砷化銦量子點與氮化銦磊晶層之載子動力學

Carrier dynamics of InAs quantum dots and InN epilayers

陳雅萍(Ya-Ping Chen)

指導教授 ： 沈志霖

中原大學/理學院/應用物理研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700335

摘要

摘要

本文研究了不同量子點層數的砷化銦/砷化鎵量子點與氮化銦磊晶層的載子動力學。對於不同層數砷化銦/砷化鎵多層量子點，我們觀察到溫度在10-180K時載子生命期有增長的趨勢，直至溫度大於180K之後，載子生命期開始減短。此現象可用一個經由聲子協助致使量子點基態和連續態間發生躍遷之理論模型來解釋。由實驗結果得知存在於自聚性砷化銦量子點中之連續態在載子捕捉機制中扮演很重要的角色。
我們利用光激螢光光譜來探討氮化銦磊晶層中載子鬆弛的機制。實驗中所觀察到電子溫度的變化，以一個建立在電子損失能量鬆弛至導帶的主要機制為電子和聲子交互作用的理論模型來解釋。由公式可模擬出低溫下A1(LO)模態的聲子生命期為1.01ps，與理論公式算出之值有極大的差異，此差異是來自於熱聲子效應的作用。氮化銦磊晶層中A1(LO)模態的聲子生命期隨著溫度增加而減小，此現象顯現出隨著溫度增加，A1(LO)模態的聲子以不對稱的形式衰減成一個E2(high)模式的聲子和一個小能量的聲子。

關鍵字

聲子生命期 ； 載子生命期 ； 光激螢光 ； 氮化銦 ； 砷化銦量子點

並列摘要

Abstract
We investigated carrier dynamics of electronic vertical coupling InAs/GaAs multilayer quantum dots (QDs) and InN epilayers. For InAs/GaAs multilayer QDs with multilayer numbers (N) from N=1 to N=30, the carrier lifetime increases with temperature from 10K to 180K, and then decreases as the temperature increases further above 180K. This behavior is well explained a model that is based on the phonon-assisted transition between the QD ground state and the continuum states. This result reveals the continuum states in self-assembled InAs QDs play an important role in the carrier capture processes.
We studied the energy relaxation of electrons in InN epilayers using photoluminescence (PL). It is found the measured electron temperature variation can be explained by a model based on the energy relaxation of electrons due to the LO phonon scattering. The A1(LO) phonon lifetime at 10K is fitted to be 1.01 ps, which is higher than the theoretical phonon lifetime. This deviation is attributed to the presence of the hot phonon effect. The A1(LO) phonon lifetime in InN decreases with increasing temperature. This tendency illustrates the A1(LO) phonon decays asymmetrically into a high-energy phonon and a low-energy phonon.

並列關鍵字

phonon lifetime ； InAs quantum dots ； PL ； carrier lifetime ； InN

參考文獻

[17] Olga L. Lazarenkova and Alexander A. Balandin, J. Appl. Phys., 89, 5509 (2001).

[33] N. Balkan, R. Gupta, M. E. Daniels, B. K. Ridley, and M. Emeny, Semicond. Sci. Technol. 5, 986 (1990)

[39] ]K. T. Tsen, Juliann G. Kiang, D. K. Ferry, Hai Lu, William J. Schaff, Hon-Way Lin, and Schangjr Gwo, Appl. Phys. Lett. 90, 152107 (2007)

[9] V. Y. Malakhov: Proc. SPIE 3938, 131 (2000)

[16] Michael Jupina and Elsa Garmire, Appl. Phys. Lett. 60, 686 (1992).