Innovative Power Amplifier Gate Thermal Management for Active Radar Systems
Navy SBIR FY2008.2

Sol No.: Navy SBIR FY2008.2
Topic No.: N08-170
Topic Title: Innovative Power Amplifier Gate Thermal Management for Active Radar Systems
Proposal No.: N082-170-0513
1600 Adams Drive
Suite 112
Menlo Park, California 94025-1449
Phone: (650) 688-5760
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Abstract: This Phase-I SBIR MDA Proposal proposes the use of a new class of diamond-seeded solid-state material system for the manufacture of virtually all heat-generating solid-state electronics in X-band and Ballistic Missile Defense radar components and systems. In this proposal wherein much preliminary (MDA-funded) work has been demonstrated hitherto by the authors, Gallium Nitride-on-SiC power amplifiers in X-band radar are replaced with GaN-on-Diamond power amplifiers to enable nearly total and immediate heat extraction from the device's active region. This proposal is specifically focused on exfoliating GaN FET epitaxy from SiC (rather than Si), and attaching the GaN FET to a CVD Diamond substrate. Free-standing polycrystalline CVD diamond - nature's most efficient thermal conductor - enables nearly perfect heat extraction from a "hot" device, owing to the extreme thermal conductivity of diamond (GaAs, Si, and SiC are 35W/m/K, 150W/m/K and 390W/m/K respectively; diamond ranges from 1200-2000 W/m/K depending on quality). In the proposed scheme, 5+ W/mm of output RF power are expected to be measured from the GaN FET-on-Diamond device while operating at half the temperature of GaN-on-SiC devices. The semiconductor-on-diamond technology proposed here may be applied to Si, GaAs, GaN, SiC, SiGe, etc. at up to 8" in wafer diameter.
Benefits: It is expected that GaN-on-diamond power amplifiers deployed in a Naval X-band radar system will result in (i) a 50-80% reduction in thermal management devices/space volume, and (ii) a 250-800% increase in heat dissipation performance while maintaining LRU form factor - when compared to traditional technology such as GaN-on-SiC or InP. The boosted heat-dissipation performance will also be reflected in the transistor's maximum output power density, gain, frequency bandwidth, and power amplification efficiency when compared to traditional (Si, GaAs, GaN, and SiC) technology. GaN-on-diamond based devices cost the same as traditional semiconductor-on-semiconductor technology owing to a) the low cost of CVD polycrystalline diamond ($200-$400 per 4" diamond wafer), and b) the availability of large diameter diamond substrates (6" & 8") compared to standard GaN and SiC (3" and 4"). The proposed solution requires no moving parts, liquids, or gases. Group4's proposed technology is expected to impact other markets including Wireless base-stations, WLAN, Radar, ultra-bright White/Blue/Green LEDs, Laser Diodes, Household ovens, etc. that are worth over $1bn.