Gallium Nitride & Related Wide Bandgap Materials and Devices Dr. Edgar J. Martinez Program Manager DARPATech 2000
GaAs IC Markets 1999 Market $11 Billion 2005 Market $20 Billion Consumers 2% Computers 3% Automotive < 1% Industrial 4% 1999 Communications 87% Fiber Optics 11% Wireless Code 1% Wireless Telephony 70% Satellite 25% Telecommunications 4 % Military 3% ($330M/year) 0 20 40 60 80
GaAs IC Market 1990-1999 1999 SHIPMENT VALUE, US $MILLIONS 1400 1200 1000 800 600 400 200 0 MMIC Analog GaAs Digital GaAs DARPA GaAs Investment MAFET Commercial Wireless 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 100 90 80 70 60 50 40 30 20 10 0 DARPA INVESTMENT, US$MILLIONS Yesterday s military challenges became today s commercial reality
Unmet Challenges in RF Analog Front Ends ❾ Power Density > 1 W/mm ❾ Multi-octave Bandwidth ❾ High Efficiency > 50% ❾ Linearity ❾ Low Noise Figures ❾ Low Phase Noise X Band Ka Band V Band W Band Future DARPA Focus
Electronic Properties of Semiconductor Materials Si (----) GaAs (AlGaAs/ InGaAs) InP (InAlAs/ InGaAs) 4H SiC (----) GaN (AlGaN/ GaN) Bandgap (ev) 1.1 1.42 1.35 3.26 3.49 Electron mobility 1500 8500 10000 700 900 (cm 2 /Vs) Saturated (peak) electron velocity 1 2.1 2.3 2 2.7 (x10 7 cm/s) 2DEG sheet electron density (cm -2 ) Critical breakdown field (MV/cm) Thermal conductivity (W/cm-K) Relative dielectric constant ( εr ) NA <4 x 10 12 <4 x 10 12 NA 20x10 12 0.3 0.4 0.5 2 3.3 1.5 0.5 0.7 4.5 >1.7 11.8 12.8 12.5 10 9.0 P E max 4 g Silicon cannot provide the power-bandwidth product for military applications
III-N N Material Challenges ❾ Substrates difficult to produce ❾ High temperature material growth process ❾ Defect rampant ❾ Low hole mobility ❾ Deep donors and acceptors
Limitations of Today s Solid-State State Devices Intrinsic Thermal Properties I Si FET Microwave Output Power Thermal Management Properties GaAs GaAs GaN GaN Eg Eg (ev) (ev) 1.4 1.4 3.4 3.4 v s (10 s (10 7 7 cm/s) cm/s) 0.8 0.8 2.5 2.5 Output Power Intrinsic Material Electrical Properties V P out = ( I V)/8
Maximum Power (Watt) Current Technology Limitations 100,000 10,000 1000 100 and Potential Improvements 10 1.1 Theoretical Limit for GaN Power Devices Theoretical Limit for GaAs Power Devices Commercial Communications Base Stations COMMERCIAL TELE-COMMUNICATIONS AIR DEFENSE & SURVEILLANCE RADAR EW JAMMERS Power DARPA Technology Goals DBS SHF SATCOM RADAR ARRAY POTENTIAL IVHS 4 2 g s 2 2 2 128π Zn F EHF SATCOM POTENTIAL IVHS EW JAMMERS EHF SATCOM SMART WEAPONS 1 10 100 Frequency (GHz) max = MISSILE TRANSMITTERS EW PHASED ARRAY MCMs E SMART WEAPONS υ Properties Properties GaAs GaAs GaN GaN Eg Eg (ev) (ev) 1.4 1.4 3.4 3.4 v v s (10 s (10 7 7 cm/s)0.8 cm/s)0.8 2.5 2.5 Today s Vacuum Tube Regime Today s Solid State Regime
GaN - A Disruptive Technology State-of-the-art Microwave Power Module Future RF Single Power Chip in an Advanced Package MMIC SSA RF Input 270 V Input HV Power Supply IPC Modulator Vacuum Power Booster BW 18-40 GHz Pout = 40 Watts CW PAE < 30% Vol. > 35 cu in. Weight > 3 lbs RF Output ❾ 10X to 100X output power ❾ Multi-octave bandwidth operation ❾ >35X reduction in volume ❾ >50X reduction in weight GaN PAmp High power chips replace heavy and bulky RF power combiners and Microwave Power Modules
WBG Compound Semiconductors Focus Areas ❾ Material Technology Bulk Crystal Epitaxial Materials Advanced Substrates & Wafers Epitaxial Materials ❾ Device Technology B C Vb2 Electron Devices ❾ Thermal Control & Packages Integrated Circuits
Technical Strategy Comprehensive Effort is Required for Development of Robust Technology MMIC Performance System Performance Packaging & Thermal Management Material Properties & Parameters Device Performance Apply knowledge & Experience from GaAs MMIC Community Leverage from Emerging GaN GaN Commercial Developments Economies of of Scale
Military Applications Multifunction RF Systems Radar Electronic Surveillance High Speed Communications Electronic Warfare Smart Weapons
System Benefits Maximizes bandwidth utilization for multifunctionality Ability to track targets in heavy clutter or in the presence of enemy jamming Reduced system size, cooling requirements, and cost
WBG Semiconductors Optical Benefits UV LEDs BANDGAP ENERGY (ev) 6 5 4 3 2 1 AIN GaN SiC ZnO InN 200nm 310nm UV 460nm Blue 555nm Green 650nm Red Violet Laser Diodes Blue Light Emitting Diodes 2.5 3.0 3.5 4.0 LATTICE CONSTANT (A) White Light
UV Solar Blind Detectors & Current and Future Missile Warning Systems Ground Ground vehicle vehicle self self protection protection Airborne Airborne missile missile threat threat warning warning AAA/MG AAA/MG detection detection and and estimation estimation UV UV search search and and track track Biological Biological agent agent detection detection Engine Engine monitoring monitoring Combustion Combustion control control AN/AAR-47 Ultraviolet Helos Transports AN/AAR-57 Ultraviolet Helos Transports Tactical Today s Technology Bulky, Bulky, Fragile Fragile and and Expensive
Commercial Opportunities for GaN ❾ Traffic lights ❾ Illumination ❾ Automotive ❾ Medicine ❾ Outdoor displays ❾ Mass data storage ❾ Wireless communications GaN Sales ($ Billion) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 2010 > $5 B Market 1 2 3 4 5 6 7 8 9 10 97 98 99 00 01 02 03 04 05 06 Year Data Source: Strategies Unlimited 1997 The The military requirements drive analog and and UV UV detector applications The The commercial opportunities drive optoelectronic applications
Summary ❾ GaN enabling technology for many military applications ❾ Many material and device challenges ❾ Technical strategy requires comprehensive development efforts with many industry and academia partnerships ❾ Significant system benefits anticipated ❾ Commercial interest will not meet military needs DARPA is is in the process of creating new opportunities with WBG semiconductors