P-型GaN閘極高電子遷移率電晶體之磊晶層設計與成長;Design and Growth of p-GaN Gate AlGaN/GaN High Electron Mobility Transistors

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題名:	P-型GaN閘極高電子遷移率電晶體之磊晶層設計與成長;Design and Growth of p-GaN Gate AlGaN/GaN High Electron Mobility Transistors
作者:	郗靖加;JIA, CHIH JING
貢獻者:	光電科學與工程學系
關鍵詞:	有機金屬化學蒸汽沉積系統;氮化鎵;MOCVD;GaN;p-GaN;HEMT
日期:	2021-11-04
上傳時間:	2021-12-07 12:03:56 (UTC+8)
出版者:	國立中央大學
摘要:	現今商用增強型(E-mode)高功率氮化鎵異質場效電晶體中，p 型氮化鎵 (p-GaN)閘極是常用的閘極結構之一，此閘極對元件開關時的動態特性影響以及與可靠度的關聯性是必須要了解的重要研究課題。本論文主要提出利用 P-型 GaN 閘極的方式來製作出增強型(Enhancement-mode)操作之氮化鋁鎵/氮化鎵場效功率電晶體，以用於電源供應器內的功率電晶體，將目標設在實現具有高閾值電壓、高導通電流、低導通電阻、低閘極漏電流的元件，以上述四主要特性做延伸，著重在磊晶結構的設計與磊晶條件參數的探討。此研究係利用有機金屬化學蒸汽沉積系統(Metal-Organic Chemical Vapor Deposition, MOCVD)沉積 GaN 磊晶層在矽基板上，使用不同鋁含量的 AlGaN 位障層，與不同濃度的鎂摻雜 p-GaN 閘極，探討背後物理意義並且組合出四種不同結構。為了更了解不同 p-GaN 長晶條件的影響，也設計了高溫和低溫，濃度高與濃度低四種 P-型 GaN 閘極的長晶條件，研究其變化對元件電性帶來的影響。此研究顯示，用計算能帶的方式可以看出元件的閾值電壓走向，有助於設計磊晶結構。在磊晶的層面，p-GaN的磊晶條件中，溫度990°C比起1020°C有更低的表面粗糙度，且可以降低 Mg 的擴散深度。在這四種結構中，以鋁成分 18%的 AlGaN 位障層搭配濃度 8E18 ???3鎂摻雜的 p-GaN 磊晶層的結構可得最高之閾值電壓，低鋁含量的位障層使極化效應降低，但不影響遷移率的表現，讓 HEMT 的閘極更容易達到常關型狀態。搭配上低濃度的 Mg 摻雜 p-GaN，使表面更加平坦，也讓 Mg 的向外擴散較低，使電子遷移率不被其影響，這是本研究根據元件結果推理出來的最佳結構。 ;In recent years, commercial enhancement-mode (E-mode) high-power gallium nitride heterogeneous field-effect transistors with the p-type gallium nitride (p-GaN) gate have become the most commonly used gate structures. The influence of dynamic characteristics and the correlation with reliability are important research topics that must be understood. The mainly propose of this work is the use of P-type GaN gates to achieve enhancement-mode operation AlGaN/GaN field-effect power transistors, which are used for transistors in power supply components. The objective of the design is high threshold voltage, high on-current, low on-resistance, and low gate leakage current. The above stated four conditions are extended, focusing on the design of the epitaxial structure and the conditional parameters of the epitaxial process. The AlGaN/GaN HEMT epilayers were grown on a Si substrate using Metal-Organic Chemical Vapor Deposition (MOCVD). We design four types of AlGaN barrier layers with different aluminum content, and different concentrations of magnesium doped p-GaN gates, four types of P-type GaN gate growth processes at high temperature and low temperature, high concentration and low concentration are designed to study the impact of their changes on the electrical properties of the device in order to better understand the performance of different p-GaN growth conditions. The results show that the threshold voltage trend of the device can be seen by calculating the energy band, which is helpful for the design of the device structure. The temperature of 990°C has better surface roughness than 1020°C at the epitaxial level in the epitaxial conditions of p-GaN, and can reduce the distance of Mg diffusion. The AlGaN barrier layer, with an Al content of 18% and a Mg-doped p-GaN epitaxial layer concentration of 8×?10?^18 ?cm?^(-3), is the best of these four structures. The low-Al barrier layer minimizes polarization while having little influence on electron mobility, making the gate easier to reach normally off condition. Since the surface of Mg-doped p-GaN is smoother and Mg out-diffusion is reduced at low concentrations, electron mobility is not deteriorated. This structure has shown excellent device results in this research work.
顯示於類別:	[光電科學研究所] 博碩士論文

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