臺灣博碩士論文加值系統

我們已經製作並且描繪出一個工作波段在1.55微米的矽基板光波導調變器，它的結構包含了接面場效電晶體和PIN二極體，並且結合了脊狀波導，而元件的基板是重摻雜矽基板，並且在這之上磊晶一層輕摻雜的矽磊晶層。除此之外，光調變機制是經由自由載子散射效應來達成，最重要的是，這個元件成功地將光和電子元件整合在一起。 為了定義出p型和n型的區域，我們採用了SOD熱擴散法。從實驗的結果顯示，此元件呈現電晶體的特性，並且從電荷耦合器的影像中，我們可以觀察到光訊號會被通道中的自由載子所吸收。在適當的偏壓之下 ，此元件之動態調變深度和靜態調變深度均可達到100%。除此之外，在調變深度高達95%以上的情況下，元件的調變頻率可以高達5k赫茲。

We have fabricated and characterized a Si-based optical waveguide modulator working at the wavelength of 1.55 μm. It consists of a joint version of JFET and p-i-n diode structures integrated with a silicon rib waveguide on epitaxial Si wafers. Besides, the optical modulation mechanism was achieved via free carrier dispersion effect. Above all, the waveguide modulator successfully integrates the functions of optical and electronic devices altogether in a silicon substrate. The spin-on-dopant (SOD) method was utilized to define the p- and n-doped regions. The results of our experiments revealed that the devices present transistor characteristics. According to CCD images, we can observe that the light is absorbed by the plasma sitting within the optical channel. The device exhibits both the static and dynamic modulation depth of ~100% at the chosen driving conditions. In addition, a modulation depth above 95% was observed for modulation frequency up to 5 kHz.

Abstract (In Chinese) I
Abstract (In English) II
ACKNOWLEDGEMENTS III
Contents IV
Table Captions VI
Figure Captions VII

Chapter 1 Introduction 1
1-1 The background of silicon photonics 1
1-2 Organization of the thesis 5

Chapter 2 Fundamental theory 6
2-1 Snell’s law and total internal reflection (TIR) 6
2-2 The Goos-Hanchen shift 8
2-3 Optical modulation mechanisms in silicon 9
2-3-1 Electric field effects 9
2-3-2 Free carrier dispersion effect 12
2-3-3 Thermo-optical effect 14
2-4 Basic pn JFET operation 15

Chapter 3 Experiment I – Optical modulator without trenches 19
3-1 Device structure 19
3-2 Fabrication process 22
3-3 SOD process . 26

Chapter 4 Results and Discussion I 27
4-1 Spreading resistance probe measurements 27
4-2 Electrical measurements 28
4-2-1 Two terminals I-V curves (Gate-Source) 28
4-2-2 The I-V characteristics of three-terminal transistors 32
4-3 Optical measurements 36
4-3-1 Modulation depth measurements 37
4-3-2 CCD image measurements 43
4-4 Response speed measurements 55
4-5 Summaries 64

Chapter 5 Experiment II - Optical modulator with trenches 65
5-1 Device structure 65
5-2 Fabrication process 66

Chapter 6 Results and Discussion II 67
6-1 Electrical measurements 67
6-2 Optical measurements 71
6-2-1 Modulation depth measurements 71
6-2-2 CCD image measurements 75
6-3 Response speed measurements 86
6-4 Summaries 90

Chapter 7 Conclusions and Future work 91
7-1 Conclusions 91
7-2 Future work 92

References 93

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