高頻氮化鋁鎵/氮化鎵與氮化鋁銦/氮化鎵高電子遷移率電晶體之製作與分析

The Fabrication and Analysis of High Frequency AlGaN/GaN HEMT and AlInN/GaN HEMT

劉政志(Cheng-Chih Liu)

指導教授 ： 黃智方

國立清華大學/電機資訊學院/電子工程研究所/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00686

摘要

本論文將就高阻值矽基板(111)上的氮化鋁鎵/氮化鎵高電子遷移率電晶體與氮化鋁銦/氮化鎵高電子遷移率電晶體的高頻與直流特性以及內部小訊號電路元件參數進行比較與分析。
在直流特性上以閘極線寬0.15μm，閘極至源極1μm的元件來看，氮化鋁銦/氮化鎵試片之元件其最大飽和電流與最大轉導增益分別為1271mA/mm與231mS/mm，而氮化鋁鎵/氮化鎵試片之最大飽和電流與最大轉導增益分別為900mA/mm與187mS/mm，顯見氮化鋁銦/氮化鎵較高的二維電子氣濃度對於飽和電流即直流轉導增益上當有幫助。然而這也使得氮化鋁銦/氮化鎵元件在漏電上卻較氮化鋁銦/氮化鎵來的大。
而在高頻特性的部分氮化鋁銦/氮化鎵試片之元件的ft與fmax分別為82GHz與70GHz，其值皆高於氮化鋁鎵/氮化鎵元件的75GHz與60GHz然而在功率特性方面則因為氮化鋁銦/氮化鎵元件漏電較嚴重而沒有氮化鋁鎵/氮化鎵理想。
最後我們透過小訊號電路模型的萃取，比較兩種試片在內部本質小訊號參數上的差異，透過本質參數的比較可以得知氮化鋁銦/氮化鎵元件在本質轉導上確實因其較高的載子濃度而擁有較高的電流與轉導增益以及高頻特性然而其漏電情況也較嚴重。

關鍵字

氮化鋁鎵/氮化鎵 ； 氮化鋁銦/氮化鎵 ； 小訊號電路模型

並列摘要

In this thesis, we compare the DC and RF characteristics of AlGaN/GaN and AlInN/GaN HEMTs and their equivalent small signal signal circuit model are constructed and compared.
For the DC characteristics the saturated current density(Idss) and the transconductance(Gm) of the AlInN/GaN HEMT is 1271mA/mm and 231mS/mm respectively which are higher than the AlGaN/GaN’s value 900mA/mm and 187mS/mm because of the higher 2DEG concentration in AlInN/GaN. But the leakage current of the AlInN/GaN HEMT is also higher than that of AlGaN/GaN HEMT.
For high frequency characteristics, the AlInN/GaN HEMT shows an ft=82GHz and an fmax=70GHz, which is also higher than the AlGaN/GaN’s numbers because of the higher transconductance of AlInN/GaN HEMT. But for RF power characteristics the AlInN/GaN HEMT is poor than AlGaN/GaN HEMT due to the higher leakage current of AlInN/GaN HEMT.
Finally we extract small signal parameters, contstruct equivalent circuit models, and compare their intrinsic values. From the extracted values, It is found that the intrinsic gm of AlInN/GaN HEMT is higher than the AlGaN/GaN which is also attributed to the higher carrier density on the AlInN/GaN wafer.

並列關鍵字

AlGaN/GaN ； AlInN/GaN ； small signal model

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