摘要
应用反胶束法制备了稀磁半导体 Cd1 - x Mnx S量子点 .量子点的大小可通过改变ωo 值 ( wo=[水 ]/ [表面活性剂 ])来控制 .高分辨透射电镜的分析结果表明 ,量子点呈单分散性 ,是几乎没有缺陷的单晶体 .量子点的大小约为 4.8～ 6nm,随 wo 值增大而增大 .电子能谱 ( EDS)测定结果表明 ,Mn2 +离子在量子点中的摩尔分数为 1 .5 % .由电子自旋共振 ( ESR)分析确定一部分 Mn2 + 离子取代 Cd2 + 离子位置而位于晶格 ,另一部分 Mn2 +离子位于 Cd1 - x Mnx S的表面或间隙位置 .吸收光谱显示 ,随着量子点变小 ,吸收带边发生蓝移 ,显示明显的量子尺寸效应 .光致荧光光谱分析表明 ,发光峰属于 Mn2 + 的 4 T1 -6 A1 跃迁 ,而且随着ωo 和粒径的增大 ,发光峰从 2 .2 6,2 .1 0 ,2 .0 5 e V红移到 1 .88e V;其发光峰偏离 2 .1 2 e V,主要是由于 Mn2 + 离子位于扭曲的四面体晶体场所致 .
Incorporation of diluted magnetic semiconductors (DMS) in quantum confined systems opens new possibilities for the spin-dependent electronics due to the combination of the exchange interaction and the quantum confinement. In this work, we focus on the synthesis and optical properties of Cd 1-xMn xS quantum dots (QDs). Cd 1-xMn xS quantum dots (QDs) were prepared via a reverse micelles. The size of dots was controlled by changing the ratio of w o (w o=/). A series of Cd 1-xMn xS QDs samples with w o varying from 3.5 to 5.5 were prepared. A high-resolution electron transmission microscopy (HRTEM) study of QDs with w o=3.5 shows that the QDs are nearly mono-dispersed with an average diameter around 4.8 nm and the QDs are defects-free single crystals. The Cd 1-xMn xS QDs size is varying from 4.8, 5.1, 5.3 to 6.0 nm with w o varying from 3.5, 4.5, 5.0 to 5.5. The molar fraction of Mn 2+ in the Cd 1-xMn xS dots is about 1.5% with respect to (Mn 2++Cd 2+) determined by X-ray energy dispersion spectroscopy. Electron spin resonance spectroscopy shows that Mn 2+ ions are in tetrahedral sites indicating that Mn 2+ are incorporated into the CdS lattice. The absorption spectra of these samples exhibit a well-defined excitonic peak located from 2.88 eV to 3.28 eV corresponding to the different values of w o. The longer wavelength of the absorption peak is exhibited with the larger w o. Most interestingly, the photoluminescence emission peaks are red-shifted from 2.26 eV to 1.88 eV with increasing the w o values from 3.5 to 5.5. These emission peaks are believed to originate from the Mn 2+ 4T 1- 6A 1 transitions in associated states.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第9期1593-1596,共4页
Chemical Journal of Chinese Universities
基金
香港研究基金会基金 (批准号 :H KUST60 69/0 2 P)资助 .
关键词
量子点
稀磁半导体
Cd1-xMnxS
反胶束
光致荧光
Quantum dots
Diluted magnetic semiconductors
Cd 1-xMn xS
Reverse micelles
Photoluminescence
