Technologies for Low Power Density Phased Array Radars

This Phase-II SBIR proposal proposes the use of a new class of diamond-seeded solid-state material system for the manufacture of virtually all packaged intense heat-generating solid-state electronics in X-band and Ballistic Missile Defense radar components and systems. In this proposal wherein much preliminary (also 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 focused on producing a 3” GaN-on-Diamond FET wafer, as well as 5 W/mm GaN-on-Diamond FET devices. Polycrystalline free standing 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, the device’s active epitaxial layers are removed from their original host substrate and transferred to a specially treated low-cost CVD diamond substrate using a proprietary low-cost manufacturable scheme. The semiconductor-on-diamond technology proposed here may be applied to Si, GaAs, GaN, SiC, SiGe, etc. at up to 8” in wafer diameter. BENEFIT: It is expected that GaN-on-diamond power amplifiers deployed in an X-band and BMD 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.