本篇論文主要探討利用氧化製程改善氮化鋁鎵/氮化鎵蕭特基紫外光檢測器之特性，在眾多氧化製程中，我們選擇兩種非真空環境下即可完成且低成本之製作方法，分別為過氧化氫氧化法以及超音波噴霧熱烈解沉積法，並將氧化製程分別應用於三種紫外光檢測器上，分別為金屬-半導體-金屬(金-半-金)、蕭特基能障、金屬-絕緣體-半導體(金-絕-半)結構。
為了瞭解氧化層之薄膜厚度、化學組成、表面粗糙度、折射係數以及穿透度，在本研究中使用(一) 穿透式電子顯微鏡、(二) 化學分析電子儀、(三) 原子力顯微鏡、(四) 橢圓偏光儀與(五) 分光光譜儀。首先，運用穿透式電子顯微鏡加以確認此兩種氧化製程法所成長之氧化層厚度，再透過化學分析電子儀與定量分析確認所形成之氧化層為氧化鋁。此外，藉由原子力顯微鏡觀察氧化層之表面粗糙度，最後透過橢圓偏光儀與分光光譜儀之量測，分析氧化層之折射係數及其穿透度。
在瞭解氧化層之材料分析後，藉由將過氧化氫氧化技術應用於(一)金-半-金與(二)蕭特基能障結構紫外光檢測器上成長鈍化層，而我們發現經過鈍化處理之金-半-金結構紫外光檢測器相較於未經鈍化處理之元件可使暗電流降低10倍，同時發現光電流有提升的現象。此外，在紫外光對可見光之鑑別度上可以由20提升至2.11×10^3，在低頻雜訊量測部分，也發現雜訊電流有效的減少了，因而使得整個元件之雜訊等效功率下降，進而使得紫外光檢測器之感測度提升44倍。探討經鈍化處理之蕭特基結構紫外光檢測器，我們發現經鈍化處理之蕭特基能障結構紫外光檢測器相較於未經表面鈍化之元件，其暗電流約減少10^2倍，光電流也有所提升，在紫外光對可見光的鑑別度上可以由39改善至2.47×10^3，在感測度上更可以提升107倍。
此外，本論文研製以過氧化氫氧化技術以及超音波噴霧熱裂解沉積法成長氧化鋁作為絕緣層應用於金-絕-半結構之紫外光檢測器。首先，以不同過氧化氫氧化時間進行測試，使元件特性最佳化。經由實驗結果可以發現經過氧化氫處理5分鐘可以使元件具有最佳之特性。相較於蕭特基能障結構紫外光檢測器，以過氧化氫氧化法製作金-絕-半結構紫外光檢測器可抑制暗電流10^3倍，在紫外光對可見光之鑑別能力上可由39改善至7.46×10^4，在感測度上亦可提升10^2倍。再者，利用超音波噴霧熱裂解沉積法成長氧化鋁製作金-絕-半紫外光檢測器。實驗中發現利用超音波噴霧熱裂解沉積15nm的氧化鋁作為絕緣層之金-絕-半紫外光檢測器可以達到最佳的元件特性，相較於蕭特基能障紫外光檢測器，暗電流下降約10^3倍，紫外光對可見光之鑑別能力提升10^4倍，在感測度上更提升10^3倍。
為了要確認元件之熱穩定性，我們使用變溫量測加以觀察元件之特性，操作溫度分別為300K、360K、420K、480K，而經由量測結果可以發現金-半-金結構紫外光檢測器在420K，蕭特基能障與金-絕-半結構紫外光檢測器在480K的工作環境下仍可正常運作。
在本論文中，我們成功將兩種氧化技術應用於三種不同結構之紫外光檢測器上，根據量測結果討論及分析，此兩種氧化法皆可以有效改善紫外光檢測器之特性。此兩種氧化技術皆無須在真空環境下製作且所需成本較低，在實際工業應用上極具潛力。

The research mainly investigates on the improvement of AlGaN/GaN Schottky-based ultraviolet (UV) photodetectors (PDs) by using oxidation techniques. Among several oxidation methods, we choose two non-vacuum and low cost approaches to fabricate the oxide layer. One is the hydrogen peroxide (H2O2) oxidation technique, and the other one is ultrasonic spray pyrolysis deposition (USPD). Furthermore, these two oxidation techniques are applied to three different Schottky-based UV PDs including metal-semiconductor-metal (MSM), Schottky barrier (SB), and metal- insulator-semiconductor (MIS) structures.
In order to know oxide thickness, chemical composition, surface roughness, refractive index, and transmittance of the oxide layer, the (1) Transmission Electron Microscopy (TEM) (2) Electron Spectroscopy for Chemical Analysis (ESCA) (3) Atomic Force Microscopy (AFM), (4) Ellipsometry, and (5) UV/VIS/NIR spectrophotometer are adopted in this research. TEM is used to confirm the oxide thickness formed by two oxidation techniques. ESCA and the quantitative analysis are employed to confirm the Al2O3 oxide layer. Moreover, the surface roughness of the oxide layer is observed by AFM. The ellipsometry and UV/VIS/NIR spectrophotometer are operated to analyze the refractive index and the transmittance of the oxide layer.
After the material analysis of oxide layer, H2O2 oxidation technique was applied to (1) MSM and (2) SB UV PDs to form the passivation layer. Compared with MSM UV PD without H2O2 passivation, it was found that the dark current of MSM UV PD with H2O2 passivation was decreased by 10 times and the photocurrent was enhanced. Furthermore, the UV to visible rejection ratio (RUV/VIS) was increased from 20 to 2.11×103. In the low frequency noise measurement, the noise current was reduced so that the noise equivalent power was lowered. Moreover, the detectivity of UV PD was improved by 44 times. In addition, the performances of SB UV PD with H2O2 passivation were investigated. It was found that the dark current was reduced by 102 times and the photocurrent was increased compared to the SB UV PD without H2O2 passivation. Furthermore, the RUV/VIS was improved from 39 to 2.47×103. Moreover, the detectivity was enhanced by 107 times.
Additionally, the H2O2 oxidation technique and USPD were employed to form the Al2O3 as the insulator layer and then applied to MIS UV PDs. Firstly, we conducted experiments with different H2O2 treatment time to find the optimization of MIS UV PDs. According to the experimental results, it was found that using H2O2 treatment for 5 minutes could make the devices optimized. Compared with SB UV PD without H2O2 passivation, the dark current was suppressed by 103 times, and the RUV/VIS was increased from 39 to 7.46×104. Moreover, the detectivity was improved by 102 times. Furthermore, the oxide layer formed by USPD was employed to fabricate the MIS UV PDs. In the experiments, it was observed that the optimization of MIS UV PDs by USPD was obtained by depositing 15nm Al2O3. Compared with SB UV PD without H2O2 passivation, the dark current was decreased by 103 times. Moreover, the RUV/VIS was enhanced by 104 times and the detectivity was increased by 103 times.
For the purpose of investigating the thermal stability of UV PDs, the temperature-dependent measurement was used to observe the characteristics. The operating temperature was set at 300K, 360K, 420K, and 480K. Based on the experimental results, it was found that MSM UV PDs were capable of working at 420K. Furthermore, the SB and MIS UV PDs were able to be operated at 480K.
In this dissertation, we successfully applied two oxidation techniques to three different structures of Schottky-based UV PDs. According to the experimental results and analysis, these two oxidation techniques are both effective for improving the characteristics of UV PDs. These two oxidation techniques are non-vacuum and low cost fabrication methods which are potential in the industrial applications.

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