Low Leakage Current and High Breakdown Field AlGaN/GaN MIS-HEMTs Using PECVD-SiNx as a Gate Dielectric

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Gallium Nitride (GaN)-based High Electron Mobility Transistors (HEMTs) are crucial for high-power and high-frequency applications.
• Metal-Insulator-Semiconductor (MIS) structures are essential for enhancing HEMT performance and reliability.
• Optimizing gate dielectric properties is key to unlocking the full potential of GaN HEMTs.

Purpose of the Study:

• To investigate the impact of silicon nitride (SiNx) gate dielectric deposition parameters on AlGaN/GaN HEMTs.
• To explore the role of ammonia (NH3) flow and in-situ nitrogen (N2) plasma treatment in improving device performance.
• To demonstrate the effectiveness of plasma-enhanced chemical vapor deposition (PECVD) SiNx as a gate dielectric for GaN-based HEMTs.

Main Methods:

• Deposition of SiNx films using plasma-enhanced chemical vapor deposition (PECVD).
• Varied ammonia (NH3) flow rates during SiNx deposition.
• In-situ N2 plasma surface treatment prior to SiNx deposition.
• Characterization of Metal-Insulator-Semiconductor (MIS) HEMTs, including gate leakage current, ON/OFF drain current ratio, and breakdown field.

Main Results:

• Optimized NH3 flow during SiNx deposition drastically reduced gate leakage current (3 orders of magnitude) and improved the ON/OFF drain current ratio (2 orders of magnitude).
• The breakdown field of MIS-HEMTs increased by 69% with optimized NH3 flow.
• In-situ N2 plasma treatment further enhanced DC performance, achieving a gate leakage current of 10^-9 mA/mm and an ON/OFF ratio of 10^9 by reducing interface states.

Conclusions:

• Ammonia flow during PECVD SiNx deposition is a critical parameter for optimizing AlGaN/GaN MIS-HEMT performance.
• In-situ N2 plasma surface treatment provides further significant improvements in device characteristics.
• PECVD-SiNx is a highly promising gate dielectric for advanced GaN-based power electronics.