Invention Description
Ultrawide-bandgap (UWBG) semiconductors are of interest for high-voltage and high-power applications. AlN offers a wide bandgap, high critical electric field, and high thermal conductivity, making it an attractive material for UWBG application. These properties may also result in reduced power losses, high breakdown voltages, and improved thermal performance compared with conventional semiconductor materials. However, practical implementation of AlN power devices remains challenging due to limitations associated with low free-electron concentrations, defect-related compensation, contact formation, and leakage. Further, AlN layers fabricated on non-native substrates can have high crystalline defects and dislocations which may limit performance, reliability, and efficiency. While single-crystal AlN substrates can reduce dislocation density and improve carrier properties relative to AlN-on-sapphire layers, their cost and availability remain limiting factors.
Researchers at Arizona State University have developed ultrawide-bandgap aluminum nitride (AlN) trench metal-oxide-semiconductor field-effect transistors (MOSFETs) on single-crystal AlN substrates for power electronics. These devices combine a homoepitaxial AlN-on-AlN platform with a trench-gate architecture that extends gate control into the device structure. Further, the architecture of these MOSFETs helps them achieve improved channel control, reduced on-resistance, and increased current capacity. Devices with varying trench depths were tested, and the deeper-trench devices provided stronger electrostatic control of the channel, suppressing off-state leakage and improving current modulation.
These advanced AlN trench MOSFETs on single-crystal substrates offer superior high-power performance through optimized gate trench depths for power electronics.
Potential Applications
- High-power electronic devices and power transistors
- Electric vehicle powertrains and charging infrastructure
- Industrial motor drives and power conversion systems
- RF and microwave power amplifiers
- Renewable energy systems including solar inverters and wind turbine converters
- Aerospace and defense power electronics
Benefits and Advantages
- 20-fold increase in on/off current ratio
- Improved thermal conductivity for stable operation at high temperatures
- Greater current capability supporting demanding power loads
- Potential to outperform traditional SiC and GaN technologies
- Twofold improvement in maximum transconductance
- 1.5 times higher maximum drain current compared to shallower trenches
- Superior drain current and breakdown electric field on single-crystal AlN substrates
- Improved gate control and reduced leakage currents
- Lower on-resistance for improved efficiency
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