HEMT的開發始於1980年，成功後立即開始在AlGaAs / GaAs異質結構上的實驗，揭示了形成具有增強的電子遷移率的二維電子氣（2DEG）。早期的HEMT利用了由AlGaAs阻擋層和GaAs溝道結構組成，這是最廣泛研究的系統當時最了解的異質結系統。但在低溫下，HEMT的元件特性會下降許多，這是由於n-AlGaAs存在一層所謂的Deep donor levels (DX centers)，他能釋放或獲得電子，使2-DEG濃度隨著溫度改變，導致Vth不穩定，隨著Al含量的增加，AlGaAs / GaAs之間的帶隙不連續性增加，帶隙不連續性增加呢，能使通道中電子的更好限制。然而，存在深複雜中心（DX中心）現象，而Al含量超過20％，這會捕獲電子並影響器件性能。在20世紀80年代中期，為了想要改善元件缺點， AlGaAs / InGaAs假晶HEMTs和高銦的組成。與GaAs相比，InGaAs是優於GaAs的溝道材料，因為它擁有比較優異的傳輸能力。但是，AlGaAs / InGaAs pHEMT，In含量限制在25％以保存高層質量。因此，導帶不連續性受到限制。此外，InP基底更昂貴，更脆弱，並且更難以蝕刻，這使其難以競爭以6英寸晶圓製造的GaAs晶體管的每芯片成本。因此呢，想要尋找一種能夠製造高性能晶體管的方法在較不易碎和較大直徑的GaAs襯底上的內含物通道。這就是製造變質GaAs HEMT（GaAs mHEMT）的概念。因此，需要降低柵長設備來改善器件增益，噪聲和功率性能。為了要比較小線寬InAlAs / InGaAs mHEMT的器件性能，柵極長度範圍為0.5μm至3μm的器件，採用ebeam來製作。將介紹這些設備的直流特性，射頻特性以及雜訊的探討。具有Al2O3作為柵極氧化物的0.5μm InAlAs/ InGaAs MISHEMT具有454mA / mm的漏極飽和電流密度和138mS / mm的最大跨導。 fT和fMAX分別為23.56和30.05 GHz。 當VDS為2 V時，噪聲係數小於6 dB。

The development of HEMT began in 1980.After the success, experiments on AlGaAs/GaAs heterostructures began immediately, revealing the formation of two-dimensional electron gas 2DEG with enhanced electron mobility. Early HEMTs utilized an AlGaAs barrier layer and a GaAs channel structure, which is the most widely known heterojunction system at the time. However, at low temperatures, the HEMT's component characteristics are much lower. This is due to the presence of a so-called Deep donor levels (DX centers) in n-AlGaAs, which can release or acquire electrons, causing the 2-DEG concentration to change with temperature, resulting in Vth. Unstable, as the Al content increases, the band gap discontinuity between AlGaAs / GaAs increases, and the band gap discontinuity increases, which can better limit the electrons in the channel. However, there is a deep complex center (DX center) phenomenon, and the Al content exceeds 20%, which captures electrons and affects device performance. In the 1978s, in order to further improve device characteristics, AlGaAs / InGaAs pHEMTs and high indium compositions. Compared to GaAs, InGaAs is a channel material superior to GaAs because of its excellent transmission properties. However, AlGaAs / InGaAs pHEMT, In content is limited to 25% to preserve high-level quality. Therefore, the conduction band discontinuity is limited. In addition, InP substrates are more fragile, more expensive, and more difficult to etch and obtain, making it difficult to compete for the cost per chip of GaAs transistors fabricated on 6-inch wafers. Therefore, we hope to find a way to fabricate high performance, high performance transistors on the less fragile and larger diameter GaAs substrate. This is the concept of manufacturing a metamorphic GaAs HEMT (GaAs mHEMT). Therefore, there is a need to reduce gate length devices to improve device DC characteristics, noise figure, and RF performance. To characterize and compare the device performance of submicron InAlAs / InGaAs mHEMTs, devices with gate lengths ranging from 0.5μm to 3μm were fabricated using ebeam. The DC characteristics, RF performance and noise figure analysis of these devices will be introduced. The 0.5μm InAlAs/ In‎GaAs MISHEMT with Al2O3 as gate oxide has a drain saturation current density of 454 mA/mm and maximum transconductance of 138 mS/mm. The fT and fMAX were 23.56 and 30.05 GHz, respectively. When VDS at 2 V, the noise figure was less than 6 dB.

Content
中文摘要............2
Abstract...........4
致謝................6
Content.............8
List of Figures......10
List of Tables...........12
Chapter 1 Introduction........13
1.1 Overview of GaAs and InP-based HEMT……………………………………..13
1.2 Introduction of the InAlAs/InGaAs metamorphic HEMTs(mHEMT) ………..17
1.3 Low noise amplify Application………………………………………………..19
1.4 Objectives and Scope of the Present Research………………………………...21
Chapter 2 Fundamental Principles of High Frequency Measurement 22
2-1 Small-signal performance……………………………………………………..22
2.2 Noise figure performance ……………………………………………………..27
Chapter 3 Design and Fabrication of In‎AlAs/In‎GaAs mHEMTs 29
3-1 Design of Experiment…………………..……………………………………..29
3-2 Device layout design…………………………………………………………..30
3-3 Process flow of RF-MISHEMT……………………………………………….31

Chapter 4 Result and Discussion..............................42
4-1 InAlAs/InGaAs MS-HEMT with Different Gate length……………..………..43
4-2 InAlAs/InGaAs MIS-HEMT with Different Gate length……………………..49
Chapter 5 Conclusions and Future work.....................58
5-1 Conclusions………………………………………………………..…………..58
5-2 Future work……………………………………………………………..……..60
Reference..................................60

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