臺灣博碩士論文加值系統

在本篇論文中，我們成功的利用金屬光柵讓正向入射光產生繞射，由於光柵有限尺寸的影響(入射光束大小遠大於光柵面積)TE極化光及TM極化光皆可被量子井紅外線偵測器吸收產生響應。在波長10.5μm的響應，我們發現對於不同入射方向光對響應頻譜的影響包括45度斜面入射、正面及背面之正向入射，光極化選擇性於背面入射時最為明顯。接下來，我們製作了兩種不同面積大小的光柵結構，而光線由正面入射，光極化選擇性正比於光柵的透光面積。在不同入射角度中，與法線夾角為30度時可以讓光極化選擇性最大。所以利用光柵結構我們製作出可以正向入射的紅外線偵測器，而且響應的波形可以利用光柵的繞射耦合來調變。由於光柵結構，光極化選擇性可以更為明顯。而在此元件中，亦可觀察到上述現象的實驗結果。

In this work, we have used metallic grating to diffract the normal incident radiation. Both TE-polarized and TM-polarized light can be detected by QWIP due to finite-size grating effect. For the response of 10.5 μm, we find polarization selectivity is more obvious under backside-illumination among the three different incident directions including normal incidence of 45o-facet, top and back side. And then, we fabricate two devices with the same grating period but different slit areas for topside-illumination. Polarization selectivity is proportional to the slit area. In the case of different incident light angle, polarization selectivity is the largest for the incident angle of 30o. In summary, the experimental results confirm the applicability of QWIPs with grating structure for normal incident light coupling and the tunable response shape. Polarization selectivity is also proposed to improve the photodetector performance. Finally, the above phenomenon is observable in our experimental results.

Abstract
摘要
Chapter 1：Introduction 1
References……………………………………………………..………………..3

Chapter 2：Infrared Photodetector　　　　　　　　　　　　　　　4
2.1 Background of Infrared Photodetector………………………..….……….4
2.1.1 Blackbody Radiation……………………………………………....4
2.1.2 Infrared Detector…………………………………………………..5
2.1.3 Intersubband Transition…………...………………………………6
2.1.5 Introduction of FTIR...……………………………………………7
2.2 GaAs / AlGaAs Multiple Quantum wells Infrared Photodetector…..…….7
2.3 Light Coupling……………..……………………………………………..9
2.4 Surface Plasmon………..…………………………………………………9
References……………………………………………..……..………………..16

Chapter 3：Fabrication Process and Measurement Setup of Device 17
3.1 Device Process…………..………………………………………………17
3.1.1 Sample Cleaning…………………………………………………17
3.1.2 Lithography……………………...………………………………18
3.1.3 Wet Etching……………………...…………………………........19
3.1.4 Metal Evaporation and Lift-off………………………………..19
3.1.5 Anneal……………………………………………………………20
3.1.6 Polish Facet and Wire Bonding.……………………………….20
3.2 Instrument Setup and Characteristics Measurement……………….......21
3.2.1 Spectral Response………………………………………………..21
3.2.2 Responsivity…………………………………………………...22
3.2.3 Dark Current and Photocurrent Measurement…………………23
3.2.4 Noise Equivalent Power and Detectivity………………………...24
References……………………………………………………………………30

Chapter 4：Experiment Result and Discussion 31
4.1 Detector Structure………………………………………………….…...31
4.1.1 Sample Structure………………………………………………...31
4.1.2 Surface Structure………………………………………………...32
4.2 Design Principle………………………………………………………..32
4.3 Experimental Results of Detector Characteristics….…………………..33
4.3.1 Current-Voltage Characteristics………...………………………33
4.3.2 Sample with 45-degree Facet Coupling ….…………………….35
4.3.3 Samples with Normal Incidence from Top Side.…….………….35
4.3.4 Samples with Normal Incidence from Back Side.……………….37
4.4 Discussion……………………………………………………………...37
4.4.1 Three Different Light Incident Directions.….…………………..38
4.4.2 Polarization………...……………………………………………38
4.4.3 Photoresponse with Different Open Fractions of Grating……..39
4.4.4 Photoresponse with Different Incident Angle…….……………40
References……………………………………………………………………68

Chapter 5：Conclusion and Suggestion for Future Work 69

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