本論文共論述了五片不同元件結構的砷化銦/砷化鎵量子點紅外線偵測器(quantum dot infrared photodetector)，樣本是由Riber Epineat固態源分子束磊晶成長在(100)方向的半絕緣砷化鎵基板上。由量子點均勻分佈的原子力顯微鏡影像上觀察到1 x 1011 cm-2的高量子點密度和7.4 nm的短平均量子點鄰近間距。由光激發螢光譜可區別出三個不同的能階，此現象可歸因於填態效應(state filling effect)。而潤濕層(wetting layer)在位障態和本地量子點態位間可形成與媒介電子的互動。由被占據的量子點態位到潤濕層或連續態之間的變遷形成紅外光偵測，因此封裝後的量子點紅外線偵測器響應光譜和經由潤濕層能量位移的光激發螢光譜展現出相同的能量位置。本論文中研究了10層和30層的砷化銦/砷化鎵量子點紅外線偵測器。30層的元件暗電流較低可歸因於量子點層數的增加使位障總厚度隨之增加。量子點紅外線偵測器的暗電流隨著溫度快速增加，這是由於其對溫度呈指數的依賴性。因此背景限制性能(background-limited performance)溫度可由變溫的電壓電流量測觀察到。由於高活化能(activation energy)的30層元件可有效抑制高溫的暗電流，故30層元件可觀察到60 K的高背景限制性能溫度。結果當10層元件僅能在50 K溫度下偵測到響應度時30層元件仍可在100 K溫度下偵測到響應度。在較多層數的元件可觀察到暗電流的抑制和響應度的增加。而為了研究量子點摻雜密度對量子點紅外線偵測器性能的影響，也探究了量子點摻雜密度由2 x 1018 cm-3、1 x 1018 cm-3、5 x 1017 cm-3到無摻雜之間變化的元件。在所有矽摻雜元件中光激發螢光譜基於填態效應展現出多峰值放射，然而在無摻雜元件中僅展現出單一峰值。活化能隨著摻雜濃度的減少而增加，故低量子點摻雜濃度可有效抑制暗電流。無摻雜元件有最高的背景限制性能溫度是由於其擁有很高的能量位障，故可觀察到200 K的最佳操作溫度。由於較低的摻雜濃度擁有較高的能量位障，其不僅僅有效地抑制了暗電流但同時也抑制了光電流。所以量子點紅外線偵測器的量子點摻雜濃度必定存在一最佳值可供設計。

Five InAs/GaAs quantum dot infrared photodetector (QDIP) samples with different device structures are discussed in the thesis. The QDIP samples are grown on semi-insulating (100) GaAs substrate by Riber Epineat solid source molecular beam epitaxy (MBE). High dot density of 1 x 1011 cm-2 and short average distance between neighboring quantum dots of 7.4 nm are observed from the uniform quantum dot distribution atomic force microscopy (AFM) image. Three different energy levels are distinguished from the photoluminescence (PL) spectra. The phenomenon is attributed to the state filling effect. The wetting layer formed and mediated the electronics interaction between the barrier states and the localized quantum dot states. Transitions from the occupied quantum dot states to the wetting layer or to the continuum states will result in infrared detection, such that the response signals of a fabricated QDIP devices exhibit the same energy position as the shifted PL spectra relative to the energy of wetting layer. 10- and 30-period InAs/GaAs QDIPs are investigated in the thesis. Lower dark current for 30-period device is attributed to the increase of quantum dot period such that the total barrier thickness is increased. The dark current of the QDIP increases rapidly with temperature, which is due to its exponential dependence on temperature. Such that the background-limited performance (BLIP) temperature can be observed from the temperature varying current-voltage measurement. Since the dark current at higher temperature can be inhibited effectually by higher activation energy in 30-period device, higher BLIP temperature of 60 K for 30-period device can be observed. As a result, 30-period device can still detect the spectral response at 100K while 10-period device can only detect the spectral response at about 50 K. The depression of dark current and the enhancement of responsivity are observed for sample with higher period numbers. In order to investigate the effect of doping density within quantum dots to the performance of QDIP, wafers with InAs quantum dot doping densities varied from 2 x 1018 cm-3, 1 x 1018 cm-3, 5 x 1017 cm-3 to undoped are also investigated. In all silicon doped samples, the PL spectra emitted from quantum dots show multi-peaks emission base on the state filling effect. However undoped sample exhibits only a unique peak. The activation energy increases with decreasing quantum dot density. Such that the dark current can be inhibited effectually with lower quantum dot doping density. The undoped device has the highest BLIP temperature because of its high energy barrier, such that the best operation temperature of 200 K is observed for undoped device. Since higher energy barrier with lower quantum dot doping density not only inhibit the dark current effectually, but also inhibit the photocurrent. There must be an optimum quantum dot doping density of QDIP to design.

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