氮化銦磊晶層之光激螢光研究

Photoluminescence properties of InN epilayers

吳佩芳(Pei-Fang Wu)

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/cycu200700108

摘要

摘要

本文利用光激螢光光譜與拉曼光譜來分析氮化銦磊晶層的基本光學性質。我們發現氮化銦磊晶層經由快速熱退火處理後，其光學與電性品質皆獲得改善。我們認為在熱退火過程中，由於銦的空缺增加導致補償效應，因而使載子濃度下降。由變溫光激螢光光譜中，發現隨溫度增加而能量峰值有下降、上升、下降等現象，此S型行為是因為載子受到溫度的活化，脫離了原先的侷域態而躍遷至高能量能態。根據變溫的載子輻射生命期，我們發現經熱退火200 oC、300 oC處理的氮化銦由低溫時的侷限態載子受熱跳脫為三維空間自由載子；經熱退火400 oC、500 oC處理的氮化銦則由低溫時的侷限態載子受熱跳脫為二維空間自由載子。我們認為這是由於樣品表面電子聚集所導致。根據室溫拉曼光譜，發現隨熱退火處理的溫度越高，A1(LO)模態越不對稱且有紅位移，這是由於銦的空缺變多，且壓應力獲得釋放所導致。

關鍵字

拉曼 ； 氮化銦 ； 光激螢光

並列摘要

Abstract

We investigated the optical properties of InN epilayers using photoluminescence (PL), time-resolved PL (TRPL) and Raman scattering. We suggest that the formation of compensating acceptors (indium vacancies) after rapid thermal annealing (RTA) is responsible for the improvement of the optical and electrical qualities in InN epilayers. Based on the temperature dependence of PL spectra, we observed an “S-shaped” behavior of the PL-peak energy as the temperature is increased. We suggest that the localized carriers can be delocalized by thermal activation. Based on the temperature dependence of radiative lifetimes in InN, we suggest that the localized carriers can be delocalized at elevated temperature and become nearly three-dimensional for the InN annealed with the temperatures of 200 and 300 oC. Due to surface electron accumulation, the localized carriers become nearly two-dimensional (2D) for the InN annealed with the temperatures of 400 and 500 oC. The shift of the A1(LO) phonon mode in Raman spectrum is found to be related to the compressive strain within the InN/GaN interface. The asymmetric ratio of the A1(LO) phonon mode increases with increasing the annealing temperature due to the formation of indium vacancies after RTA.

並列關鍵字

Raman ； InN ； PL

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參考文獻