砷化銦量子點與氮化銦磊晶層之光學特性研究

Optical properties of InAs quantum dots and InN epilayers

羅明華(Ming-Hua Lo)

指導教授 ： 沈志霖

中原大學/理學院/應用物理研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600292

摘要

本文利用光激螢光與時間鑑別光激螢光來研究砷化銦量子點與氮化銦磊晶層之光學特性研究。觀察到砷化銦量子點第一激發態與基態載子穿隧時間隨著砷化銦鋁厚度增加有增長的趨勢，與WKB模型的預測相吻合。載子穿隧時間在約90 K~120 K為最短，此現象可由砷化銦量子點激發態能量與砷化銦鎵基態能量最為接近時共振穿隧現象來解釋。
在10 K下氮化銦磊晶層螢光衰減時間為單一指數形式。根據不同能量位置載子生命期，可推測在價帶尾端有侷域化的現象，其侷域深度約為8.39 meV。我們觀察到螢光能量位置隨溫度增加有S型趨勢，原因為激子受到溫度的活化脫離了原先的侷域態躍遷至高能態，由公式可擬合侷限深度約為7.96 meV。不同溫度下載子生命期可算出活化能為8.10 meV，證明此溫度變化過程中載子為逆侷域化的趨勢。根據自由電子再結合能帶(Free Electron Recombination Band)理論模型可完整的解釋氮化銦磊晶層之載子複合機制，並計算出能帶邊緣侷限的深度為7.98 meV。

關鍵字

砷化銦 ； 氮化銦 ； 量子點 ； 侷域化

並列摘要

The optical properties of InAs quantum dots and InN epilayers were studied by using photoluminescence (PL) and time-resolved photoluminescence (TRPL). The tunneling time of the first excited state and ground state in InAs quantum dots increases by increasing the InAlAs thickness. The tunneling time is shortest about 90 ~ 120 K in the temperature range. An enhancement of the resonant tunneling escape is observed and attributed to the coupling of the first-excited state of InAs quantum dots and the ground state of InGaAs quantum well.
The PL intensity of InN epilayers shows a single exponential decay at 10 K. Based on the emission-energy and temperature dependent of carrier lifetimes, we demonstrate the carrier localization, the localized depth of about 8.39 meV. We observed an S-shaped of temperature dependent of the peak energy for InN PL with increasing temperature. In addition, obtain an activation energy of 8.10 meV from temperature dependent of PL decay times, we suggest that the localized excitons can be delocalized by increasing the temperature. Based on the free electron recombination band model, a localized depth of about 7.98 meV can be obtained which is in agreement with experiment result.

並列關鍵字

InAs ； quantum dots ； localize ； InN

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