Anomalous Emission And Carrier Effect of Fresh Porous Silicon

IntroductionThe study of luminescent silicon material[1] ,especially porous silicon( PS) ,has received muchattention owing to its potential application ininformation technology. Many models have beenproposed to explain their photoluminescnece andelectroluminescence[1— 11] . Three of the mostpopular models are the quantum confinement[1,2 ] ,surface trapping[3 ,4] ,and oxygen related chemicalspecies formation[5,6] .It has been suggested thatsurface chemical reaction plays an importantrole info…     

Antibody-Antigen Reactions in Porous Sol-Gel Matrices

Porous silica gels, synthesized via the acid hydrolysis and basic condensation of TMOS, have been used for the encapsulation of antigens. The pores of the matrix are large enough to allow the diffusion of antibodies through the gel. Antigen-antibody specific fixation occurs within the sol-gel matrix. It can be detected via the so-called enzyme linked immunosorbent assays (ELISA). Antigen-antibody associations occurring in the gel are optically detected via the reaction of a peroxidase conjugate with ortho-phenylenediamine leading to the formation of a yellow coloration. Immunoassays have been performed using the hydatid cyst fluid as the source of antigens and sera from human patients as the source of antibodies. Specific fixation appears to be as good in the sol-gel matrix as in antigen solutions.     

Charge Carrier Transport in Disordered Organic Matrices

Various aspects of charge carrier transport in solid disordered matrices are considered. It is shown that the field dependence of mobility is defined by correlation properties of the material, specifically, by the law of spatial decay of the correlation function energy–energy. The well known Poole–Frenkel dependence of mobility is observed in polar materials and is connected with an exceedingly slow decay of the correlation function in dipole glass. The true behavior of mobility in nonpolar materials differs from the Poole–Frenkel dependence but is barely distinguishable from it in a narrow range of fields studied experimentally. The charge transport in media with short-range and charged traps is considered. It is shown that the electrode roughness affects not only the efficiency of injection of charge carriers but their transport characteristics as well.     

多孔硅的XPS研究

对两类孔硅样品测量X射线光电子能谱（XPS）：一类为在空气中放置近一年的多孔硅,另一类为HF处理后的具有新鲜表面的多孔硅。通过分析Si2p和O1a芯能级谱可以得到以下结论：新制备的多孔硅表面只有少量的O和F存在,其中氧是以OH^-形式存在,它的形成与清洗过程中F^-被OH^-取代有关。随着放置时间的增加,表面逐渐被氧化,形成正化学计量比的SiO2,而随着从表层向内的深入,逐渐变为次氧化物。结果表明刚制备的多孔硅与大气中放置氧化后的样品表面态的类型是不一致的。     

多孔硅的电化学制备

单晶硅在氢氟酸溶液中阳极氧化可制得多孔硅, 多孔硅是一种以新形态存在的硅, 与单晶硅相比, 它表现出独特的物理性质和化学活性。荧光光谱峰的蓝移表明, 在p-型低掺杂衬底硅上形成的多孔硅中存在量子尺寸效应, 新近获得的Raman光谱也证实了这一点。     

Voltage-tunable Electroluminescence of Porous Silicon

The voltage-tunable EL was obtained upon cathodic bias of n-type PS in contact with aqueous solution containing the persulphate ion. The EL behavior as a function of the external voltage and time was investigated. The results suggest that the mechanisms of voltage-tunable EL of n-typt PS cannot easily be attributed to quantum confinement effect.     

硅材料在微型燃料电池中的应用*

微型燃料电池被认为可作为便携式电子设备的下一代电源而越来越受到关注。传统的石墨、金属等材料用于微型燃料电池时产生了不少问题,如石墨材料微加工性能差,金属易腐蚀、密度较大等不利于应用于便携式设备。硅材料因为其低的气体透过率、高的导热系数和适于微加工等特性在微型质子交换膜燃料电池中得到了越来越多地应用。本文对硅材料在微型燃料电池的气体扩散层、质子交换膜构造中的应用以及硅材料作为基底制作微型燃料电池技术的进展进行了综述,并对硅材料在微型燃料电池领域应用的技术特点及前景做了分析与讨论。     

掺铕多孔硅的恒电位电解法制备及其光致发光

首次报道掺稀土多孔硅的恒电位电解法和稀土硝酸盐－支持电解质－非乙醇有机溶剂的电解体系,这一新方法和新体系具有易于控制电解产物,可掺入高浓度稀土（１０＾２１／ｃｍ＾３以上）,自主控制掺人稀土的浓度并显著增强多孔硅室温光致发光的优点。研究了溶剂、外加电压、Ｅｕ（ＮＯ３）３浓度及电解时间对多孔硅（ＰＳ）室温光致发光的影响,优化了恒电位电解法制备掺铕多孔硅的条件,获得了室温光致发光强度高于多孔硅的ＰＳ：Ｅ     

