氮化鎵系列半導體材料，相當適合應用於光電元件以及高頻、高功率的電子元件之製作。直接能隙之氮化鎵系列的半導體材料具有低雜訊、高電子飽和速度、高崩潰電壓以及高工作溫度等優點。基於上述優點，就已蕭特基接觸閘極之元件而言，已有金半場效電晶體、異質接面場效電晶體以及高電子移動率電晶體等元件的研究。我們利用載子在二維電子氣通道中的高移動率以及大電場操作下的熱電子效應及穿隧效應，使載子脫離二維電子氣通道，進入較低移動率的通道層，藉此產生負微分電阻現象。負微分電阻效應更是目前最有力的微波產生機制。傳統的金氧半場效電晶體以及金半場效電晶體可用於組成邏輯電路，但這需要多個元件架構才能執行單一邏輯程式，而單一位置空間轉移電晶體即可執行邏輯電路中的數學功能，在積體電路製作上，可以達到整合及微縮的應用目的。在本研究中，希望製作高頻、高波峰波谷電流比之負微分電阻特性之位置空間轉移電晶體，以提升積體電路微縮之能力與競爭力。

GaN-based semiconductors are promising candidates, not only for optoelectronic devices, but also for high-frequency and high-power electronic devices. Advantages of these direct energy bandgap GaN-based semiconductors include low generation noises, high electron saturation velocity, high breakdown voltage, and high operation temperature. In view of the these advantages, GaN-based semiconductors have been successfully used in electronic devices and optoelectronic devices. Using Schottky gate, the performances of metal-semiconductor field effect transistors (MESFETs), heterojunction field effect transistors (HFETs), and high electron mobility transistors (HEMTs) have been demonstrated. We used the properties of high electron mobility in two dimensional electron gases channel, hot carrier effect and tunneling effect at high electrical field to induce the transport of electrons from high mobility channel to adjacent channel with low carrier mobility. Owing to this phenomenon, negative differential resistance (NDR) will appear and it is a powerful microwave mechanism up to now. Conventional metal-oxide-semiconductor field effect transistors (MOSFETs) and metal-semiconductor field effect transistors (MESFETs) can be used to fabricate logic circuits, but one logic function needs several MOSFETs or MESFETs. A real-space transfer transistors (RSTTs) could operate several logic functions and can be used in integrated circuits to reduce the number of devices and circuit area. In this study, real-space transfer transistors (RSTTs) with high cut-off frequency and obvious negative differential resistance phenomenon would be fabricated to promote the scaling and competitive ability in the integrated circuits.

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