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標題: | T型閘極-高頻氮化鋁鎵/氮化鎵高電子遷移率電晶體之製作與分析 Fabrication and Analysis of High Frequency AlGaN/GaN HEMTs with T-shaped Gate |
作者: | Yung-Ting Ho 何咏庭 |
指導教授: | 吳肇欣(Chao-Hsin Wu) |
共同指導教授: | 黃定洧(Ding-Wei Huang) |
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,閘極絕入,障壁層厚度,高頻元件,小訊號模型,T型閘極, AlGaN/GaN heterostructure,HEMTs,gate recess,barrier thickness,RF device,Small-signal model,T-shaped gate, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 在本篇論文中,我們採用高阻值矽基板氮化鋁鎵/氮化鎵異質接面結構來製作元件,利用氮化鎵優異的特性如寬能隙、高崩潰電壓、高電子遷移率來製作HEMT高頻元件,接著利用T型閘極製程所具有的優異特性取代傳統Normal閘極製程,藉此提高元件在高頻特性的表現。
本論文的第一部分為T型閘極製程開發,我們利用Four-Layer Resist的放式進行製作,目的為降低閘極電阻值,使最大震盪頻率(fmax)與電流增益截止頻率(fT)能持續提升。 第二部分為元件的直流特性分析,我們成功利用電子束曝光顯影技術製作出T型閘極高電子遷移率電晶體,其閘極線寬最小為60-80奈米,使得元件之最高轉導值提升至367 mS/mm。為了解決元件在閘極線寬縮小後所面臨之短通道效應,我們降低氮化鋁鎵障壁層的厚度,使元件之開關比達到3-4個數量級,並針對不同障壁層厚度與元件尺寸進行探討。 最後為了分析元件的高頻特性,我們利用模擬軟件建立元件的小訊號模型,幫助我們分析元件內部小訊號參數的影響,同時也對不同偏壓點與元件尺寸進行探討,並模擬出元件的最大震盪頻率(fmax)與電流增益截止頻率(fT)。在閘極偏壓為-3.5 V與汲極偏壓為6 V的情況下,最佳元件之fT與fmax分別為51.2/97.7 GHz。 In this thesis, we take advantages of the superior properties of Gallium Nitride, such as wide bandgap, high breakdown voltage, high electron mobility to fabricate the RF devices with AlGaN/GaN heterostructures on 4-inch HR-substrate. We replace normal gate structure with T-shaped gate fabrication process due to some advantages of T-shaped gate structure, which improves the device performance at high frequency condition. The first part is the development of T-shaped Gate structure. In order to improve the maximum oscillation frequency (fmax) and current gain cutoff frequency (fT), we use Four-Layer Resist method to fabricate the T-Shaped Gate structure. The second part we analyze the DC characteristics of device. We successfully use E-beam lithography technology to fabricate T-Shaped Gate high electron mobility transistors, and the minimum gate length of the device is about 60-80 nm. The small gate length leads high transconductance(gm) about 367 mS/mm. The devices with gate length smaller than 100 nm will suffer from serve short channel effect., we use gate recessed technology to narrow the thickness of AlGaN barrier to avoid problem, and improve the On/off ratio about 3-4 orders of the devices. Finally, we discuss the DC characteristics of device with different AlGaN barrier thickness and geometric size. The last part is the analysis of RF characteristics, we build a Small-signal model and simulate each component in the circuit to help us understand the influence of each elements. We discuss the RF characteristics at different bias conditions and geometric size. At gate bias of -3.5 V and drain bias of 6 V, the fT and fmax of the golden device are 51.2/97.7 GHz, respectively. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/21441 |
DOI: | 10.6342/NTU201902514 |
全文授權: | 未授權 |
顯示於系所單位: | 光電工程學研究所 |
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ntu-108-1.pdf 目前未授權公開取用 | 6.04 MB | Adobe PDF |
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