- 學位論文
多波段量子點紅外線偵測元件之光電特性
The Optical and Electrical Properties of Multi-Color Quantum Dot Infrared Photodetector
摘要
藉由在砷化銦量子點上誘W2奈米的鋁砷化鎵，使得3 ML的砷化銦/鋁砷化鎵/砷化鎵量子點紅外線偵測器具有5.6、9.5以及15.7 μm多波段之響應。根據隨雷射必v變化之光激放光頻譜(PL)可得知，短波長波段的響應是從大顆或是小顆量子點的基態到砷化鎵傳導帶造成的，而長波長波段的響應則是大顆量子點的基態到激發態所貢獻的。此外，由2.2 ML的砷化銦/鋁砷化鎵/砷化鎵量子點紅外線偵測器可觀察到較高的響應值以及負微分電導的效應。本文中同樣詳細探討具有鋁砷化鎵以及銦鋁砷化鎵阻擋層的砷化銦/砷化鎵量子點紅外線偵測器。其中不同成分的銦鋁砷化鎵阻擋層所造成之影響亦被研究。增加阻擋層中銦的濃度，位障高度便會降低。而使用較低的阻擋層，其目的是減少暗電流，但仍保持相當的光電流。
並列摘要
By capping the InAs quantum dots (QDs) with 2 nm AlGaAs layer, the 3 monolayer (ML) InAs/AlGaAs/GaAs quantum dot infrared photodetector (QDIP) exhibits multi-peaks at 5.6, 9.5, and 15.7 μm, respectively. According to the laser power dependent PL spectra, the short-wavelength peaks are responsible for the large and small QDs size distributions from the ground state to GaAs conduction band, respectively. However, the long-wavelength peak is attributed to the bound-to-bound transition from ground to first excited state of large QD. The properties of 2.2 ML InAs/AlGaAs/GaAs QDIPs are also investigated. The phenomena of high responsivity and negative differential conductance (NDC) are observed. Then, the characteristics of the QDIP clamping with Al0.3Ga0.7As and In0.17Al0.25Ga0.58As blocking barrier layers are discussed. Besides, QDIPs with two InxAlyGa1-x-yAs blocking layers are also investigated. When the In composition increases, the blocking barriers would be lower. The purpose is to decrease the dark current without affecting photocurrent.