碲化錳鋅磊晶層及奈米結構之成長與特性分析

Growth and Characterization of Zn1-xMnxTe Epilayer and Nanostructure

江文誠(Wen-Cheng Chiang)

指導教授 ： 周武清

中原大學/理學院/應用物理研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200141

摘要

利用分子束磊晶法在砷化鎵 (001) 基板上成長錳的濃度介於0 % 與26.8 % 之間的碲化錳鋅磊晶層，並且以反射光譜、穿透光譜及光激螢光譜來探討磊晶層的光學特性。由低溫下光激螢光譜的結果得知，當錳的濃度增加時，磊晶層的能隙與半強度頻寬皆會隨著變大。除此之外，在變溫光激螢光譜的結果中發現，當溫度升高時，光激螢光譜的譜峰會產生紅位移的現象。藉由亞倫尼斯圖法 (Arrhenius Plot) 計算磊晶層中激子的活化能，得知激子的活化能會隨著錳濃度的增加而逐漸變大。再利用瓦希尼 (Varshni) 與歐德尼爾 (O’Donnell) 經驗公式對變溫光激螢光譜的實驗數據做擬合，由擬合結果可以得到與聲子能量相關的擬合參數。另外也以聲學聲子、縱向光學聲子以及雜質間的交互作用作為散射模型的理論參數，對變溫光激螢光譜訊號的線寬做擬合，發現當錳的濃度增加時，樣品中的雜質束縛能也會隨著變大。
除了碲化錳鋅磊晶層之外，我們也利用分子束磊晶法在砷化鎵 (001) 基板上成長錳的濃度為 11.7 % 的碲化錳鋅量子點結構，以原子力顯微術觀察樣品的表面形貌，並且利用光激螢光譜研究其光學特性。由光激螢光譜中得知碲化錳鋅量子點的躍遷能量大約是在2.296 電子伏特，而且不會隨著碲化錳鋅量子點的平均覆蓋厚度的不同而有所改變。除此之外，隨著碲化錳鋅量子點的平均覆蓋厚度變厚，錳離子的躍遷能量會有遞減的趨勢。藉由原子力顯微術以及光激螢光譜的結果，我們可以大膽推測碲化錳鋅/硒化鋅/砷化鎵這個量子點系統是屬於一開始就是三維成長的Volmer-Weber 模式 ( V-W mode )。

關鍵字

碲化錳鋅 ； 二六族稀磁性半導體 ； 奈米結構 ； 分子束磊晶 ； 光激螢光

並列摘要

Zn1-xMnxTe epilayers with Mn concentration ranges from 0 to 0.268 and self-assembled Zn0.883Mn0.117Te quantum dots (QDs) were grown on GaAs (001) substrates by molecular beam epitaxy (MBE). Optical properties of the epilayers were studied using reflectivity (R), transmission (T), and photoluminescence (PL) spectroscopy. From the PL spectra, the energy gap and the full width at half maximum of the epilayer show an increase with the Mn concentration. As the temperature was increased, a red shift of the PL peaks was observed. Varshni and O'Donnell relations which mimic the temperature dependence of semiconductor energy gaps were used to fit the experimental data. From the fitted results, phonon energy related fitting parameters were obtained. The exciton activation energy of the epilayer was determined by the plots of logarithmic integrated PL intensity versus inverse temperature. Accordingly, it increases with Mn concentration. The temperature dependent of PL line-width was fitted by the acoustic phonon, longitudinal optical phonon and impurity interaction parameters. From the fitted results, the impurity binding energy was found increasing with Mn concentration.
For self-assembled Zn0.883Mn0.117Te QDs, surface morphology was studied by atomic force microscopy (AFM). The optical properties of samples were studied by photoluminescence (PL) spectroscopy. The emission from Zn0.883Mn0.117Te QDs is around 2.296 eV and it doesn’t move with the averaged Zn0.883Mn0.117Te coverage. Further, the Mn2+ transition decreases with the average Zn0.883Mn0.117Te coverage. Three-dimensional Volmer-Weber growth mode is identified from the results of AFM and PL spectra.

並列關鍵字

ZnMnTe ； nanostructure ； Ⅱ-Ⅵ diluted magnetic semiconductors ； Molecular Beam Epitaxy ； photoluminescence

參考文獻

and J. Kossut, Volume Editors, Semiconductors and Semimetals, Vol. 25

[1.3] N. Samarth and J. K. Furdyna, Pro. IEEE, 78, 990 (1990).

[1.4] S. Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990).

Appl. Phys. Lett. 73, 363 (1998).

[1.6] N. A. Gershenfeld and I. L. Chuang, Science, 275, 350 (1997).