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Enhanced Operational Characteristics Attained by Applying HfO2 as Passivation in AlGaN/GaN High-Electron-Mobility
Jun-Hyeok Choi1, Woo-Seok Kang1, Dohyung Kim1
1Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 04620, Republic of Korea.
Micromachines
|June 28, 2023
Summary
This study optimized AlGaN/GaN high-electron-mobility transistors (HEMTs) using hybrid passivation. A novel HfO2/Si3N4 structure improved breakdown voltage and maintained radio frequency (RF) performance, enhancing Johnson
Area of Science:
- Materials Science
- Semiconductor Device Physics
- Electrical Engineering
Background:
- Aluminum Gallium Nitride/Gallium Nitride (AlGaN/GaN) high-electron-mobility transistors (HEMTs) are crucial for high-power and high-frequency applications.
- Passivation layers are essential for protecting HEMTs and improving their operating characteristics.
- Traditional silicon nitride (Si3N4) passivation has limitations that necessitate exploring alternative or hybrid approaches.
Purpose of the Study:
- To investigate the impact of Hafnium Dioxide (HfO2) as a passivation layer on AlGaN/GaN HEMTs.
- To compare the operating characteristics of HEMTs with Si3N4, HfO2, and a hybrid HfO2/Si3N4 passivation structure.
- To optimize a hybrid passivation structure for enhanced breakdown voltage and radio frequency (RF) performance.
Main Methods:
- Device fabrication and characterization of AlGaN/GaN HEMTs with different passivation layers (Si3N4, HfO2, hybrid HfO2/Si3N4).
- Derivation of modeling parameters from measured data of Si3N4-passivated HEMTs for simulation reliability.
- Systematic analysis and comparison of breakdown voltage, frequency characteristics, and Johnson's figure-of-merit (JFM) for various passivation schemes.
Main Results:
- The HfO2-only passivation improved breakdown voltage by 19% but degraded RF characteristics.
- A hybrid HfO2/Si3N4 structure with optimized Si3N4 thickness (350 nm) enhanced breakdown voltage by 15%.
- The optimized hybrid structure maintained RF performance, leading to a 5% improvement in JFM compared to basic Si3N4 passivation.
Conclusions:
- Hybrid passivation using HfO2 and Si3N4 offers a promising approach to simultaneously improve breakdown voltage and RF performance in AlGaN/GaN HEMTs.
- Optimizing the thickness of the passivation layers in a hybrid structure is critical for achieving desired device characteristics.
- The developed hybrid passivation strategy provides a pathway for next-generation high-performance electronic devices.
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