多孔硅制备条件对其电致发光特性的影响

应用蒸镀-阳极氧化法制备结构为ITO/PS/p-S i/A l的多孔硅电致发光器件,在7.5V电压下实现了数小时连续电致发光.实验表明,多孔硅电致发光峰位会随着阳极氧化电流密度的增大、腐蚀时间的延长以及HF酸浓度的降低而蓝移.欲制备工作电压较低、发光时间较长、发光效率较高的电致发光样品,则多孔硅制备时的阳极氧化应使用较低电流密度和较短的腐蚀时间.     

多孔硅于甲酸-甲酸钠溶液阳极偏压下的电致发光研究

用荧光分光光度法现场监测了多孔硅于甲酸-甲酸钠溶液阳极偏压下的电致发光行为。发现该体系的电致发光峰值随着阳极偏压增大而发生蓝移;发光峰能量值与阳极偏压呈良好的线性关系,其斜率与多孔硅在阴极偏压下电致发光的结果一致。扫描探针技术研究表明：多孔硅的表面形貌明显地影响其发光性质。提出了多孔硅在甲酸-甲酸钠溶液中阳极偏压下的电致发光与多孔硅表面的Si-H键的氧化作用有关的发光机理。发现了多孔硅于甲酸-甲酸钠溶液中在阳极偏压下电压调制的可见光发射行为,并用量子限制效应对该现象进行了解释。     

多孔硅表面性质导致电致发光的进一步论证

用荧光分光光度法现场监测多孔硅在阳极偏压下于溶液中的电致发光行为 ,该电致发光行为主要取决于多孔硅本身的表面性质 .将电致发光实验后的多孔硅样品再次电解 ,并再次进行电致发光实验 ,发现其发光性能明显改善 ;实验表明 ,多孔硅在阳极偏压下的液相电致发光机制是由表面的Si_H键氧化向导带注入电子 ,并与阳极偏压注入的价带空穴进行复合而发光 ;此外 ,还发现了多孔硅于溶液中在阳极偏压下电压调制的可见光发射行为 ,并以量子限制效应对该现象进行了解释     

硅在HF溶液中阳极溶解的研究

Uhlir及Turner早在50年代就已发现^[1,2],硅在HF溶液中阳极极化时,阳极电流大于某一特定值硅表面会发生电抛光反应,而低于这个值硅表面则会形成一层不同颜色的多孔硅层.1990年Canham发现多孔硅层在室温下有光致发光现象^[3],受到科学界的高度重视,在世界范围内掀起了研究多孔硅的热潮^[4].众多的研究表明,多孔硅的发光性能与其微孔的多少、大小和分布密切相关.但多孔硅要发展成为可实用的光电子材料,首先必须制备出微孔分布均匀,孔径及孔深可控的多孔硅材料.这就有必要弄清多孔硅的形成机理^[5],了解硅在HF溶液中的溶解过程及机理.为此,本文对不同掺杂浓度不同导电类型的(111)晶面单晶硅在HF溶液中的电流-电压(I-V)、电容-电压(C-V)特性进行了研究,并对这些特性进行了分析.     

多孔与平面硅电极界面的电化学行为

研究了重掺杂n-型单晶硅(CSi)在氢氟酸体系中生成多孔硅(PSi)的电化学行为,根据线性极化曲线,选取不同的电流密度,采用恒电流阳极极化法,制备了一系列多孔硅层。利用扫描电子显微镜对其进行了表面和断面形貌的表征,通过线性扫描极化技术和计时电位法,比较了单晶硅电极和多孔硅电极的电化学行为,分析了多孔硅形成前后的塔菲尔曲线和计时电位曲线,给出了多孔硅形成过程中的重要电化学参数,如腐蚀电流、开路电位、塔菲尔斜率等。并对其进行深入分析,根据实验结果,提出了单晶硅电极/电解质界面和多孔硅电极/电解质界面的结构模型,并利用该模型讨论了两种电极界面的电化学特性。     

