W/Mo超晶格薄膜的微结构研究

纳米多层膜因常出现物理或力学性能的异常而成为薄膜研究的热点之一。采用ＸＲＤ和ＴＥＭ技术研究了Ｗ／Ｍｏ纳米多层膜微结构。结果表明,Ｗ和Ｍｏ由于同为体心立方结构,且晶格常数相近,由它们交互重叠形成的纳米多层膜具有柱状晶穿过调制界面外延生长的结构特征,形成多晶超晶格结构。     

核壳结构CdS：Mn/ZnS纳米晶的制备与光学性能研究

以3-巯基丙酸为稳定剂,采用共沉淀法在水相中合成了CdS∶Mn掺杂纳米晶,然后进一步将ZnS包覆于CdS∶Mn纳米晶表面,制备了CdS∶Mn/ZnS核壳结构纳米晶。利用X射线衍射（XRD）,透射电子显微镜（TEM）和紫外-可见吸收光谱（UV-Vis）对纳米晶的结构、形貌和光学性质进行了表征,发现制备的纳米晶具有优秀的单分散性,确认合成了CdS∶Mn/ZnS核壳结构纳米晶。通过荧光光谱（PL）研究了纳米晶的发光性质和光稳定性,结果表明包覆壳层后纳米晶的发光强度显著提高,最高可达8倍,且Mn2＋离子的发光峰峰位置随着ZnS壳层数的增加而红移。此外,核壳纳米晶的光稳定性大大提高。     

磁控溅射法制备的CdS:Al薄膜的性质研究

采用Al和CdS双靶共溅射的方法, 调控Al和CdS源的沉积速率, 制备出不同Al掺杂浓度的CdS:Al薄膜。通过XRD、SEM、AFM、紫外-可见透射光谱分析、常温霍尔测试对CdS: Al薄膜的结构、形貌、光学和电学性质进行表征。XRD结果表明, 不同Al掺杂浓度的CdS:Al薄膜均为六方纤锌矿结构的多晶薄膜, 并且在(002)方向择优生长。SEM和AFM结果表明, CdS:Al薄膜的表面均匀致密, 表面粗糙度随着Al掺杂浓度的增加略有增加。紫外-可见透射光谱分析表明, CdS:Al薄膜禁带宽度在2.42~2.46 eV 之间, 随着Al掺杂浓度的增加而略微减小。常温霍尔测试结果证明, 掺Al对CdS薄膜的电学性质影响显著, 掺Al原子浓度3.8%以上的CdS薄膜, 载流子浓度增加了3个数量级, 电阻率下降了3个数量级。掺Al后的CdS薄膜n型更强, 有利于与CdTe形成更强的内建场, 从而提高太阳电池效率。用溅射方法制备的CdS:Al薄膜的性质适合用作CdTe薄膜太阳电池的窗口层。     

复合结构纳米晶CdS∶Cu/CdS的制备及光学特性

在非配位溶剂中合成了高质量的CdS纳米晶核,并利用Cu²⁺离子对其进行掺杂,制备了CdS∶Cu纳米晶.通过进一步采用连续离子层吸附反应的方法对CdS∶Cu纳米晶进行表面修饰,得到CdS∶Cu/CdS复合结构纳米晶.利用X射线衍射(XRD),透射电镜(TEM),紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)对其结构、形貌以及光学性质进行了表征和分析,结果表明:所制备的复合结构CdS∶Cu/CdS纳米晶为立方闪锌矿结构;与CdS纳米晶核相比,掺杂Cu²⁺可以使其表面态发光发生红移;在CdS∶Cu纳米晶中,通过改变掺杂Cu²⁺的浓度,可以实现表面态发光在570和620nm之间的连续调节.与未经包覆的CdS∶Cu纳米晶相比,包覆层CdS增强了纳米晶CdS∶Cu的稳定性.     

