掺杂对锗纳米晶薄膜电输运的影响

利用离子注入然后退火的方法制备镶嵌有锗纳米晶的二氧化硅复合膜,再利用中子嬗变方法,对镶嵌有锗纳米晶的二氧化硅复合膜进行精确均匀掺杂,用激光拉曼散射测量表征锗纳米晶的存在,测量嬗变掺杂前后样品的I-U曲线和lnR-1/T曲线.结果表明:掺杂样品未退火时电阻极大,退火后电阻明显减小,但比未掺杂时大;其它条件相同时,锗的注入量越大,纳米晶层的电阻越小;在掺杂样品的低温I-U曲线中发现台阶.     

嵌入SiO2薄膜中的GeO和Ge纳米晶光致发光的研究

作者通过离子注入法得到了镶嵌于SiO2薄膜中的Ge纳米晶,并通过系统的氧化性或还原性退火处理,以改变样品中Ge的氧化物成分组成．分析了不同样品在室温下的光致发光(PL)特性,并结合XRD分析表明：300与400nm附近的荧光峰的发光机制是GeO(nc-GeO)纳米晶发光,而不是GeO的缺陷发光;570nm附近的荧光峰的发光机制为Ge纳米晶(nc-Ge)发光,而不是Ge及Si界面的缺陷发光．     

Energy transfer process between Eu3+ and wide-band-gap SnO2 nanocrystals in silica films studied by photoluminescence excitation and time-resolved photoluminescence techniques

Eu3+ions embedded in silica thin films codoped with SnO2 nanocrystals were fabricated by sol–gel and spin-coating methods.SnO2 nanocrystals with controllable sizes were synthesized through precisely controlling the Sn concentrations.The influences of doping and annealing conditions on the photoluminescence intensity from SnO2 nanocrystals are systematically investigated.The effective energy transfer from the defect states of SnO2nanocrystals to nearby Eu3+ions has revealed by the selective photoluminescence excitation spectra.The efficiency of the Forster resonance energy transfer is evaluated by the time-resolved photoluminescence measurements,which is about 29.1%based on the lifetime tests of the SnO2emission.     

ZnS：Tb／SiO2核壳结构纳米晶的光学性质

用微乳液法合成了ZnS：Tb／SiO2核壳结构纳米晶,并通过X射线粉末衍射（XRD）、透射电子显微镜（TEM）、荧光光谱等手段对产物的结构、尺寸、形貌、荧光特性进行了表征。结果表明,ZnS：Tb纳米晶的粒径为3nm,ZnS：Tb／SiO2核壳结构纳米晶的粒径为5nm左右,这样就得出壳的厚度约为1nm。在ZnS：Tb／SiO2核壳结构纳米晶的发射光谱上可以观察到有5个发射峰为460、489、544、584和620nm,分别对应ZnS基质的发光和Tb^3＋离子的^5D4→^7F6、^5D4→^7F5、^5D4→^7F4、^5D4→^7F3跃迁。     

Ordering and self-organization in nanocrystalline silicon

The spontaneous formation of organized nanocrystals in semiconductors has been observed during heteroepitaxial growth and chemical synthesis. The ability to fabricate size-controlled silicon nanocrystals encapsulated by insulating SiO2 would be of significant interest to the microelectronics industry. But reproducible manufacture of such crystals is hampered by the amorphous nature of SiO2 and the differing thermal expansion coefficients of the two materials. Previous attempts to fabricate Si nanocrystals failed to achieve control over their shape and crystallographic orientation, the latter property being important in systems such as Si quantum dots. Here we report the self-organization of Si nanocrystals larger than 80 A into brick-shaped crystallites oriented along the (111) crystallographic direction. The nanocrystals are formed by the solid-phase crystallization of nanometre-thick layers of amorphous Si confined between SiO2 layers. The shape and orientation of the crystallites results in relatively narrow photoluminescence, whereas isotropic particles produce qualitatively different, broad light emission. Our results should aid the development of maskless, reproducible Si nanofabrication techniques.     

Ge量子点材料的制备工艺研究

采用射频磁控技术,用Ge、SiO_2的复合靶制备锗纳米晶镶嵌在二氧化硅中的复合薄膜.作为量子点的Ge纳米晶粒的尺寸是决定这类材料物性的关键,因而研究对镶嵌在SiO_2中的Ge晶粒尺寸调制的工艺十分重要.本文研究了制备过程中各种工艺参数与薄膜中Ge晶粒尺寸的关系.结果表明通过溅射时控制基片温度能有效地对锗晶粒尺寸进行调制.     

