在本文中，首先在玻璃基板上蒸鍍鎳/金(3nm/6nm)金屬薄膜，以探討透明接觸電極的特性。利用光激發化學汽相沈積系統，在氧的環境中經過適當的回火，可改善鎳/金合金的穿透率，在波長520nm 之下，穿透率由65％增加至85％。我們在未參雜的氮化鎵上製作鎳/金蕭特基接觸，分別量測其電流-電壓特性曲線及蕭特基位障高度。可以發現，沈積在氮化鎵上的鎳金合金，在充滿氧的環境、600oＣ溫度下，回火3 分鐘，可得到最低的暗電流以及最高的蕭特基位障高度，高達9.4eV。
　　接下來，分別在未參雜的氮化鎵以及氮化鋁鎵/氮化鎵異質接面上，利用半透明的氧化鎳/金蕭特基位障接觸電極，製作金屬-半導體-金屬結構之光檢測器。這些光檢測器利用光激發化學汽相沈積系統在氧的環境下經過適當的回火後，我們可得到最佳的鎳/金合金穿透率、較高的蕭特基位障高度、及較大的光電流對暗電流比。在最大量子效率方面，利用光激發化學汽相沈積系統回火之未參雜的氮化鎵以及氮化鋁鎵/氮化鎵異質接面光檢測器分別為13% 以及57%。我們發現，利用氮化鋁鎵/氮化鎵異質接面結構，可得到較高的響應、較低的雜訊等級、以及較佳的檢測率。
　　我們利用AIXTRON 2600 G3HT 金屬有機化學汽相沈積系統，製作p-氮化銦鎵/氮化鎵（多重量子井）-n 雙功能元件。在反向偏壓的情況下，其展現出光檢測器的特性，同時，在順向偏下的情況下，擁有發光二極體的特性。我們也發現，元件大小愈大者，無論是光電流或暗電流，皆擁有較高電流密度。元件尺寸愈大者，其光電流、暗電流比隨著電壓的增加，下降的速度也愈快。
　　我們亦使用氮化銦鎵/氮化鎵多重量子井結構，利用光激發化學汽相沈積系統成長之二氧化矽層的成長與否，來製作金屬-絕緣層-半導體及金屬-半導體-金屬光檢測器。藉由在金屬電極與氮化銦鎵/氮化鎵多重量子井結構間，加入光激發化學汽相沈積系統成長之二氧化矽層，我們可成功的降低暗電流，同時保持合理之高的光電流。在53nm厚度二氧化矽層下，可得到高達1.53×103 光電流、暗電流比。

　　In this thesis, the property and characteristics of transparency contact, a thin Ni/Au (3nm/6nm) bi-layer metal film, deposited on the glass substrate was discussed. With proper annealed in oxygen by the photo-CVD systems, the transmittance of the Ni/Au alloyed layer can beimproved from 65％ to 85％ in the wavelength around 520nm. The Ni/Au un-doped GaN Schottky contact was manufactured and the I-V curve and Schottky barrier height were also measured. The Ni/Au deposited on un-doped GaN annealed in oxygen for 3min at 600℃ had the lower dark-current and the Schottky barrier height was up to 0.94 eV.
　　Then, u-GaN and AlGaN/GaN heterojunction MSM photodetectors with semi-transparent NiO/Au Schottky barrier contact electrodes were fabricated. By photo-CVD annealing these photodetectors in O2, it was found that we can achieve a larger Ni/Au transmittance, higher Schottky barrier heights and larger photocurrent to dark current contrast ratios. The maximum quantum efficiencies were 13% and 57% for the photo-CVD annealed u-GaN and AlGaN/GaN heterojunction photodetectors, respectively. Furthermore, we can achieve a larger responsivity, a lower noise level and a larger detectivity by using the AlGaN/GaN
heterojunction structure.
　　Moreover, the p-InGaN/GaN(MQW)-n double functions devices was fabricated by AIXTRON 2600 G3HT MOCVD system. It exhibited the photodetector properties in reverse bias and preserved the distinct identities of LED in forward bias at the same time. The bigger size of devices showed the higher current density in photo-current and dark
current. The contrast ratio of the big size device was more rapid than the small one.
　　InGaN/GaN MQW MIS and MSM photodetectors with and without photo-CVD SiO2 layers were fabricated successfully. It was indicated that we could significantly reduce the dark current, while still maintain a reasonably large photo current by inserting a photo-CVD SiO2 layer between metal electrodes and the underneath InGaN/GaN MQW structure. With a 53nm-thick SiO2 layer, it was also found that we could achieve a high 1.53×103 photo current to dark current contrast ratio.

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