具波導模態共振反射鏡之共振腔增強型量子點紅外線偵測器

Abstract

本論文提出並透過模擬設計一個共振腔增強型量子點紅外線偵測器，其結構為一個Ge/SiO2次波長光柵當作上反射鏡，以及Al2O3/GaAs的分佈式布拉格反射鏡當做下反射鏡，夾住一個常規的n-i-n量子點紅外線偵測器當作共振腔，並設計成用來偵測8 μm的紅外線，而元件的整體厚度僅7.7 μm。根據我們的模擬，此共振腔增強型量子點紅外線偵測器的外部量子效率可高達58％至78％，與無共振腔的元件相較，其增強因子為7至20倍。我們亦透過模擬驗證我們設計的可行性。在實驗方面，由於在製程與量測上面臨到諸多問題，在經過一連串的改進後，所得到的元件特性不如預期，推測原因可能是樣品成長與製程的問題，論文最後針對此問題提出建議與評論。

In this thesis, we propose and simulate a device structure of resonant cavity-enhanced quantum-dot infrared photodetector (RCE-QDIP). The RCE-QDIP consists of a conventional n-i-n QDIP sandwiched by a bottom Al2O3/GaAs distributed Bragg reflector and a top mirror of Ge/SiO2 sub-wavelength grating. Aiming for detecting infrared at 8 μm, the total thickness of the device is only 7.7μm. Compared with a QDIP without cavity, the external quantum efficiencies of RCE-QDIP could be as high as 59%-78% with the enhancement factors of 7–30 in our simulation. The feasibility of our design is also verified by simulation. However, we still met many problems in our device processing and measurement. After a series of improvement, the characteristics of finished devices are not as expected. We speculate the reason is due to the problems in sample growth and fabrication. At last, this thesis presents suggestions and comments for this problem.