过渡金属掺杂SnO_2超晶格磁学和光学性质的研究

基于密度泛函理论的第一性原理,采用全势线性缀加平面波方法 (FPLAPW)和广义梯度近似(GGA)来处理相关能,计算了n层过渡金属Cr掺杂SnO2超晶格的电子态密度、能带结构和光学性质(n=1,2,3)。结果表明,掺杂使材料均表现出了半金属性,并且导电性和磁矩随着n的增大而增强。掺杂后材料磁矩主要来源于Cr3d态,Cr的加入使O的态密度产生了自旋极化现象。在0~1.8eV处掺杂所形成的第一吸收峰的位置随着n的增加而向高能方向推移,在1.8~7.0eV处所形成峰的峰值随着n的增大而增加,在7.0~17.0eV处所形成的峰的峰值随着n的增大而减小。     

核壳结构CdS/ZnS荧光量子点的制备与荧光性能研究

以氧化镉为镉源、硫单质为硫源、油酸为配体、在十八烯体系中合成单分散的CdS纳米颗粒,研究了配体浓度对纳米微粒的生长动力学、颗粒尺寸分布的影响.采用乙基黄原酸锌作为Zn、S源的反应前体,采用逐滴滴加的方法制备了具有核壳结构的CdS/ZnS量子点,吸收光谱和荧光光谱表明CdS/ZnS纳米粒子比单一的CdS纳米粒子具有更优异的发光特性.透射电子显微镜、X射线粉末衍射、X射线光电子能谱、选区电子衍射证明ZnS在CdS表面进行了有效包覆.所制备核壳结构纳米粒子具有较好的尺寸分布,荧光发射峰半高峰宽为18～20nm,荧光量子产率达40%.     

a-Si/a-SiNx超晶格材料光学特性

采用射频磁控反应溅射技术制备不同Si层厚度的a-Si/a-SiNx超晶格材料.利用红外光谱(IR)、能谱(EDS)、X射线衍射谱(XRD)、吸收谱和光致发光(PL)谱对超晶格材料的成分、结构和发光特性进行研究.结果表明,样品的光学吸收边和PL峰随着Si层的厚度的变化而发生明显偏移,观察到了明显的量子限制效应.在氮气保护下以1000℃对样品进行热退火处理,发现Si层厚的样品退火后发光峰相对于退火前发生了蓝移,这归因于样品中nc-Si颗粒的形成.     

CdS多晶薄膜的制备及性质研究

分别采用近空间升华法和电子束蒸发法在透明导电玻璃和普通载玻片上制备了硫化镉(CdS)多晶薄膜.对制备样品的表征结果表明:(1)两种方法制备样品都沿(002)晶向择优生长,属于六方相多晶结构,但择优取向度不同;(2)CdS薄膜表面连续而致密,粒径均匀,但两种工艺制备样品的S:Cd原子比有较大差异;(3)CdS薄膜的光能隙在2.39～2.44eV之间,电子束蒸发制备样品光能隙稍小.分析认为,两种方法制备样品的上述差异可能与衬底温度、沉积时间及成膜机制的不同相关.     

Co、Mn共掺杂SnO_2超晶格的电子结构和光学性质

采用基于第一性原理的线性缀加平面波(FP-LAPW)方法,应用广义梯度近似来处理相关能,研究了Co、Mn掺杂SnO2超晶格的电子态密度、能带结构和光学性质。研究结果表明,Co、Mn掺杂使材料表现出金属性。共掺杂Co、Mn的3d电子和O的2p电子产生了强烈的杂化作用,杂化作用使Co和Mn原子的磁矩3.0μB。单掺杂Co时没有杂化作用,导致每个Co原子产生的磁矩为1.56μB。两种掺杂都在低能量区1.0 eV处形成新的介电峰,Co、Mn共掺杂与Co掺杂相比在1.5 eV处形成介电峰,吸收系数和反射系数也发生了相应的变化。     

