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Title: 飛秒激發-探測光譜在a面氮化銦薄膜的研究
Femtosceond pump-probe spectroscopy in a-plane InN
Authors: Cheng-Yu Chang
張正裕
Contributors: NTOU:Institute of Optoelectronic Sciences
國立臺灣海洋大學:光電科學研究所
Keywords: 氮化銦;激發-探測;熱載子
InN;pump-probe;hot carrier
Date: 2009
Issue Date: 2011-07-04
Abstract: 我們以時解析光學激發-探測反射系統,研究a面氮化銦薄膜的載子動力學。我們利用雷射功率來改變載子濃度,觀察熱載子能量鬆弛率與熱載子濃度的關係。再者為改變波長量測,觀察在固定載子濃度下,不同熱載子能量鬆弛率與熱載子能量的關係。實驗中我們觀察到熱載子能量鬆弛率與載子濃度約呈1次方的關係,因此我們推斷電子和電子的散射機制在能量鬆弛過程中佔有很大的因素。載子復合過程的實驗結果我們則發現主要是由缺陷捕抓和歐傑復合過程所支配,其缺陷復合時間各為303ps、434ps和909ps,歐傑係數各別為4.9×10-11(cm3/s)、5.4×10-11(cm3/s)及3.1×10-11(cm3/s)。在改變雷射波長的實驗量測,載子濃度8.8×1018cm-3時熱載子能量鬆弛率和熱載子能量呈0.7次方的關係。載子濃度1.4×1018cm-3時熱載子能量鬆弛率和熱載子能量呈0.6次方的關係。載子濃度2.1×1018cm-3時熱載子能量鬆弛率和熱載子能量呈0.5次方的關係且此結果與理論預測相同,然而熱載子能量鬆弛率和熱載子能量的關係下降原因還不是很清楚,因此尚無法完全解釋。
We used a femtosecond time-resolved pump and probe reflectivity measurement to investigate the carrier dynamics of a-plane indium nitride (InN). Laser power was used to modify carrier density to observe the interaction between the hot carrier relaxation rate and carrier density. Wavelength range was also altered to observe the interaction between the relaxation rate of hot carrier energy and kinetic energy in normal carrier density circumstances. In this study, the authors observed that the hot carrier relaxation rate and hot carrier density are in direct ratio to one another. Thus, it was predicted that electron-electron scattering is a crucial element in the hot carrier relaxation process. The carrier recombination process was seemingly influenced by the defect recombination process and the Auger recombination process. The defect recombination process was completed in 303ps, 434ps, and 909ps respectively; while the Auger recombination was completed in 4.9×10-11(cm3/s), 5.4×10-11(cm3/s), and 3.1×10-11(cm3/s). In the study involving the modification of the laser wavelength, the hot electron relaxation rate and hot electron energy were at a 0.7 ratio when the carrier density was at 8.8×1018cm-3; when the carrier density was at 1.4×1018cm-3, the hot electron relaxation rate and hot electron energy were at a 0.6 ratio; when the carrier density was at 2.1×1018cm-3, the hot electron relaxation rate and hot electron energy were at a 0.5 ratio. These results were similar to what was predicted theoretically; however, the reason behind the fall in the interaction between the hot energy relaxation rate and hot energy were not clear and cannot be fully accounted for.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M96880045
http://ntour.ntou.edu.tw/ir/handle/987654321/17749
Appears in Collections:[Institute of Optoelectronic Sciences] Dissertations and Theses

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