鲁米诺在铂电极上阳极电致化学发光的机理研究

研究了碱性鲁米诺溶液在多晶铂电极上的阳极电致化学发光(ECL)行为,观察到电极的预极化处理和溶解氧跟发光峰强度和峰形有直接关系。结合XPS谱图和Pt,Pt|S~a~d~s修饰电极的循环伏安特性,给出了鲁米诺阳极ECL两个发光通道的可能反应机理:(1)鲁米诺阴离子在表面有新鲜Pt原子的电极上氧化生成鲁米诺自由基,然后迅速与溶液中的氧反应形成0.22V(vs.Ag)处的发光肩峰;(2)电极表面的铂氧化物能加速原子态氧的发生过程,并增大0.60V(vs.Ag)附近ECL主峰的发光强度。     

吸附钌吡啶类配合物染料分子对氧化多孔硅光致发光性质的影响

化学氧化多孔硅经cis-Ru(bpy)~2(CN)~2的乙醇溶液浸泡后,发光峰位红移,强度减弱,激发态寿命缩短。而在trans-Ru(py)~4(CN)~2溶液中浸泡的氧化多孔硅的发光峰位,强度和寿命几乎没有变化。对比两个染料分子的氧化还原电位和光吸收性质得出：与trans-Ru(py)~4(CN)~2相比,cis-Ru(bpy)~2(CN)~2有一个与多孔硅发光能量接近的低能级吸收带,使得多孔硅纳米粒子向该染料分子传递能量成为可能,能量传递的发生引起了发光峰位的红移和激发态寿命的缩短,虽然伴随着发光效率的损耗,但对有目的地选择染料分子来改变多孔硅的发光峰位和获得激发态寿命尽可能小的多孔硅提供了思路,也为深入理解多孔硅的光致发光机制提供了更多的实验事实。     

吸附钌吡啶类配合物染料分子对氧化多孔硅光致 发光性质的影响

化学氧化多孔硅经cis-Ru(bpy)~2(CN)~2的乙醇溶液浸泡后,发光峰位红移,强度减弱,激发态寿命缩短。而在trans-Ru(py)~4(CN)~2溶液中浸泡的氧化多孔硅的发光峰位,强度和寿命几乎没有变化。对比两个染料分子的氧化还原电位和光吸收性质得出：与trans-Ru(py)~4(CN)~2相比,cis-Ru(bpy)~2(CN)~2有一个与多孔硅发光能量接近的低能级吸收带,使得多孔硅纳米粒子向该染料分子传递能量成为可能,能量传递的发生引起了发光峰位的红移和激发态寿命的缩短,虽然伴随着发光效率的损耗,但对有目的地选择染料分子来改变多孔硅的发光峰位和获得激发态寿命尽可能小的多孔硅提供了思路,也为深入理解多孔硅的光致发光机制提供了更多的实验事实。     

多孔硅镶嵌正丁胺/激光染料复合膜的荧光谱

多孔介质染料镶嵌膜有可能是发展固体染料激光器的一种途径[1].由于其所具有的微孔结构和大的比表面积,故使其成为激光染料理想的载体,以形成多孔硅基发光材料[2].　　我们用正丁胺作碳源,采用射频辉光(ＲＦ)放电法制备碳膜.利用正丁胺、Ｒ6Ｇ/聚乙二醇分别作碳源和蒸发源得到一种混合膜,如将其沉积在刚制备的新鲜多孔硅上则得到多孔硅镶嵌复合膜.本文着重研究了镶嵌于多孔硅中的正丁胺/Ｒ6Ｇ的荧光光谱,并考察了多孔硅衬底的改变对多孔硅镶嵌膜发光的影响.1　样品制备　　(1)多孔硅的制备　制备多孔硅(ＰＳ)所用的材料为(100)晶向的ｐ型单…     