衬底温度对柔性硫化锌薄膜结构与光学性能的影响北大核心CSCD

本文利用射频磁控溅射薄膜沉积技术在柔性聚酰亚胺(PI)、氧化铟锡(ITO)玻璃及石英玻璃衬底上制备了透明硫化锌(ZnS)薄膜。通过改变生长过程中的衬底温度,全面系统地研究了衬底温度对柔性和刚性ZnS薄膜的晶体结构、光透过率、光学常数以及表面性能影响的规律。研究表明升高衬底温度有利于形成ZnS薄膜(111)晶面的择优取向生长。不同衬底温度条件下制备的柔性和刚性ZnS薄膜在可见光波长范围内的平均光透过率均大于80%;在红外波长范围的平均光透过率达到85%。柔性ZnS薄膜在400 nm-890 nm波长范围内的光学折射率为2.21-2.56。刚性ZnS薄膜的光学折射率随着衬底温度的升高有所增加,当衬底温度为300℃时,刚性ZnS薄膜在890 nm波长处的折射率达到2.26。柔性ZnS薄膜厚度及表面粗糙度均随着衬底温度的升高而降低,当衬底温度为300℃时,柔性ZnS薄膜表面均方根粗糙度达到最小值2.99 nm。为实现高性能柔性ZnS光电器件,应控制生长柔性ZnS薄膜的衬底温度在200℃-300℃,以获得最优化的器件性能。     

不同壳层的CdS／ZnS核／壳结构量子点的温度相关荧光性质

报导了CdS／ZnS纳米晶体（NCs）的制备过程和其光学}生质。通过采用连续离子层吸附和反应技术（SILAR）,我们用少量的表面活性剂合成了不同壳层的四个样品,包括CdS核纳米晶以及具有1～3层ZnS壳的CdS／ZnS核／壳结构纳米晶体样品。发现具有一层ZnS壳的CdS／ZnS样品的荧光量子产率大约比未包覆壳层的CdS纳米晶体样品的强11倍。另外,随着壳层的增加（增至两到三层）,荧光量子产率呈现下降的趋势。对样品进行了温度相关的光谱测量,发现CdS／ZnS和CdS一样具有特殊的光学特性。     

Preparation of lanthanide doped CdS, ZnS quantum dots in natural polysaccharide template and their optical properties

Employing a biomimic method using polysaccharide as template, luminescent lanthanide ions doped CdS and ZnS quantum dots (QDs) were prepared. According to the results of TEM and absorbance, nanocrystals with an average size of 6 nm were formed under mild condition without any toxic and expensive agent applied. Differentiating from the un-doped CdS and ZnS QDs prepared in polysaccharide template, the lanthanide doped QDs exhibited obvious dopant emission in their photoluminescence spectrum. It was also found that the dopant PL became more prominent with increasing lanthanide doping concentration, while the highest PL intensity was obtained at a doping level of 1% for both of CdS and ZnS QDs. When different lanthanide ions were introduced into the CdS QDs in polysaccharide template, varied emission wavelength were able to be obtained. This study provides an easy, mild and environmental friendly alternative method to prepare doped quantum dots. In addition, the bioactivity and processabilities endowed by the polysaccharide template may expand the applications potential of this type of optical materials.     

复合结构纳米晶CdS：Cu/CdS的制备及光学特性

在非配位溶剂中合成了高质量的CdS纳米晶核,并利用Cu2+离子对其进行掺杂,制备了CdS:Cu纳米晶.通过进一步采用连续离子层吸附反应的方法对CdS:Cu纳米晶进行表面修饰,得到CdS:Cu/CdS复合结构纳米晶.利用X射线衍射(XRD),透射电镜(TEM),紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)对其结构、形貌以及光学性质进行了表征和分析,结果表明:所制备的复合结构CdS:Cu/CdS纳米晶为立方闪锌矿结构;与CdS纳米晶核相比,掺杂Cu2+可以使其表面态发光发生红移;在CdS:Cu纳米晶中,通过改变掺杂Cu2+的浓度,可以实现表面态发光在570和620nm之间的连续调节.与未经包覆的CdS:Cu纳米晶相比,包覆层CdS增强了纳米晶CdS:Cu的稳定性.     

CdSe／CdS核壳量子点拉曼光谱的表面模分析

研究了不同壳层厚度(0～5.5ML)的CdSe/CdS核壳量子点的一次和高次拉曼散射,具体分析了CdSe和CdS的表面模随着壳层厚度的变化情况.结果表明,随着壳层厚度的增加,CdSe表面模(SO1)从198cm-1频移到185cm-1,CdS的表面模(SO2)从275cm-1频移到267cm-1,并且SO1和SO2试验结果与由介电连续模型得到的理论值很接近.此外,根据CdSe表面模的频移,对随着CdS壳层厚度的增加而引起的核层(CdSe)的介电常数随环境的变化做出了修正.     

