有機金屬氣相磊晶成長之氮化銦鎵/氮化鎵多重量子井 結構之光學特性

Optical Properties of InGaN/GaN Multi-Quantum Wells Structure Grown by Metalorganic Chemical Vapor Deposition

李振昇(Zhen-Sheng Lee)

指導教授 ： 馮哲川

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.10611

摘要

本論文主要分析氮化銦鎵/氮化鎵多重量子井的光學特性，透過變
溫、時間鑑別光激螢光頻譜、光激螢光激發光譜、X 光繞射以及穿透式電子顯微鏡實驗來研究其光學特性。
在第一部份中，我們研究不同銦含量之量子井藍光及藍綠光之氮化銦鎵/氮化鎵多重量子井樣品的光學特性。由光激螢光光譜之溫度變化比較中，可以知道在光激螢光光譜中所觀察到的量子井相關訊號，並不完全是來自於能帶間躍遷的訊號，有一部分可能是來自於在氮化銦鎵量子井中銦組成的不均勻性，造成位能波動起伏所形成的侷限態的躍遷訊號。隨著溫度升高訊號有紅位移的趨勢並伴隨著半寬的增加。利用活化能的經驗公式模擬可以知道氮化銦鎵/氮化鎵多重量子井的活化能。然後利用時間鑑別光激發光頻譜，當氮化銦鎵/氮化鎵多重量子井之銦含量增加，衰退時間較大。然後透過光激螢光激發實驗，我們觀察到很大的史托克位移，這主要是由於銦濃度變化與量子侷限史塔克效應的影響。最後由X 光繞射及穿透式電子顯微鏡實驗，我們可以測定樣品的量子井厚度以及量子井中的銦
含量。
在第二部份中，我們研究不同量子井寬度藍光之氮化銦鎵/氮化鎵多
重量子井樣品的光學特性。由光激螢光光譜的溫度變化，我們發現氮化銦鎵量子井相關訊號存在著一個不尋常的發光現象。隨著溫度的升高，其峰值能量的改變呈現著一個S型的能量變化。利用能帶尾端侷限態之模型，即導電帶與價電帶尾端之狀態密度以高斯分佈來描述分析之。然後利用時間鑑別光激發光頻譜，當氮化銦鎵/氮化鎵多重量子井之量子井寬度增加，量子井內的震盪強度較小，衰退時間較大。

關鍵字

光激螢光光譜 ； 光激螢光激發光譜 ； 時間鑑別光激螢光光譜

並列摘要

In this thesis, temperature-dependent and time-resolved photoluminescence (PL), photoluminescence excitation (PLE), X-ray diffraction (XRD), and transmission electron
microscopy (TEM) experiments were performed to study the optical property of blue and blue-green light-emitting diodes (LEDs) which based on the InGaN/GaN muti-quantum
wells (InGaN/GaN MQWs) structure. Firstly, we studied the optical properties of InGaN/GaN MQWs with different indium
(In) composition. The temperature-dependent PL results show that the signal from InGaN/GaN MQWs was influenced by two kinds of factors. One is the band to band
transitions within InGaN MQWs; another is the localization effect result from the non-uniformity of the In composition in In-rich samples. While the temperature increases, the full width half maximum (FHWM) of PL signal increases and tends to shift toward the long wavelength (red shift). The activation energies (Ea and Eb) of the InGaN MQWs samples were obtained by using the fitting formula of activation energies. InGaN/GaN MQWs are investigated by the time-resolved photoluminescence and revealed that the higher In composition, and decay time would be longer. A large Stokes shift (SS) was observed from the results of PLE experiment. The large Stokes shift could be attributed to the variation in indium composition or the quantum confined Stark effect (QCSE).
Moreover, from the XRD and TEM experimental results, we could determine the thickness of five periodic layers and In composition of the samples.
Secondly, we studied the optical properties of InGaN/GaN MQWs with different well width. The anomalous temperature dependency of the peak energy was exhibited, and an
S-shaped behavior of PL spectra was observed with increasing temperature. Using the Gaussian-like distribution of band-tail model, we could analyze the temperature-dependent emission energy. Besides, the less oscillator strength in the QWs arose from thicker well
width, and finally led to the longer decay time by time-resolved photoluminescence.

並列關鍵字

Photoluminescence ； Photoluminescence Excitation ； Time-resolved Photoluminescence

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