使用ALD在一般HEMT結構上沉積氧化鋁Al2O3當成閘汲絕緣層形成MOSHEMT S.S.GaO
Outline Introduction Experiment Results and discussion Conclusion References
Introduction One of the major factors that limit the performance and reliability of GaN high-electron-mobility-transistors (HEMTs) for high-power radio-frequency (rf) applications is their relatively high gate leakage. The gate leakage reduces the breakdown voltage and the power-added efficiency while increasing the noise figure. 限制HEMTs性能和高功率射頻rf應用可靠性的主要因素，是其相對較高的柵極洩漏。 柵極洩漏降低擊穿電壓和功率附加效率，同時增加雜訊係數。
Introduction Atomic layer deposition (ALD) is a surface controlled layer-by-layer process for the deposition of thin films with atomic layer accuracy. The thickness control of the ALD films thus scalability is much superior than those of the plasma-enhanced-chemicalvapor-deposition (PECVD) grown SiO2 and Si3N4. ALD是可控的表面層 - 層工藝，可精準控制沉積薄膜原子層。 ALD的薄膜的厚度控制從而擴展性優異得多高於等離子體增強化學-蒸汽 - 的沉積PECVD生長的SiO2和Si3N4。
Experiment Current collapse
Results and discussion
Results and discussion 傳輸特性，轉導特性 gm越大，亦即同樣的輸入小信號電壓可以產生較多的小信號電流在輸出端， 而較大的輸出端小信號電流再乘上輸出端等效電阻，便可得到較大的輸出端電壓 因此電壓增益提升。 另外，一個元件的gm值較大，則此元件也可以達到較高的操作速度(電流單增益頻率高)。 你可以想成是因為小信號電流比較大，在高頻率時充放電電容較容易。
Conclusion ALD Al2O3 was proven to be an excellent gate dielectric for GaN MOS-HEMTs. The present MOS-HEMT exhibits favorable characteristics when compared to GaN HEMTs. The present MOS-HEMT shows low leakage current, high breakdown voltage, strong accumulation, and high effective 2D electron mobility under both low and high transverse fields. These characteristics imply excellent potential of the ALD Al2O3/AlGaN/GaN MOS-HEMT for highpower rf applications. ALD AL2O3證明了為優良電介質，表現出良好的特性，顯示低漏電流，高擊穿電壓，高載子傳輸，意味著有出色的潛力在高頻應用
References P. D. Ye, B. Yang, K. K. Ng, J. Bude, G. D. Wilk, S. Halder, and J. C. M. Hwang“GaN metal-oxide-semiconductor high-electron-mobility-transistor with atomic layer deposited Al2O3 as gate dielectric”
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