核壳结构CdS/ZnS@rGA的制备及光催化性能研究

为研究纳米CdS/ZnS@rGA复合材料在可见光下的光催化性能,采用一步溶剂热法合成了以ZnS为壳的CdS/ZnS核壳纳米粒子,将CdS/ZnS核壳纳米粒子附着在rGO纳米片上,并组装成CdS/ZnS@rGA复合气凝胶,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等对样品进行了表征,通过亚甲基蓝(MB)的光催化降解实验表明：CdS/ZnS@rGA复合气凝胶的形成不仅可以提高CdS的光稳定性,还可以增强对MB吸附能力,同时对MB的降解有明显的促进作用。可见光反应90 min, 50 mg的CdS/ZnS@rGA对100 mL 20 mg/L MB的去除率最高达到99%。经过5次循环实验,该材料仍具有较好的可重复利用性。     

Highly luminescent blue emitting CdS/ZnS core/shell quantum dots via a single-molecular precursor for shell growth

Highly luminescent blue-emitting CdS/ZnS core/shell quantum dots (QDs) were synthesized in N-oleoylmorpholine by two facile steps: first, the CdS core QDs were prepared via a simple one-pot method involving a direct reaction of Cd precursor cadmium stearate and S precursor S powder in solvent N-oleoylmorpholine; second, ZnS shells were successively overcoated on CdS core through the decomposition of single molecular precursor zinc diethyldithiocarbamate. The thickness of shell was precisely tuned by controlling drip feed speed and amount of shell precursor. The obtained CdS/ZnS core/shell QDs showed the maximum photoluminescent quantum yield of 54.8% and narrow spectra bandwidth, exhibiting high monodispersity, good color purity and long fluorescent lifetimes. The CdS/ZnS core/shell QDs with tunable emission wavelength of 424–470 nm were obtained by controlling the thickness of ZnS shell overgrown on different-sized CdS QDs, which are promising materials for blue light-emitting devices.     

Low temperature synthesis and optical property of ZnS nanotubes

Zinc sulphide (ZnS) nanotubes were synthesised via simple surfactant emulsion template under hydrothermal conditions. X-ray diffraction, scanning electron microscopy and transmission electron microscope were used to characterise the nanotubes. The results indicate that the nanotubes are composed of nanoparticles. The diameters of the nanotubes vary from 300 to 700?nm and lengths range from 1 to 2?µm. In addition, it is found that the reaction time, reaction temperature and cetyltrimethylammonium bromide play key roles in the phase and morphology control of ZnS nanotubes. Furthermore, room temperature photoluminescence was recorded to investigate the optical property of the obtained product. The stable and strong green emission band centred at 513?nm was attributed to some self-activated centres, probably vacancy states or interstitial states related to the peculiar structure.     

Studies on optical absorption and photoluminescence of thioglycerol-stabilized ZnS nanoparticles

ZnS quantum dots of size 3 nm are prepared at 303 K using ZnSO₄ and Na₂S₂O₃ precursors with thioglycerol as stabilizing agent. Cd²⁺ doped ZnS were prepared by varying doping concentration from 1 to 8 wt.%. ZnS quantum dots were mixed with CdS quantum dots of size 4 nm in the 3:1, 2:1, 1:1, 1:2, 1:3 and 1:4 M ratio. The nanoparticles were characterized by UV–vis, photoluminescence (PL), XRD and high-resolution TEM measurements. The XRD pattern, high-resolution TEM image and SAED pattern reveal that the nanoparticles are in well-crystallized cubic phase. The band gap of ZnS has increased from the bulk value 3.7 to 4.11 eV showing quantum size effect. Excitonic transition is observed at 274 nm in UV absorption and PL emission at 411 nm. Doping with Cd²⁺ red-shifts both UV and PL spectral bands and enhances the PL band of ZnS nanoparticles. Mixing CdS and ZnS quantum dots in different molar ratios shows red-shift of the band edge in the CdS/ZnS hybrid system. In the 1:1 hybrid system of CdS/ZnS nanoparticles, PL band is red-shifted and the intensity is almost doubled with respect to that of CdS nanoparticles.