本論文主要提出利用表面氯化處理對氮化鎵/氮化鋁鎵金屬-半導體-金屬光檢測器之光電特性和低頻雜訊進行改善，並利用光電化學氧化法在指叉狀電極間成長氧化鎵作為護佈，更進一步改善元件之特性。由於一般由有機金屬化學氣相沉積法成長的氮化鎵系列半導體在表面存在表面態位和鎵懸鍵，這些缺陷的存在降低了氮化鎵元件的工作表現。表面氯化處理有效改善由表面態位缺陷產生的內部增益，在偏壓5V與入射光波長360nm時，元件的量子效率×內部增益分別從無氯化處理的188.0%降低至氯化處理後的44.2%，元件的紫外-可見光拒斥比也從無氯化處理的7.32×101提升至氯化處理後的6.67×102；另一方面，表面氧化層護佈能更加減少表面態位，並使得元件表面的反射率有所下降，進而提升元件的量子效率，元件的量子效率×內部增益提升至47.6%、紫外-可見光拒斥比也提升至8.20×102。
　　表面氯化處理使得氮化鎵表面態位減少，同時也改善金屬-半導體蕭特基接觸，進而改善低頻雜訊；利用光電化學氧化法在指叉狀電極間成長氧化鎵作為護佈也會改善元件在低頻雜訊的表現，氧化層護佈使得氮化鎵表面態位減少，更進一步改善低頻雜訊。在偏壓5V時，無處理元件、表面氯化處理元件及表面氯化處理與氧化層護佈元件的等效雜訊功率分別為6.68×10–12 W、1.60×10–12 W和1.28×10–12 W，檢測度分別為4.7×1010 cmHz0.5W–1、1.9×1011 cmHz0.5W–1和2.5×1011 cmHz0.5W–1。

To improve the optoelectronic characteristics and low frequency noise of GaN/AlGaN metal-semiconductor-metal photodetectors (MSM-PDs), the chlorination surface treatment is applied in fabrication. Furthermore, a photoelectrochemical oxidation method is used to directly grow the oxide film of GaN between the interdigital electrodes of GaN/AlGaN MSM-PDs. This acts as a passivation layer to improve the characteristics of GaN/AlGaN MSM-PDs. The interface between metal and semiconductors is important for GaN-based devices due to the existence of surface states and Ga dangling bonds growth using metalorganic chemical vapor deposition (MOCVD). The surface states and Ga dangling bonds degrade the performance of GaN-based devices. The internal gain which attributed to the surface states can be suppressed by the chlorination surface treatment. The products of quantum efficiency and internal gain of the GaN/AlGaN MSM-PDs with and without chlorination surface treatment under a voltage of 5 V at a wavelength of 360 nm is 180.0% and 44.2%, respectively. The UV-visible rejection ratio of 6.67×102 and 7.32×101 was obtained for the GaN/AlGaN MSN-PDs with and without chlorination surface treatment. Besides, the process of oxide passivation grow by PEC can even more reduce the surface states and decrease the reflectivity on the surface of GaN. The products of quantum efficiency and internal gain of the GaN/AlGaN MSM-PDs with oxide passivation can be increase to 47.6%. The UV-visible rejection ratio of 8.20×102 was obtained.

　　The chlorination surface treatment effectively brings about a reduction on the surface state density of GaN samples. The Schottky contact of the chlorine-treated GaN/AlGaN MSM-PDs is also improved, so that the level of low frequency noise can efficiently be reduced. Furthermore, the process of oxide passivation can even more suppress the level of low frequency noise of GaN/AlGaN MSM-PDs. The noise equivalent power for the untreated, chlorine-treated, and oxide-passivated MSM-PDs, operated at 5 V, was 6.68×10–12 W, 1.60×10–12 W, and 1.28×10–12 W, respectively. The normalized detectivity for the untreated, chlorine-treated, and oxide-passivated MSM-PDs, operated at 5 V, was 4.7×1010 cmHz0.5W–1, 1.9×1011 cmHz0.5W–1, and 2.5×1011 cmHz0.5W–1, respectively.

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