November 8, 2012 – Fujitsu Semiconductor says it has built a server power-supply unit with 2.5kW of output power using gallium nitride (GaN) power devices built on a silicon substrate, suitable for high-efficiency power supply units, and will ramp volume production of the GaN-based power devices in late 2013.
Compared with conventional silicon-based power devices, GaN-based power devices have lower on-resistance and can perform high-frequency operations, enabling more compact power supply units with improved conversion efficiency. Efforts to develop GaN-based devices for power applications have gathered momentum in recent months:
- Last year imec produced GaN-on-Si power devices on 200mm wafers, along with the prerequisite fabrication process using standard CMOS processes and tools.
- ON Semiconductor, which recently joined that imec program, is building a GaN processing line in Belgium (formerly owned by AMI Semiconductor).
- Last month Transphorm secured $35M in funding from a Japanese government-backed group and a host of big-name VC firms, to push its GaN power devices.
- A group of partners led by Triquint are combining GaN and silicon carbide (SiC) technology to triple the power handling performance of GaN circuits.
- LED manufacturers who also are working on GaN have been exploring expansion into power electronics to convert underutilized LED fab capacity.
Fujitsu says it has been working on GaN since 2009 and started sampling the technology with select partners in 2011; since then it has been optimizing them for use in power supply units. Key to that work has been collaboration with Fujitsu Laboratories in several key initiatives: process technology for growing high-quality GaN crystals on a silicon substrate, optimizing 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 fruits of those efforts are a prototype server power-supply unit with a GaN-based power-factor-correction circuit that achieves power output of 2.5kW — enough to be suitable for use in high-voltage, large-current applications. The company says it has established a 150mm-wafer volume production line at its Aizu-Wakamatsu plant, and will begin full-scale production of GaN power devices in the second half of 2013.
Efficiency comparison between Fujitsu’s GaN power device and
conventional Si-based power device. (Source: Fujitsu Semiconductor)