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INDUSTRY ENGINEERED SUBSTRATES A GaN-on-Diamond


Wafer of HEMT arrays fabricated by AFRL


diamond Keeping cool with


By sucking heat from GaN HEMTs better than other substrates, diamond enables transistors to operate at higher ambient temperatures and have reduced finger spacing


BY FELIX EJECKAM FROM ELEMENT SIX TECHNOLOGIES


THANKS TO A TREMENDOUS SET OF INTRINSIC CHARACTERISTICS, GaN-based RF transistors are setting a new benchmark for solid-state device performance. But that does not mean that they are fulfilling their true potential, because the heating in channel degrades device lifetime when the RF chip operates near its peak power output.


To address this weakness, our team (initially Group4 Labs, acquired by Element Six in 2013) began in 2003 to develop a higher thermal conductivity substrate that more effectively extracts heat out of a transistor based device: directly deposited CVD diamond.


This development will allow GaN-on-


diamond devices to replace the more common GaN-on-SiC devices and traveling wave tubes in defence radar and electronic warfare systems. What’s more, commercial systems such as cellular base stations, weather and communications satellites and power devices may be able to deliver greater energy efficiency, while being lighter and


Distribution Statement A (Approved for Public Release, Distribution Unlimited) October 2014 www.compoundsemiconductor.net 41


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