在本論文中，我們研究高效能氮化鋁銦鎵/氮化鎵金氧半增強式雙場板結構高電子遷移率電晶體。
首先，我們採用了四元化合物基板氮化鋁銦鎵的設計，其優點為在三元化合物銦鋁中加入鎵元素來減少銦元素使用的比例，此舉可以減少銦坑洞造成的磊晶缺陷也能更好調整四元化合物能隙及晶格常數，可以保有與氮化鋁銦/氮化鎵元件差不多電性表現的同時有更好的承受電壓的效果，更適合做為高功率元件。
達成增強式的元件我們使用氟離子摻雜的方式，因為氟離子擁有所有元素中最大的電負度，可以有效空乏通道中的二維電子氣。接著我們使用氮化矽當作鈍化層，可以減少表面缺陷，有效抑制在電晶體表面的電流崩潰。且閘極下方的氮化矽鈍化層形成場板，達到分散電場的作用。在閘極介電層的部分則是採用氧化鋁結構。
我們使用了雙場板的結構，分別為閘極場板和汲極場板，藉由場板來分散電場，使崩潰電壓提升。而對於閘極場板和汲極場板各自所擁有的改善崩潰效果，我們分別製作只有閘極場板，以及只有汲極場板的元件來分別比較。
除了基本的電性分析之外，我們也對元件進行材料分析。例如使用X射線光電子能譜(XPS) 、X射線繞射(XRD)分析氧化鋁和氮化矽的化學元素組成；原子力顯微鏡(AFM)和穿透式電子顯微鏡(TEM)觀測元件厚度和粗糙度。
在電性分析上首先我們製作沒有場板的氮化鋁銦鎵/氮化鎵金氧半高電子遷移率電晶體，藉由氟離子的調變，其元件的電性為閾值電壓為1.6V，開關電流比為5.65×109，次臨界擺幅為80 mV/decade，最大汲極電流為760 mA / mm，崩潰電壓為635 V。
接著為了分散閘極下方電場，我們製作只有閘極場板的元件來確認其場板的功效，該元件的臨界電壓為1.6 V，開關電流比為1.6×109，次臨界擺幅為79 mV/decade，最大汲極電流為727 mA / mm，崩潰電壓為835 V。接著我們製作只有汲極場板的元件，得到該元件的臨界電壓為1.56 V，開關電流比為9.1×109，次臨界擺幅為83mV/decade，最大汲極電流為725 mA / mm，崩潰電壓為725 V。相較於沒有場板的元件，我們製作的閘極場板和汲極場板皆有助於崩潰的提升。
因此我們製作同時擁有閘極場板以及汲極場板的元件，雙場板元件的臨界電壓為1.6 V，開關電流比為2×109，次臨界擺幅為86 mV/decade，最大汲極電流為732 mA / mm，崩潰電壓為945 V，BFOM為490 MW/cm2，證明其作為高功率元件具有非常大的潛能。

In this work, we demonstrated a high performance Enhancement-mode InAlGaN/GaN MOSHEMT with gate and drain field plate structures.
First, we use a quaternary compound InAlGaN as our barrier layer. The rationale behind this choice is that while the InAlN/GaN heterostructure exhibits a strong two-dimensional electron gas and excellent electrical performance, it is plagued by challenges in epitaxial growth and the formation of indium pits. By reducing the indium composition and adding Gallium into InAlN, we can not only reduce the epitaxial defects due to indium pits but moderate the lattice constant and bandgap energy. Therefore, the InAlGaN/GaN heterostructure can possess almost the same great DC performance as InAlN/GaN heterostructure and get lager breakdown voltage than InAlN/GaN heterostructure, which is more suitable for high power applications.
To achieve enhancement mode, fluoride ion doping is employed due to the high electronegativity of fluoride ions, which surpasses that of all other elements. It can deplete the two-dimensional electron gas in the channel effectively. Then we use silicon nitride as a passivation layer, which can reduce surface defects and suppress the current collapse on the surface. Moreover, the silicon nitride passivation layer under the gate forms a field plate to disperse the electric field. For the gate dielectric layer, the aluminum oxide structure is used.
In order to disperse the electric field and increase the breakdown voltage, the gate and drain field plates are used. To evaluate the improvement in breakdown voltage achieved by the gate field plate and drain field plate, two separate devices are fabricated: one with solely a gate field plate and another with solely a drain field plate. These devices are then compared to analyze the influence of each field plate on the improvement of breakdown voltage.
We perform some material analyses on our devices, such as using x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to analyze the chemical element composition of the dielectric layer and passivation layer, and using atomic force microscope (AFM) and transmission electron microscopy (TEM) to figure out the surface roughness and structure thickness.
For the DC characteristic, we first fabricated a E-mode InAlGaN/GaN MOSHEMT without field plates. The device has a threshold voltage of 1.6V, an on/off current ratio of 5.65×109, a sub-threshold swing (S.S.) of 80 mV/decade, an on-state current (Ion) of 760 mA/mm, and the breakdown voltage (VBR) is 635 V. Then we fabricated a device with only a gate field plate. The device has a threshold voltage of 1.6V, an on/off current ratio of 1.6×109, a sub-threshold swing (S.S.) of 79 mV/decade, an on-state current (Ion) of 727 mA/mm, and the breakdown voltage (VBR) is 835 V. Next we fabricated a device with only a drain field plate. The device has a threshold voltage of 1.56V, an on/off current ratio of 9.1×109, a sub-threshold swing (S.S.) of 83 mV/decade, an on-state current (Ion) of 725 mA/mm, and the breakdown voltage (VBR) is 725 V. Compared with the device without field plates, the gate field plate and the drain field plate are both efficient in improving the breakdown.
Finally, we fabricate a E-mode InAlGaN/GaN MOSHEMT with both gate and drain field plates. The device has a threshold voltage of 1.6V, an on/off current ratio of 2×109, a sub-threshold swing (S.S.) of 86 mV/decade, an on-state current (Ion) of 732 mA/mm, the breakdown voltage (VBR) is 945 V and the BFOM is 490MW/cm2. The performance of InAlGaN/GaN device has exhibited substantial enhancements, indicating the promising prospects as high-power devices in the future.

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