恒电位电解法制备光致发光掺钬多孔硅

研究了一种新的多孔硅掺稀土的电化学方法———恒电位电解，以及稀土硝酸盐支持电解质有机溶剂的新电解体系。这一方法和体系的特点是通过采用适当外加电压来控制电解产物，提高掺入的稀土浓度，提高发光强度，同时避免生成导致发光不稳定的产物，提高发光稳定性。优化了阳极氧化制备多孔硅的条件和阴极还原制备掺钬多孔硅的条件（钬化合物浓度、溶剂、离子强度、电解电压、时间），获得光致发光强度高于多孔硅的掺钬多孔硅。对多孔硅和掺钬多孔硅的光致发光机制进行了讨论。     

Characterization of thermal properties of porous silicon film/silicon using photoacoustic technique

We have applied photoacoustic (PA) technique to study the thermal properties of porous silicon (PS) films formed on p-type Si substrates by electrochemical anodic etching. Four PS samples with close thicknesses but greatly different porosities (from 20 to 60%) were examined. From the dependences of the PA signals on the modulation frequency of excitation light measured under a transmission detection configuration (TDC), effective thermal diffusivities for the two-layered PS/Si samples were determined and found to decrease greatly from 0.095 to 0.020 cm² s^-1 as the porosity increased from 20 to 60%. This revised version was published online in August 2006 with corrections to the Cover Date.     

Atomic Force Microscopic Studies of Light-Emitting Porous Silicon

The surface morphologies of porous silicon (PS), fabricated under various anodic etching conditions and on different typvs of silicon substrates, were studied using atomic force microscopy (AFM). The typical sizes of silicon crystallites of PS were found to be 4-10 nanome-ters,an expected for quantum confinement effect. The results suggested the doping concentration of silicon substrate plays an important role compared with the doping type in determining the surface microstructures. On p^- PS samples, a step-like dependence of the PS crystallite size of HF etching concentration was observed for the first time,in nice agreement with the,tep-like photo-luminescence (PL) phenomenon. which strongly supported the quantum confinement model.     

Er3+、In3+等金属离子对多孔硅光致发光性质的影响

用阳极腐蚀的方法制备了多孔硅样品,用电化学方法在多孔硅中注入Er3+、In3+等金属离子,并对注入离子后多孔硅的光致荧光光谱进行了研究,结果表明：注入Er3+及In3+后的多孔硅在588nm处的发光峰强度大大增加,同时发光峰稍有展宽。随着离子注入时间的增长,强度继续增加,但当离子溶液浓度一定时,这种增强对时间具有饱和性。     

Practical approach for macroporous structure embedded microfluidic system and the catalytic microchemical application

We present a low cost and practical approach to integrate 3D ordered macroporous polyfluoropolyether (PFPE) patterns into a microchannel by a series of porous pattern fabrication processes and subsequent photolithography in a site- and shape-selective manner. The 3D ordered macroporous patterns with high-resolution edges were firstly fabricated by microtransfer molding (μ-TM) of the sacrificial polystyrene (PS) template infiltrated with PFPE as a non-adhesive and solvent-resistant skeletal material. The resulting robust PFPE porous structures with high solvent resistance on a silicon wafer can easily be embedded into the microchannel with the aid of conventional photolithography, leading to a microfluidic system with a built-in microstructure. Moreover, catalytic Pd nanoparticles implanted on the surface of the porous structure were obtained by use of Pd nanoparticle deposited PS spheres, the porous structure embedded channel was utilized to perform a Suzuki coupling reaction.     

Effect of Monocarboxylic Acids on Synthesis of Porous Silicon

Electrochemical formation of deep layers of porous silicon (PS) in monocrystalline silicon of type KEF-20 in electrolytes containing formic and acetic acids is studied. It is found that the chemisorption of carboxylic acids affects electrochemical parameters of the PS formation and the microstructure of its layers. It is shown that the chemisorption and the surface-active properties of acetic acid make the microstructure of porous layers more ordered.     

