由於電子躍遷的選擇律之限制，量子井紅外線光偵測器僅能吸收電場分量垂直於量子井層的入射光。然而，可藉由非等向性蝕刻在量子井偵測器上製作V型谷結構，以耦合垂直入射之光線。入射光可藉由空氣及砷化鎵間介面的內部全反射或折射效應來耦合。
在本論文中，我們利用幾何光學來估計具V型谷結構之量子井偵測器耦合垂直入射光的效率。對於背面入光及上方入光的兩種情況，我們分別計算其耦合效率，而預測值和實驗值相當符合。
以對非等向性蝕刻的研究為基礎，我們提出一套程序，用來製作具V 型谷結構之量子井偵測器。此套程序成功的應用在我們的實驗中。對光電流響應的量測顯示，在背面入光及上方入光的兩種情況中，V型谷結構皆能有效耦合垂直入射光。
整體來說，實驗結果肯定了V型谷結構用來耦合垂直入射光的可行性。但是，由V型谷結構的週期性所引起的繞射效應還需進一步的研究，以強化耦合的效率。

Due to the selection rule of electron transition, quantum well infrared photodetectors (QWIPs) can only absorb light with the electric field component perpendicular to the QW layers. However, a V-groove structure can be fabricated on the QWIP by using anisotropic etching to couple the normal incident light. The incident light is coupled by the total internal reflection (TIR) or the refraction effect on the air-GaAs interface.
In this thesis, the efficiency for the QWIPs with V-groove structure to couple the normal incident light is estimated by applying the ray optics. For both the top-illuminated and back-illuminated condition, the coupling efficiencies are calculated respectively. The estimation coincides with the experiment results well.
Based on the study of anisotropic etching, a feasible processing procedure for fabricating a QWIP with V-grooves is proposed and successfully applied in our experiment. The responsivity measurement shows that the V-groove structure can effectively couple the normal incident light for either back-illuminated or top-illuminated case.
In summary, the experimental results confirm the applicability of the QWIPs with V-groove structure for coupling the normal incident light. But, the diffraction effect due to the periodic V-groove structure needs further study for enhancing the coupling efficiency.

Chapter 1 Introduction
Chapter 2 Design and Analysis of the QWIP with V-grooves
2.1 Method for Evaluating A Coupling Scheme
2.1.1 Analysis of the QWIP with Edge Coupling Scheme
2.1.2 Analysis of the QWIP with V-grooves
2.2 Coupling Efficiency of the QWIP with V-
grooves
2.3 The Interference Effect in the QWIP with V-
grooves
2.4 The Diffraction Effect of the QWIP with V-
grooves
Chapter 3 Fabrication Process of the QWIP With V-grooves
3.1 Anisotropic Etching of GaAs
3.2 Determining the substrate orientation and selecting the
etchant
3.3 The undercut problem
3.4 Processing Steps for Fabricating A QWIP with V-
grooves
Chapter 4 Experiment results and discussion
4.1 Device Structure of the QWIP
4.2 Absorption Measurement
4.3 Responsivity for Different Coupling
Schemes
4.4 The Current-Voltage
Characteristics
Chapter 5 Conclusions and Suggestion for Future Work
References

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