本研究採用不同面積、周長的Mesa，進一步量測其電流電壓特性，以觀察漏電流的趨勢，並證明對發光二極體來說，周長對漏電流的影響的確遠遠大於面積。除此之外，改變指叉型發光二極體中指叉的數量，觀察漏電流是否會隨著指叉的數量而倍增，可以輔佐驗證周長是否是影響漏電流的最大因素。另一方面，本研究改變指叉彼此間的間距，來探討物理蝕刻是否會造成不同程度的傷害，又會如何影響漏電流的趨勢，再分別利用二氧化矽(SiO2)、氮化矽(SiNx)、三氧化二鋁(Al2O3)作為鈍化層，並量測其電性，以此探討各個鈍化層對不同程度的損傷，其改善效果。
接著，以同樣的光罩圖形，製作出平面式不對稱電極寬度的金屬—半導體—金屬紫外光偵測器，就目前認知而言，平面式電極的金屬—半導體—金屬光偵測器會因為表面缺陷，捕捉電子電洞對而導致較高的暗電流，因此，藉由側壁鈍化之研究與理論相互呼應，看是否能再不阻擋光的照射，而有效地降低暗電流。除此之外，我們藉由改變手指電極的間距，觀察其光響應與時間響應的改變，以及長完鈍化層之後的元件特性之變化。

The thesis is divided into two parts. First, we investigate the fabrication and characterization of different mesa structure and observe the trend of leakage whether it is dominated by the perimeter or not for LEDs. Moreover, we change the finger number of interdigitated LEDs to proof that the leakage increases exponentially again. On the other hand, we would like to observe if ICP do different damages to different finger spacing of interdigitated LEDs and leads to different trend of leakage. In the end, we use different passivation such as Al2O3 by ALD, SiO2 and SiN by PECVD to improve the leakage.
Second, we attempt to apply the above research results on the metal- semiconductor-metal (MSM) photodetector by asymmetric electrode structures. As far as known, the surface leakage is the dominant mechanism for dark current for MSM PDs. With the higher density of trap states on the surface, the higher leakage current is obtained. Therefore, we would like to reduce the leakage current by depositing passivation layer, which is based on the previous research. Moreover, we also induce the theorem of Anti-reflection (AR) coating. We hope that the passivation can reduce the leakage current without blocking the light. On the other hand, we also change the finger spacing of MSM PDs to see what their difference in characteristics is.

摘要 I
Abstract II
誌謝 III
Contents IV
List of Figures VI
List of Tables X
Chapter 1 Introduction 1
1.1 Development of III-nitride-based optoelectric Device 1
1.2 Motivation and purpose 7
Chapter 2 The Basis of Theory 9
2.1 450-nm LED 9
2.1.1 Ohmic contacts on p-GaN 9
2.1.2 Transmission-line model (TLM) 11
2.1.3 Light-emitting diode (LED) 14
2.2 MSM UV photodetector 17
2.2.1 Schottky contact 18
2.2.2 Metal-semiconductor-metal photodetector 22
2.2.3 Responsivity and Quantum Efficiency 26
2.2.4 Noise equivalent Power (NEP) 27
2.2.5 Detectivity 30
2.2.6 Anti-reflection coating (AR coating) 30
Chapter 3 Device Structure and Fabrication 32
3.1 Epitaxial structure design concept 32
3.1.1 450-nm blue LED 32
3.1.2 MSM UV photodetector 34
3.2 Design and layout of photo mask 35
3.2.1 Transmission-line model (TLM) 35
3.2.2 Leakage analysis model 35
3.2.3 450-nm interdigitated LED 36
3.2.4 MSM UV PD 36
3.3 Fabrication process 40
3.3.1 Transmission-Line Model 40
3.3.2 450-nm interdigitated LED 43
3.3.3 MSM UV PD by asymmetric structure 48
Chapter 4 Results and Discussion 50
4.1 Transmission-Line Model (TLM) 50
4.2 Leakage analysis 51
4.3 450nm interdigitated mLED 53
4.4 MSM UV PD 62
4.4.1 Current-Voltage (I-V) Characteristics 62
4.4.2 Responsivity and Quantum Efficiency (Q.E.) 63
4.4.3 Noise Equivalent Power (NEP) and Detectivity 65
4.4.4 Time Response 67
Chapter 5 Conclusions 89
References 90

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