Polystyrene-based blend nanorods with gradient composition distribution

The polystyrene-based polymer blends, partially miscible poly(bisphenol A carbonate)/polystyrene (PC/PS) and completely miscible poly(2,6-dimethylphenylene oxide)/polystyrene (PPO/PS), in nanorods with gradient composition distribution were discussed. The polymer blend nanorods were prepared by infiltrating the polymer blends into nanopores of anodic aluminum oxide (AAO) templates via capillary action. Their morphology was investigated by micro-Fourier transform infrared spectroscopy (micro-FTIR) and nano-thermal analysis (nano-TA) with spatial resolution. The composition gradient of polymer blends in the nanopores is governed by the difference of viscosity and miscibility between the two polymers in the blends and the pore diameter. The capillary wetting of porous AAO templates by polymer blends offers a unique method to fabricate functional nanostructured materials with gradient composition distribution for the potential application to nanodevices.     

纳米晶状磷酸钙盐/Al2O3-Ti生物复合材料的制备与结构表征

0引言众所周知,钛及其合金具有优良的机械力学性能,但其生物活性不足。因此,在金属基体上涂敷一层生物活性涂层,结合金属与生物活性材料的各自优势,已成为世界各国学者研究最为活跃的生物复合材料体系之一。该体系可用于临床医学,作为人体硬组织等的修复替换材料。目前,已开发出多种在金属基体上制备生物活性涂层的工艺和方法。如:等离子沉积法[1]、离子束溅射法[2]、激光熔覆法[3]、溶胶鄄凝胶法[4]、电化学沉积与水热处理合成法[5]、电泳沉积[6]、电结晶[7]等多种方法。但现有涂层材料尚存在一些问题:(1)由于替换材料的高硬度而导致其周围硬组织坏死[8];(2)由于疲劳磨损或热膨胀不匹配引起涂层脱落[9];(3)由于异质相导致生物活性降解[10]。因此,研究新的制备工艺,开发新的生物复合材料体系就显得十分重要。考虑到Al2O3具有优异的抗磨损、耐腐蚀等性能,以及较好的生物相容性,常作为临床选用的人造硬组织承载材料[11],故在本研究工作中,我们首次采用阳极氧化与水热处理复合工艺研制酸式磷酸钙/Al2O3鄄Ti生物复合材料体系。该体系不同于由日本Ishizawa等研制的HAp/TiO2鄄Ti复合体系[12]。主要体现在两...     

In situ functionalization of porous silicon during the electrochemical formation process in ethanoic hydrofluoric acid solution

In this work, the results of a new method for the preparation of porous silicon (PS) layers with in situ simultaneous functionalization with organic molecules are reported. The molecules of interest are dissolved in the HF ethanoic solution used to prepare the PS layers by partial anodic dissolution of a Si electrode. The method has been proved to be effective with various molecules. In this Communication, the case of PS functionalization with heptyne molecules, studied by FTIR spectroscopy, is reported in detail. The results demonstrate that this new functionalization method, accompanied by a low-level oxidation, is simple, fast, and effective and that it can allow the confinement of the adsorbed molecules selectively in a single layer of a PS stack.     

阳极氧化与超临界干燥结合制备多孔硅

多孔硅（PS）在室温下发射强可见光，这一发现在国际上引起极大关注，成为材料科学、半导体物理和化学以及信息科学领域研究的热点［1，2］．最近三、四年，国内外对PS制备工艺、影响PS发光的因素、PS发光机制、PS应用前景等方面进行了广泛的研究［2］，但有一些基本问题仍待解决，如关于PS发光机制尚存在分歧；PS电致发光效率低，离应用差距甚远；高多孔度PS微孔结构不稳定等．PS微孔内溶剂蒸发过程中，由于毛细管张力的存在，造成微孔骨架受力不匀．强的应力使PS骨架脆弱，甚至微孔结构坍缩，从而导致PS结构不稳定．对于高多孔度…     

A novel tailored bimodal porous silica with well-defined inverse opal microstructure and super-microporous lamellar nanostructure

A novel tailored bimodal porous silica with well-defined inverse opal microstructure and super-microporous lamellar nanostructure has been successfully synthesized by simultaneous application of three-dimensional order polystyrene (PS) beads and an amphiphilic ionic liquid (AIL) as templates.