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Abstract <p>This study presents a comprehensive evaluation of AlGaN/GaN-based high electron mobility transistors (HEMTs) with various passivation schemes, providing critical insights for device optimization. HfO<sub>2</sub>-passivated devices exhibit superior breakdown characteristics, achieving a remarkable breakdown voltage (<i>V</i><sub>br</sub>) of 788 V, which confirms the advantage of high-<i>k</i> dielectrics in enhancing voltage withstand capability. In contrast, SiO<sub>2</sub>-passivated HEMTs exhibit optimal radio frequency (RF) performance, including the highest cut-off frequency (&#xa0;<i>f</i><sub><i>T</i></sub>), which is attributed to their lower parasitic capacitance, making them ideal for high-frequency applications. This reflects a fundamental trade-off between breakdown strength and frequency response in HEMT devices. To overcome this limitation, a dual-passivation approach is investigated. Type-A exhibits superior DC performance, with higher drain saturation current (<i>I</i><sub>dss</sub>), transconductance (<i>g</i><sub>m</sub>), and <i>V</i><sub>br</sub>, owing to the stronger gate control and electric field modulation provided by the high-<i>k</i> HfO<sub>2</sub> top layer. Both dual-layer passivation schemes significantly enhance <i>V</i><sub>br</sub> (~798 V for Type-A, ~797 V for Type-B) compared to single-layer passivation. In RF analysis, Type-B (Si<sub>3</sub>N<sub>4</sub> on top, HfO<sub>2</sub> below) outperforms Type-A. Although Type-A exhibits higher <i>f</i><sub><i>T</i></sub> up to 0.4 µm, thicker HfO<sub>2</sub> increases parasitic capacitances, degrading GFP, TFP, and GTFP. In contrast, Type-B improves with thicker Si<sub>3</sub>N<sub>4</sub>, validating the advantage of placing a low-<i>k</i> on top of a high-<i>k</i> dielectric. Considering composite FOMs (TFP, GFP, GTFP, V<sub>EA</sub>, A<sub>V</sub>), Type-B achieves superior overall RF performance.</p>

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Performance Trade-Offs and Optimization of Single and Dual-Layer Passivation AlGaN/GaN HEMTs with Double-Deck Gate Field Plate

  • 期刊论文

  • 发表日期：

    2026年2月16日

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  • Pichingla Kharei,
  • Achinta Baidya,
  • Niladri Pratap Maity

摘要

Abstract

This study presents a comprehensive evaluation of AlGaN/GaN-based high electron mobility transistors (HEMTs) with various passivation schemes, providing critical insights for device optimization. HfO2-passivated devices exhibit superior breakdown characteristics, achieving a remarkable breakdown voltage (Vbr) of 788 V, which confirms the advantage of high-k dielectrics in enhancing voltage withstand capability. In contrast, SiO2-passivated HEMTs exhibit optimal radio frequency (RF) performance, including the highest cut-off frequency ( fT), which is attributed to their lower parasitic capacitance, making them ideal for high-frequency applications. This reflects a fundamental trade-off between breakdown strength and frequency response in HEMT devices. To overcome this limitation, a dual-passivation approach is investigated. Type-A exhibits superior DC performance, with higher drain saturation current (Idss), transconductance (gm), and Vbr, owing to the stronger gate control and electric field modulation provided by the high-k HfO2 top layer. Both dual-layer passivation schemes significantly enhance Vbr (~798 V for Type-A, ~797 V for Type-B) compared to single-layer passivation. In RF analysis, Type-B (Si3N4 on top, HfO2 below) outperforms Type-A. Although Type-A exhibits higher fT up to 0.4 µm, thicker HfO2 increases parasitic capacitances, degrading GFP, TFP, and GTFP. In contrast, Type-B improves with thicker Si3N4, validating the advantage of placing a low-k on top of a high-k dielectric. Considering composite FOMs (TFP, GFP, GTFP, VEA, AV), Type-B achieves superior overall RF performance.