Micro Dry Ashing for Trace Selenium Determination in Organic Matrices

Abstract

A specific sample treatment method was established for determination of ng levels of Selenium in microquantities of organic compounds. Our task was determination of Selenium traces, in a new pharmaceutical product, as a result of a laboratory scale synthesis, in an amount of several tens of mg. GFAAS was chosen as an analysis method, due to its sensitivity and rapidity. Among the wet and dry methods for organic material digestion tried, the low temperature dry ashing using ashing aid, was the only one which gave satisfactory recoveries of Selenium. Micro dry ashing was performed, using an Ethanol solution of Magnesium Nitrate on samples spiked with Selenium Nitrate in the range of concentration of 1–6ng mg^?1 at a temperature of 450°C for two hours. The presence of Magnesium Nitrate and the heating suppress the atomization with approximately 15–25%. Recoveries of Selenium varies as a function of the organic matrix: for polyaromate compounds as Chrysene and Fluoranthene they lie between 90–103% and for oxygenated compounds as Dimethoxybenzoic acid or Phthalates 23–50% respectively.

Another aspect of chemical interference by organic matrices and the way how to overcome it, has been clarified.     

发光多孔硅的化学传感特征

发光多孔是一种新型的光电器件材料。其荧光的猝灭或增敏，以及其电学特性的变化可作为化学伟感信息用于电化学传感技术。本文评述了自发光多孔硅首次报道以来在化学传感领域的应用研究进展。     

多孔硅的制备与光伏特性研究

采用特制的电解池在不同条件下制备了一系列多孔硅样品。通过测定其ＳＰＳ发现，多孔硅的ＳＰＳ特征带同单晶硅相比有明显蓝移，并且随制备条件不同，蓝移效应也不同。电解质中ＨＦ浓度和电解时间对基ＳＰＳ响应有明显影响，这一现象的出现主要归因于最子线阵的生成。     

预处理对多孔硅形成过程的影响(英文)

本工作初步探讨了开路电位下对硅片进行预处理时多孔硅的形成过程 .电化学极化实验、扫描电镜和拉曼谱学的研究表明 ,预处理可以加速硅 /溶液界面上的化学或电化学反应 ,从而加快多孔硅的生长过程 ,最终导致光致发光的光谱红移 .多孔硅的厚度随预处理时间的增长而减小     

多孔硅的光电化学特性研究

研究了多孔硅的光电化学特性和溶液中的光致电荷转移机一，由Ｐ型单晶硅制备的多孔硅具有Ｐ型半导体的光电性质，且光电流响应高于单晶硅，由于多孔硅表面态能级对光致电荷的陷阱作用，多孔硅呈现了独特的光电流响应和光致电荷转移性质。     

多孔硅的晶态结构与表征方法*

多孔硅的生成过程涉及从完美硅单晶逐渐变为不完整晶体,甚至无定形结构,其结构变化取决于制备条件和硅基底的掺杂类型与浓度。多数研究者利用不同的非原位手段研究多孔硅生成过程中晶态结构的变化,进一步研究其光致发光性能。本文对不同条件下生成的多孔硅的晶态结构进行了归纳总结,比较了透射电子显微镜、X射线衍射技术及拉曼光谱技术3种表征方法的特点及其对晶态结构认识的影响,指出不同微观表征手段的局限性使得众多的报道结果相差较大。最后本文就该领域的发展态势和急需解决的问题进行了总结。     

多孔硅研究进展

综述多孔硅的形成规律，介绍其各种物理、化学特性和形成机制等，并以多孔硅电致光发射器件的研制为主，讨论它的应用技术。     

Determination of Micro Amounts of Metallic Silver in Silver Salt Matrices

ABSTRACT

A spectrochemical method has been developed for the quantitative determination of metallic silver in silver nitrate and silver chloride or bromide matrices exposed to light. The method is based on the oxidation of silver(0) by iron(III) at pH 3.5 in the presence of ferrozine. The resulting absorbance of the iron ferrozine complex is measured at 562 nm. Less than 0.1 mg of metallic silver can be determined with a relative standard deviation better than 6%.     

Specific Features of Porous Silicon Synthesis in Aqueous-Alcoholic Solutions

The uniformity of growth of porous silicon layers, electrochemical parameters of their synthesis, surface resistance, and morphology of porous structure in aqueous and aqueous-alcoholic electrolytes (H₂O-C _n H_2n+1OH, n = 1, 3-5) was studied.     

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.     

多孔硅成核的电化学研究

将p型单晶硅在HF溶液中进行阳极电化学腐蚀制备出孔隙率约为30%~85%、直径为2~30nm不等的多孔硅,用原子力显微镜(AFM)观察其表面形貌。采用电化学工作站(CHI660A)监测p型硅电极在不同浓度HF溶液中的电流-电压特性,记录恒电流情况下硅电极的电压变化。这些曲线可从精确反映多孔硅形成的早期成核过程。将这些电化学特性曲线在同一坐标轴下显示,得出多孔硅的电化学成核机理。