The decline of silicon and the rise of gallium nitride
By John Roberts, CTO, GaN Systems Inc.Semiconductors
Gallium nitride (GaN) is poised to revolutionize the electronics industry as it displaces silicon’s hold on the power electronics market. GaN is a wide band gap semiconductor material that is most well known for its widespread use in LED light bulbs and Blu-ray disks, both high volume consumer applications. It is also currently used in RF power amplifiers because of its inherent advantages in voltage and temperature performance. Large carriers, including Sprint, have already launched GaN-powered towers in several markets.
But where GaN is poised to revolutionize, or perhaps more appropriately ‘evolutionize’, the electronics market is in power switching applications.
Silicon has been used as the material of choice for semiconductors over the past 30 to 40 years, but it has reached its limits in terms of speed, temperature and power handling. Now, GaN offers several critical competitive advantages, in terms of size, weight, efficiency and thermal performance.
The excitement about gallium nitride stems from its unique material and electronic properties. GaN devices offer five key characteristics: high dielectric strength, high operating temperature, high current density, high speed switching and low on-resistance. These characteristics are due to the properties of gallium nitride, which, compared to silicon, offer ten times higher electrical breakdown characteristics, three times the band gap, and exceptional carrier mobility.
This is particularly significant at higher voltages, and the first and most dramatic impact will be for transistors between 600 volts and 1200 volts. In that range, experts are predicting that GaN transistors will make significant gains over silicon over the next 10 years. As an example, a 900V gallium nitride transistor has a switching Figure of Merit (FOM) 6 times better than a silicon transistor. GaN is poised to be the technology to provide 600 volt to 1200 volt semiconductor devices for every type of power conversion, including variable-speed motion control, solid-state lighting, electric vehicle drives, wind and solar converters, uninterruptible power supplies, and eventually the higher power distribution, transmission, and traction markets.
The advantages of GaN are compelling. They include:
* Reduced heat sink requirements
* 80% reduction in system volume and weight
* Much higher efficiency than comparable silicon solutions
* Improved transient characteristics and switching speed
* Reduced electrical noise from smaller system packages
* Reduced electrical noise due to 10x lower recovery charge
* Ability to handle 250°C junction temperatures
* Up to 10x the power density of silicon devices
* High voltage capability
Over the past several years, it has been widely acknowledged within the electronics industry that gallium nitride is a superior technology in terms of potential – and that it is only a matter of time before GaN replaces silicon in certain applications. However, the ability to introduce practical, reliable devices has been a challenge fought vigorously and successfully by companies and research facilities.
One of the factors that will determine how quickly GaN devices gain mass acceptance is simply the time it takes for GaN transistors to demonstrate reliability in industrial or health and safety critical applications. Another is whether new legislation or government initiatives will be created regarding the energy efficiency of power electronic systems.
And then, of course, there is always the issue of economics. One of the key issues preventing a complete revolution of the electronic industry today is that there is currently no cost-effective way to make high quality, large crystals of pure gallium nitride. As a result, the most effective implementations today use silicon carbide base wafers with gallium nitride epitax (GaN-on-SiC). But this approach is also expensive and the leaders in the competitive landscape are targeting unique design and licensed process IP that uses low cost custom silicon base wafers (GaN-on-Si) to achieve low costs that rival conventional silicon technology.
Certain industry sectors are a natural fit for early adoption of this new technology. For cleantech applications, the need for power conversion efficiency is critical. Whenever power has to flow from its source to destination some form of control system is necessary. As new sources of energy are explored – wind, tides, biofuels – the need increasingly arises for ever more efficient controlling systems to link the power into our power grids for distribution to the user. Gallium nitride, with its higher power and temperature capabilities, and hence efficiency, has the potential to create the next generation of power control systems that will make these new sources viable.
And that’s not all. According to the recently published Gallium Nitride (GaN) Semiconductor Devices Market, Global Forecast and Analysis 2012-2022, “Today’s world includes numerous suitable power applications for GaN in several application segments, such as power distribution systems, industrial systems, heavy electrical systems, turbines, heavy machinery, advanced industrial control systems, electro-mechanical computing systems, and so on; also inclusive of several new power applications (clean-tech) such as High-Voltage Direct Current (HVDC), Smart Grid Power Systems, Wind Turbines, Wind Power Systems, Solar Power Systems, Electric and Hybrid Electric Vehicles. Another application sector is ICT, with several communication application segments such as RF, RADAR, and Satellite communication offering huge revenue potentials owing to the unbeatable ability of GaN to operate at high-frequency ranges, including microwave frequencies. The potential market size of these massive applications is currently in trillions, making the total addressable market for the GaN power semiconductors worth billions.”
The Global Forecast and Analysis goes on to say that, “The GaN power semiconductors market is expected to reach $12.60 million by the end of 2012. The phenomenal growth rate of approximately 60 to 80% year-on-year is expected to continue for the following years. The forecasted revenue for GaN power semiconductors is $1.75 billion by end of 2022 (after 10 years) at an explosive CAGR of 63.78% from 2012 to 2022. Apart from power semiconductors, GaN is predominantly used in optosemiconductors, for LEDs and laser diodes. The total GaN semiconductors (including both, power and optosemiconductors) market revenue is expected to reach $2.6 billion by 2022.”
The industry stands on the threshold of change, as we begin an exciting journey of new products and new breakthroughs. And the stakes are extremely high. Currently, there are approximately 36 companies sharing an $18 billion power semiconductor market. Several major players are sitting on the fence; waiting to see how quickly the adoption of this new technology will play out. But for the handful of pioneers out there who continue to climb the learning curve, drive innovation and work towards commercializing their new developments, it’s an exciting time and place to be – on the forefront of this particular technology revolution.
*This article was submitted by GaN Systems Inc. For more information, visit www.gansystems.com