本論文於同一 GaN 平臺上成功製作增強型鐵電 HEMT 與增強型電荷捕陷 HEMT。承襲先前以高鋁含量電荷捕陷層 Hf0.78Al0.22O 之經驗，本論文將閘極堆疊優化為低鋁含量 Hf0.92Al0.08O。其閾值電壓位移 (ΔVₜₕ) 為 6.2 V，並確保持續穩定的偏壓後操作。
在鐵電元件部分，本研究採用 10 nm Al2O3/25 nm AlScN 雙層閘極介電層製備 AlScN MIS-HEMT。該元件之峰值跨導為 88 mS·mm⁻¹，最大飽和電流達 356.9 mA·mm-1；其將可調閾值電壓視窗擴展至 12.47 V 以上，正向極化狀態下 Vₜₕ 約為 0.8 V。相較於傳統耗盡型 HEMT，本元件之導通電流與跨導幾乎無損耗，顯示結構設計得當且性能優異。
綜合上述結果，本論文所提出之材料與閘極堆疊工程有效提升 GaN 基增強型元件的閘極控制能力、閾值電壓可調範圍及長期操作穩定性，為低功耗、高性能之 GaN 功率與射頻應用提供可行的技術途徑。

In this study, enhancement-mode ferroelectric HEMTs and enhancement-mode charge-trapping HEMTs were realized on the same GaN platform. Leveraging prior experience with high-aluminum charge-trapping dielectrics (Hf0.78Al0.22O), the gate stack was re-optimized with a lower-aluminum composition, Hf0.78Al0.22O. The revised dielectric suppresses gate leakage by two orders of magnitude, from 1.4 mA mm⁻¹ to 0.081 mA mm⁻¹, while expanding the tunable threshold-voltage window to > 6 V and ensuring stable normally-off operation.
Ferroelectric AlScN MIS-HEMTs were fabricated with 10-nm Al2O3/25-nm AlScN bilayer gates. Devices exhibit a peak transconductance of 88 mS mm⁻¹ and a maximum saturation current of 356.9 mA mm-1. A threshold-voltage shift (ΔVTH) of 12.47 V is obtained, with the forward-polarized state yielding VTH ≈ 0.8 V. Performance metrics remain comparable to conventional depletion-mode counterparts, indicating minimal compromise in on-state current or transconductance.
The combined results demonstrate a practical route to low-power, high-performance GaN transistors for power and RF applications, achieving enhanced gate control, extended VTH adjustability, and long-term stability under enhancement-mode bias.

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