氮化鋁鎵/氮化鎵高功率與射頻高電子遷移率電晶體之製作與分析

在此篇論文中，我們採用氮化鋁鎵/氮化鎵異質接面結構製作元件，利用氮化鎵優異的特性如寬能隙、高崩潰電壓、高電子遷移率與高頻率響應等來製作高功率與射頻元件並分析。本論文的第一部分為增強式元件的製作，利用感應藕合式電漿離子蝕刻機台移除閘極區域的氮化鋁鎵障壁層以空乏二維電子氣，並成長一層氧化鋁抑制閘極漏流，成功使臨界電壓從-5.27 V增加到0.47 V，獲得了增強式元件，並利用稀釋的氫氧化鉀做閘極掘入後的表面修復，藉由通道片電阻、遲滯曲線、電子遷移率與介面能態密度改善證實了此方法確實能提升閘極掘入後的元件特性。第二部份則是藉由氮化鎵可操作於高壓與高溫環境的特性，利用大面積的元件與多指結構達成高電流元件。在此章我們製作了連接式與跨接式閘極結構的元件，元件的最大電流達到7.1安培，並探討閘極寬度與指數對於元件特性的影響。最後是氮化鎵高頻元件的製作與分析，利用網路分析儀進行S參數的量測，利用ADS軟體建立元件的小訊號模型，模擬出元件參數後計算截止頻率與最大震盪頻率。

關鍵字

氮化鋁鎵/氮化鎵異質接面結構；高電子遷移率電晶體；閘極掘入；大面積元件；射頻元件；小訊號模型

並列摘要

In this thesis, we take advantage of the superior properties of GaN, such as wide bandgap, high breakdown voltage, high electron mobility and high frequency response to fabricate the high power and RF devices with AlGaN/GaN heterostructures. The first part is the fabrication and analysis of enhancement-mode devices. We use the ICP-RIE to remove the AlGaN barrier layer under the gate in order to deplete the 2DEG. Al2O3 is deposited to suppress the gate leakage. The threshold voltage has a positive shift from -5.27 V to 0.47 V which means that the e-mode device is successfully achieved. We also use the diluted KOH solution to recover the recessed surface after the recess etch. The improvement of channel sheet resistivity, hysteresis, mobility and density of states shows a convincing evidence that the KOH passivation is effective to recover the recessed region. In the third part, owing to the capability of high-temperature and high-voltage operation of GaN devices, we design the large-area and multi-finger devices to achieve high current. The devices are designed with inter-connected and connecting gate structure and the max current results in 7.4 A. Then we investigate the impact of the layout design including the gate width and the number of fingers. The last part is the fabrication and analysis of GaN RF device. We build the small-signal model by ADS and simulate each component in the circuit to calculate the cut-off frequency and maximum frequency of oscillation.

並列關鍵字

AlGaN/GaN heterostructure ； HEMTs ； gate recess ； large-area device ； RF device ； small-signal model

參考文獻

[1] U. K. Mishra, L. Shen, T. E. Kazior, et al., “GaN-Based RF power devices and ampliﬁers,” Proc. IEEE, vol. 96, no. 2, pp. 287–305, Feb. 2008.

[2] Alex Lidow, “Can Gallium Nitride Replace Silicon?” Power Electronics Europe, issue 2, 2010.

[4] IHS Technology, “Market Forecasts For Silicon Carbide & Gallium Nitride Power Semiconductors – 2016.”

[6] O. Ambacher, J. Smart, J. R. Shealy, N. G. Weimann, K. Chu, M. Murphy, W. J. Schaff, L. F. Eastman, R. Dimitrov, L. Wittmer, M. Stutzmann, W. Rieger and J. Hilsenbeck, ”Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures,” J. Appl. Phys., vol. 85, no. 6, pp.3222-3233, Mar. 1999.

[7] W. Huang, Z. Li, T. P. Chow, Y. Niiyama, T. Nomura, and S. Yoshida,“Enhancement-mode gan hybrid MOS-HEMTs with ron,sp of 20 mω –cm2,” in Proc. 20th Int. Symp. Power Semiconductor Devices ICs, May 2008, pp. 295–298.

國際替代計量

氮化鋁鎵/氮化鎵高功率與射頻高電子遷移率電晶體之製作與分析

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