在本論文中，我們用有機金屬氣相磊晶系統成長三五族氮化物及其相關化合物之光電元件，包含發光二極體和高電子移動率電晶體。我們首先利用改變低溫緩衝層的退火時間，在藍寶石基板上得到高品質的氮化鎵磊晶層，在低濃度的矽摻雜時(濃度為1.1x1017cm-3),電子移動率可達622cm2(V-s)-1。爾後，為了提升發光二極體的發光效率，在多重量子井成長之前插入以氮化銦鎵/氮化鎵的超晶格結構，利用該超晶格結構產生的二微電子氣體降低發光二極體的串聯電阻，並且使得電流散佈得到較佳的均勻性，提高二極體的亮度。同時，將藍寶石基板背面拋光後，鍍上鈦金屬得到鏡面的效果，將原來背面射出的光線反射回來，可提升發光亮度約一點五倍。
以有機金屬氣相磊晶系統成長的高移動率電晶體通常會有比較大的電晶體關閉特性，因此我們利用鎂(Mg)摻雜的電洞提供層來改善電晶體的關閉特性。但是因為電洞提供層跟未摻雜的氮化鎵磊晶層將形成一個PN接面,其所形成的內建電場會影響到電晶體通道中的電子移動率，因使我們成長不同厚度的通道層來研究該厚度對電晶體特性的影響。我們發現1800Å的厚度，電晶體有比較好的電子移動率及及本質增益。
為了改善電晶體的電壓電流特性，我們在電晶體的歐姆接觸部份,利用活性離子蝕刻的方式，將高能隙的氮化鋁鎵能障層部分薄化，不但改善了電晶體的歐姆特性，也發現源極-汲極電流因此提升約33％，而電晶體的本質增益也提高了26％。進一部的探討後，我們發現氮化鎵材料的高飽和電場是造成氮化鋁鎵/氮化鎵異質結構電晶體有較高轉折電壓的主要原因。

In this dissertation, the metal-organic chemical vapor deposition (MOCVD) was used for growth the III-V nitride based electronic and optical devices. High-quality GaN films are prepared by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). In situ optical reflectance traces reveal that the ramping time from low temperature to high temperature in the growth of the nucleation layer significantly affects the surface roughness. The mobility of the lightly doped GaN is as high as 622cm2/V-s at a corresponding carrier concentration of 1.1x1017cm-3. After the preparation of high quality n-GaN films, the LEDs with an InGaN/GaN superlattice layer are studied. The experimental results demonstrate that the current spreading layer can improve output power and turn on voltage (Vf) by forming a two dimensional electron gas (2DEG).
For reducing the pinch-off voltage of the AlGaN/GaN heterojunction field effect transistor, an Mg-doped insulating GaN layer is inserted to suppress the leakage current, improving the breakdown voltages and yielding excellent pinch-off characteristics. Finally, Al0.27Ga0.73N/GaN Ohmic-recessed heterostructure field-effect transistors (OR-HFETs) grown by low-pressure metal-organic chemical vapor deposition (LP-MOCVD) have been fabricated. Compared with the HFET without the ohmic-recessed process, the saturation current density, maximum extrinsic transconductance and RF characteristics of OR-HFET are significantly increased.

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