單石波導耦合式砷化銦量子點微碟光偵測器

Abstract

本文的研究主題為單石波導耦合式砷化銦量子點微碟光偵測器。 元件是由微碟共振腔搭配截面漸變波導(tapered waveguide)，以單石(Monolithic)製程做在含量子點砷化鎵材料上。共振腔上下為一垂直的PIN結構，中間以三層砷化銦/砷化鎵量子點為主動層，操作波長在1140nm。與其他主動材料相比，量子點可達到極低的暗電流，有助於改善信噪比和提升響應率。 此外，使用微碟結構，除了有效減小元件的共振腔體積，以利在積體光路中應用，更大大提升了量子點的吸收效率，對光偵測器的響應率也是有著重要影響；而其模態選擇特性也有利於在波長分波多工(wavelength-division multiplexing ,WDM)上的要求。 對於本文中製作光偵測器的砷化銦量子點樣品(DO3525)，我們利用無雜質空位擴散法，以二氧化矽/二氧化鈦作披覆層，實際展現了選擇性區域量子點混合效應。期望未來能將這項技術和元件製程結合，得以彈性的調變材料發光波段，以做更廣泛的應用。

In this thesis, we demonstrate the monolithic waveguide coupled microdisk photodetector based on InAs quantum dots. By embedding InAs self-assembled quantum dots (QDs) in a GaAs-based microdisk cavity, a resonant-cavity-enhanced waveguide photodetector (PD) using monolithic processing is experimentally demonstrated around 1140 nm wavelength. The microdisk resonant cavity is a vertical PIN diode with three InAs/GaAs QD active layers. QD structures provide better performances such as ultra-low dark current, which contributes to high responsivity and signal-to-noise-ratio, in comparison with other active materials. Microdisk structures efficiently enhance the absorption of InAs QDs. In addition, their compact size makes it suitable for integrated optics. Furthermore, the wavelength selectivity of the disk resonant cavity also makes the PD preferable for wavelength-division multiplexing. Moreover, from our InAs quantum dots sample (DO3525), we have successfully demonstrated the selective area quantum dots intermixing by the IFVD technique using SiO2/TiO2 cladding layers. We expect to apply this method to our QD devices in the future.