Epilayer refinements drive record GaN FET power
Japanese chip manufacturer Toshiba says that it has developed a GaN-based field-effect transistor (FET) that emits a record 174 W at 6 GHz, a key frequency band for wireless communication protocols such as WiMAX.
Toshiba, which is describing details of the breakthrough at this week's International Conference on Solid State Devices and Materials (SSDM) in Kobe, Japan, says that the high power output is the result of an optimized epitaxial structure.
The high electron mobility transistor (HEMT) process employed features improvements in AlGaN and GaN layer thicknesses and doping levels, as well as a change in the distance between source and drain electrodes.
Combined with a new gate electrode structure, the various advances cut gate leakage current by 97 percent compared with conventional technology.
The company adds that it is now using a stepper exposure tool instead of electron beam technology in the lithography stage. Toshiba says that the stepper is better suited to mass production of the devices.
The FET actually consists of four GaN chips, which is said to minimize heating effects that are detrimental to device performance.
Following further refinements of the transistors, probably to push the output power even higher, Toshiba plans to release samples next year.
After years of being touted as a key technology for broadband wireless communications, GaN now appears to be on the brink of commercialization.
You can hear more about the emerging GaN markets and the drive to commercialize wide-bandgap technology for RF semiconductors at this year's Key Conference, which has been organized by the publisher of Compound Semiconductor.
A series of talks on the technology includes contributions from Eudyna Devices, Nitronex Corporation, Lockheed-Martin Radar Systems, Strategies Unlimited and HRL Microelectronics. For more details, check out the conference technical program.
