Fujitsu Semiconductor Europe (FSEU) has achieved high output power of 2.5kW in server power-supply units equipped with gallium-nitride (GaN) power devices built on a silicon substrate. Using GaN technology in power supply applications has helped to enhance power efficiency and reduce the carbon footprint. Compared with conventional silicon-based power devices, GaN-based power devices feature lower on-resistance and the ability to perform high-frequency operations.
As these characteristics improve the conversion efficiency of power supply units and make them more compact, this technology is suitable not just for servers but for a broad range of applications including solar inverters, battery chargers or electric vehicles.
Fujitsu Semiconductor plans to commercialise GaN power devices on a silicon substrate, increasing the diameters of the silicon wafers and enabling low-cost production. The company began work on GaN technology in 2009 and began providing specific power-supply-related partners with sample GaN power devices in 2011. Since then, Fujitsu has worked on optimising the devices for use in power supply units. Fujitsu will start volume production of the GaN power devices by the second half of 2013.
Fujitsu Semiconductor collaborated closely with Fujitsu Laboratories on several key technical initiatives to achieve this technological progress, including the development of the process technology for growing high-quality GaN crystals on a silicon substrate. The collaboration also delivered device technologies, such as optimising the design of electrodes to control the rise of on-resistance during switching, and devising a circuit layout for power supply units that can support high-speed switching of GaN-based devices.
The results enable Fujitsu Semiconductor to achieve conversion efficiency that exceeds the performance of conventional silicon devices by using a GaN power device in a power-factor-correction circuit. For example, Fujitsu Semiconductor created a prototype server power-supply unit incorporating a power-factor-correction circuit based on GaN technology that achieved output power of 2.5kW. This impressive performance makes GaN power devices suitable for use in high-voltage, large-current applications.
Fujitsu Semiconductor has established a mass-production line for 6-inch wafers at its Aizu-Wakamatsu plant and will begin full-scale production of GaN power devices in the second half of 2013. By offering GaN power devices ptimized for customer applications and technology support for circuit designs, Fujitsu Semiconductor will enable the development of low-loss, compact power supply units for a wide range of uses.