Suppression of Short-Channel Effects in AlGaN/GaN HEMTs Using SiN_x Stress-Engineered Technique

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• Short-channel effects (SCEs) degrade the performance of advanced transistors.
• AlGaN/GaN high-electron-mobility transistors (HEMTs) are crucial for high-frequency applications.
• Passivation layers play a key role in device stability and performance.

Purpose of the Study:

• To investigate the novel application of SiNₓ stress-engineering for SCE suppression in AlGaN/GaN HEMTs.
• To analyze the underlying physical mechanisms responsible for the observed improvements.
• To demonstrate the potential for enhanced device performance and reliability.

Main Methods:

• Fabrication of AlGaN/GaN HEMTs with varying SiNₓ passivation stress.
• Characterization of device electrical performance, including drain-induced barrier lowering (DIBL).
• Analysis of barrier height modulation and quasi-Fermi level behavior under bias.

Main Results:

• Compressive SiNₓ stress significantly enhances the heterojunction barrier height.
• Devices with compressive SiNₓ passivation exhibited substantially lower DIBL factors (e.g., 2.25 mV/V at 5V).
• Minimal degradation in transconductance, subthreshold swing, and leakage current was observed with increasing drain bias.

Conclusions:

• SiNₓ stress engineering is a viable technique for mitigating SCEs in GaN HEMTs.
• The enhanced barrier height is key to improved device stability and performance.
• This approach offers a pathway to high-performance, reliable GaN-based RF electronics.