1.7kV fully-vertical GaN trench MOSFET with nitrogen ion-implanted guard rings

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Vertical Gallium Nitride (GaN) trench MOSFETs are crucial for high-power electronics.
• Achieving high breakdown voltage (BV) and normally-off operation simultaneously remains a challenge.
• Effective edge termination techniques are essential for device reliability and performance.

Purpose of the Study:

• To present a high-performance fully vertical GaN trench MOSFET on a GaN substrate.
• To introduce a novel edge termination strategy using selective nitrogen ion-implanted guard rings (GRs).
• To demonstrate a simplified fabrication process for high-voltage GaN devices.

Main Methods:

• Fabrication of a fully vertical GaN trench MOSFET on a GaN substrate.
• Implementation of selective nitrogen ion implantation to create semi-insulating regions for guard rings (GRs).
• Utilizing Technology Computer-Aided Design (TCAD) simulations to analyze electric field distribution.

Main Results:

• Achieved a high breakdown voltage (BV) of 1715 V.
• Demonstrated normally-off operation with a threshold voltage (Vth) of 4.1 V.
• Obtained a specific on-resistance (Ron,sp) of 5.3 mΩ·cm² and 262 Ω·mm.
• TCAD simulations confirmed effective electric field redistribution by p-GaN rings, mitigating field crowding.

Conclusions:

• The selective ion-implantation guard ring (GR) technique offers an efficient and simple method for edge termination in vertical GaN trench MOSFETs.
• This approach enables the realization of high-performance 1.7 kV-class vertical GaN trench MOSFETs.
• The developed device exhibits excellent voltage-blocking capability and normally-off characteristics.