcome in industries such as automotive and industrial that are dominated by large global brands that are technologically conservative.
GaN power transistor companies face this challenge: how do you overcome the staunch reluctance of companies to use new materials like GaN? With that reluctance predicated on mistakes that you didn’t make?
GaN costs and reliability — the early days
The truth of comparing GaN to silicon was clouded by several factors.
When GaN power transistors first arrived in the marketplace nearly 10 years ago, they were seen as more costly and their reliability was unknown compared to silicon for use in applications such as power supplies, wireless power, and envelope tracking. On a simple transistor-to-transistor basis, GaN was significantly more expensive resulting from low volume production and low yields. As an immature product, the industry was also not sure how to prove the reliability of GaN devices. It was unclear if the JEDEC MOSFET test standard was appropriate or sufficient. With low shipments of product, there was also limited field data available.
How do we define costs when talking about GaN in the semiconductor industry?
The common practice of purchasing departments is to evaluate the value of a transistor on its purchase price, with lower price seen as better. As a new technology, designers and business executives didn’t know how to frame and evaluate the questions of cost and value for GaN. The significant performance improvements were clear, but their value was not.
Depending on the industry, the appropriate definition of cost can range from the simple bill of materials (BOM) to the need for a more holistic total cost of ownership (TCO) calculation.
- For consumer power adapters and chargers, the measure of cost is set by the BOM via the consumer price. It is also important to note that the system design of many chargers today require power densities greater than that which can be achieved with silicon MOSFETs, which completely eliminates the relevance of the silicon versus GaN cost question.
- In data centers, true cost calculations need to reflect cost savings from GaN energy efficiencies in the CAPEX and OPEX of data center operations, as well as the increased efficiencies from enhanced system services, such as more memory per server rack that is delivered with increased power supply density.
- In electric vehicle production, manufacturing savings can result from the use of smaller batteries in vehicles using energy efficient GaN technology in their onboard chargers and traction inverters. Additionally, the original battery size could be used to deliver even greater driving range, making the vehicle more valuable in the marketplace.
Reliability must answer the question: “How long will my system or product operate as intended in a specific environment?” In the automotive industry this timeframe (mission profile) may be 20 years, while in consumer electronics it may be significantly shorter at 5 years. Regardless of the timespan, the goal for any material in any product design is to achieve a FIT metric of less than 1 (number of failures for every one billion hours). In calculating FIT for a circuit board in power electronics, the FIT metrics of all the components are factored into the lifetime rating of the final system.
When GaN products were first offered for sale in 2010-2014, transactions were usually done privately, with NDAs in place even to merely receive data sheets — and many times the product did not even meet the datasheet specifications.
GaN Systems took a contrary approach to the industry by providing datasheets publicly on its own website and offering product for sale through industry standard catalog distribution without any limiting conditions. That was a start, and in the ensuing years, GaN proved itself.
Today’s proof points around GaN technology
The behaviors of companies today show that they now understand the cost dynamics of GaN technology and have confidence in its proven reliability. GaN power semiconductors are produced at high volume with a CAGR of more than 50% — and that is expected to increase over the next several years. Nearly all major semiconductor companies now recognize that a power GaN portfolio offering is necessary to remain relevant in the marketplace.
- More than 50 different models and millions of units of GaN power chargers are currently in the marketplace in response to the popularity of consumer demand. Numerous brands can access the high volume production they require, and believe in the cost/price point and reliability levels they can deliver to their customers.
- Siemens, with its known focus on quality, reliability, and production for its industrial and Industry 4.0 customers, has offered GaN-based motor drives for the past two years, including the Simatic Micro-Drive product line.
- In the world of high performance electric vehicle auto racing, cars must operate flawlessly under extreme conditions for long periods of time. BrightLoop has become the sole supplier of GaN-based DC to DC converters for the ETCR racing circuit.
- In the ecosystem of industries known as High Rel (aerospace, radar, satellite), where reliability is non-negotiable, GaN Systems is collaborating with several industry leaders, including Teledyne, on new high performance and energy efficient applications.
GaN Technology in the Near Future
The momentum for the increased use of GaN, along with the customer confirmation of its cost effectiveness and reliability, will continue to accelerate across the industries where leading brands already have products in the marketplace that meet or exceed industry standards (industrial motor drives, DCDC converters, and power chargers/adapters). Additional markets are set to embrace GaN in 2020 and 2021 with new applications in areas where high quality audio is desired (smart speakers) and also where high power density and efficiency are needed — commercial data centers, 5G base stations, and renewable energy storage systems in smart homes.
— Paul Wiener is vice president of strategic marketing at GaN Systems