Ge纳米结构的制备技术与发光特性研究进展

Si基纳米发光材料与器件的研究是目前半导体光电子技术领域中的一个活跃前沿.除了Si纳米晶粒、Si量子点和Si/SiO2超晶格等Si纳米结构之外,属于同族元素的Ge纳米结构也因其所具有的优异特性,而呈现出良好的发光性能.评述了Ge纳米结构的制备方法与发光特性在近年内取得的研究进展.     

Luminescent Cu doped CdTe nanocrystals via cation exchange of Cu7Te5 nanocubes: From undoped to doped emission

In II-VI group, the doping in CdTe nanocrystals (NCs) is more difficult than other chalcogenides. In this communication, CdTe nanocrystals containing Cu impurities were carefully synthesized based on controlled reverse cation exchange process between as-prepared Cu₇Te₅ nanocubes and Cd²⁺ ions. By well-defined Cu₇Te₅ nanocubes, the obtained CdTe NCs kept the original morphology. The concentration of Cu impurities in CdTe NCs was controlled by the regulation such reverse cation exchange. Additionally, the regulation from band gap (BG) photoluminescence (PL) to the coexistence of the bandgap emission, dopant emission, and surface-state emission was realized. This tailoring from undoped to doped emission in the case of Cu impurities is helpful to study the Cu related doping in telluride NCs.     

Cd1-xZnxS/SiO2介孔组装体系的光学性质

利用sol\|gel法得到SiO₂介孔固体, 浸泡热分解后获得Zn不同质量分数的Cd_1-xZn_xS/SiO₂介孔组装体. 吸收光谱表明, 随着x的增加, 吸收边向短波方向移动, 这是由于Zn离子进入CdS取代了Cd离子, 使Cd_1-xZn_xS能隙增大所致. 由于量子尺寸效应, 荧光光谱中发光峰的宽化现象较明显,  同时发光强度随x增大而增强, 这是由于Zn离子使α相比例减少而有利于发光所致.       

硅纳米晶的制备及影响其光致发光因素研究

经过大量的实验得出硅纳米晶(Si-nc)的发光波长位置在750nm附近,从而验证了Si-nc的制备成功.其次,研究了在Si-nc的制备过程中制备不同的多层结构,掺杂不同的稀土元素,是否钝化等方法对材料进行处理后的Si-nc的光致发光强度,其实验结果表明多层结构对Si-nc的发光强度有一定的影响,掺杂不同的稀土元素后Si-nc的发光强度不同,且猝灭效应会降低Si-nc的发光强度,而钝化方法可提高Si-nc的发光强度.     

Sol-Gel Preparation of TiO2/SiO2 Nanocomposites and Their Application in Self- cleaning Textiles

The present study involves the preparation of TiO2/SiO2 nanocrystals and their application in self-clcaning wool-polyester fabrics. The TiO2/SiO2 nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique. The as-prepared nanoeomposites and the nanocomposites coated samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully. The photocatalytic activities of TiO2 -coated and TiO2/SiO2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye. Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO2/SiO2 modified sample with respect to that of pure TiO2 modified sample. Our observations indicate that by applying this technique to the fabrics, self-cleaning materials can be designed for practical application.     

K和Ca掺杂对硅酸锂高温吸收CO2性能的影响

以SiO2和Li2CO3,为反应原料,采用高温固相法,在掺杂不同比例的K或Ca元素的条件下合成了一系列可以直接吸收CO2的硅酸锂(Li4SiO4)材料.实验结果表明,掺杂K或Ca元素都可以提高(Li4SiO4)材料对CO2的吸附率,但K和Ca的最佳掺杂量不同.不同元素掺杂对Li4SiO4吸附稳定性的影响也有不同.采用x射线衍射(XRD)初步探讨了不同元素掺杂对Li4SiO4的吸附性能影响原因.     

YVO_4:Eu~(3+),Bi~(3+)纳米荧光粉沉淀合成及发光性质

采用沉淀法合成YVO4:Eu3+,Bi3+纳米晶.研究掺杂不同Bi3+浓度的YVO4:Eu3+纳米荧光粉在不同温度下的性质.分别采用X射线衍射仪、扫描电子显微镜及荧光光谱仪对荧光粉的结构、形貌和发光性能进行测试.结果表明:合成的荧光粉均为四方相YVO4,形貌呈规则的形状.Bi3+掺杂没有改变荧光粉的形貌.特征发射峰来自于Eu3+的5D0→7FJ跃迁,Bi3+掺杂改变了激发谱峰位,而且使得激发带有一定程度的展宽,同时Bi3+对Eu3+有敏化作用,在适量的浓度范围内纳米荧光粉的发光强度增强.     

Ge_2Sb_2Te_5薄膜及其存储特性研究

采用磁控溅射制备了Ge2Sb2Te5相变薄膜.通过XRD以及四探针法研究薄膜在退火过程中的微结构演变以及电导率变化规律.通过电流-电压特性研究了存储器的存储转变机制.     

