砷化鎵/銻砷化鎵第二型量子井載子動力學與光學特性之研究

Carrier dynamics and photoluminescence study in type II GaAs/GaAs1-xSbx quantum well

黃孝慈(Hsiao-Tzu Huang)

指導教授 ： 林浩雄

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902962

摘要

本論文藉由進行X射線衍射以表徵GaAs/GaAs1-xSbx量子井中的成分結構和界面性質（x = 0.352,0.405）。另外利用光致發光技術、時間解析螢光光譜及光電導率等技術，來研究光學性質和載子動力學之特性。在變溫光致發光實驗中，我們可以分辨在低溫時(<200K)，發光能量主要是受到載子侷限於量子井中的影響，而高溫則是熱效應激活載子佔有較大的比例。這使得峰值在低溫時類似於GaAsSb，而高溫時接近於GaAs。透過改變激發功率的螢光光譜，我們觀察到峰值有明顯的藍移現象。在低激發時，主要是因為能隙填滿，而在高激發時則是因為能帶彎曲效應的主導，使得電子填至更高的能階造成藍移。受到了不同的載子複合機制的競爭，激發功率與發光強度會有不同的斜率關係。在時間解析螢光光譜，我們使用單數函數去進行擬和得到複合時間常數。在80-300K時，侷限能態激發至量子井的能態與電洞流失減少歐傑複合效應，使得複合效率受到影響。最後，我們觀察到光電導光譜中的輕重電洞價電帶的邊緣躍遷。而在高能量時，光電導由於表面複合增加而有下降的現象。

關鍵字

藍移 ； 載子動力學 ； 光電導 ； 光致發光 ； 量子井

並列摘要

X-ray diffraction (XRD) is performed to characterize the compositional structure and interfacial properties within GaAs/GaAs1-xSbx single quantum well with (x=0.352, 0.405). Optical properties and carrier dynamics are then investigated by photoluminescence(PL) as a function of temperature, power, time-resolved photoluminescence (TRPL) and photoconductivity (PC). In temperature-dependent PL, the effect of carrier confinement in QW and the thermal activation cause emission peaks to be dependent on GaAsSb at low temperature and GaAs above 200K. A large blueshift is observed with increased excitation powers due to band filling of localized states at low intensities and band bending at high intensities. The sublinear relationship between the integrated intensities and power at different temperatures also reveal the competition between various recombination mechanisms. A single exponential decay function is fitted to obtain the carrier decay time and the effect of hole leakage reducing Auger recombination and thermal activation of localized states affect the recombination rate in the range of 80-300K. Finally, the band edge transition for heavy hole and light hole in PC spectra are identified at low temperature and PC intensity subsequently reduces due to surface recombination at high energy.

並列關鍵字

blueshift ； carrier dynamics ； photoconductivity ； photoluminescence ； quantum well

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