SiGe合金氧化层中的纳米结构

我们在硅锗合金衬底上采用氧化等制膜方式生成零维和三维的纳米结构样品，用高精度椭偏仪(HPE)、卢瑟福背散射谱仪(RBS)和高分辨率扫描透射电子显微镜(HR-STEM)测量样品的纳米结构。并采用美国威思康新州立大学开发的Rump模拟软件对卢瑟福背散射谱(RBS)中的CHANNEL谱和RANDOM谱分别进行精细结构模拟。计算且测量出纳米氧化层与锗的纳米薄膜结构分布，并且反馈控制加工过程。优化硅锗半导体材料纳米结构样品的加工条件。我们在硅锗合金的氧化层表面中首次发现纳米锗量子点和量子层结构，我们首次提出的生成硅锗纳米结构的优化加工条件的氧化时间和氧化温度的匹配公式和理论模型与实验结果拟合得很好。     

MECHANISM OF NANOSTRUCTURE IN OXIDATION OF Si1-xGex AL-LOYS

我们在硅锗合金衬底上采用氧化等制膜方式生成零维和三维的纳米结构样品,用高精度椭偏仪(HPE)、卢瑟福背散射谱仪(RBS)和高分辨率扫描透射电子显微镜(HR-STEM)测量样品的纳米结构,并采用美国威思康新州立大学开发的Rump模拟软件对卢瑟福背散射谱(RBS)中的CHANNEL谱和RANDOM谱分别进行精细结构模拟,计算且测量出纳米氧化层与锗的纳米薄膜结构分布,并且反馈控制加工过程,优化硅锗半导体材料纳米结构样品的加工条件.我们在硅锗合金的氧化层表面中首次发现纳米锗量子点和量子层结构,我们首次提出的生成硅锗纳米结构的优化加工条件的氧化时间和氧化温度的匹配公式和理论模型与实验结果拟合得很好.     

化学腐蚀法制备发光硅纳米颗粒

用硝酸和氢氟酸的混合酸液腐蚀普通硅粉,经过超声空化作用,分别在去离子水、无水乙醇中制备出硅纳米晶颗粒.硅纳米颗粒的平均粒径约为2 nm,它们或单独存在,或包裹于非晶态物质中.在320 nm的光激发下,硅纳米颗粒的悬浮液在390 nm处呈现一明显的紫外发光峰,理论分析证明该发光峰与硅量子点的量子限制效应有关.     

SiO_2-YAG:Ce~(3+)玻璃荧光体的制备及其白光LED的封装

采用溶胶-凝胶工艺,以正硅酸乙酯(TEOS)和乙烯基三乙氧基硅烷(VTES)为硅源,以VTES中的乙烯基(CHCH2)为有机改性剂,反应过程中掺入YAG:Ce3+荧光粉,制备出有机改性的SiO2-YAG:Ce3+玻璃荧光体.用X射线衍射仪、光致发光激发谱、光致发光谱和傅里叶红外光谱等测试手段对这种玻璃荧光体进行表征.结果表明:玻璃荧光体主相为Y3Al5O12,该荧光体可以很好地被460nm蓝光激发,发射出550nm的黄光.该玻璃荧光体封装蓝光芯片所得的白光LED器件具有良好的显色性、光通量、流明效率和光强分布.研究结果表明,SiO2-YAG:Ce3+玻璃荧光体是一种潜在的白光LED封装用荧光材料.     

钧瓷的窑变与审美品格

钧瓷是中国五大名瓷之一,与汝瓷、官瓷、哥瓷一样属青瓷系列,烧制过程中发生的窑变使之成为一种非同寻常的彩瓷,窑变造成的钧瓷釉面上的图案、色彩与纹理令其呈现出独一的风貌。本文在讨论钧瓷起源、制作工艺的基础上,着重探讨窑变现象及窑变效果的自然天成性、独一无二性、不可控制性与不可预测性所造就的钧瓷独具一格的艺术美质与审美品格。     

空心CdS纳米晶的合成及发光性能研究

以氯化镉和硫化钠为原料,在水相体系中合成CdS纳米晶,通过透射电子显微镜观察发现,在100℃下合成的CdS纳米晶具有空心结构,粒径为20～30nm,且壁厚均匀,约为3～5nm;在70℃下合成的CdS纳米晶为实心结构,粒径约为20nm,存在较严重的团聚现象.紫外-可见吸收光谱表明：空心CdS纳米晶的吸收波长与实心CdS纳米晶相比蓝移136.74nm,这表明其禁带宽度增大0.11eV.光致发光光谱表明：空心CdS纳米晶的表面缺陷态发射较实心CdS纳米晶有所增强,这是其存在内表面的结果.