The room temperature oxidation of porous silicon

The room temperature oxidation of porous silicon was studied using isothermal methods. The oxidation was found to depend on the type of the porous silicon. The microcalorimetric signals from the oxidation of the p⁺- and n-type porous silicon in dry air were different. In humid air the signals from the oxidation could not be distinguished from the strong signal due to adsorption of water vapour, but when the samples were placed in water similar differences were observed. The reason for differences in reactions is discussed. The oxidation in different liquids was also studied. The signal from reactions in methanol and ethanol were found to be 100 times higher than in water. In FTIR studies the reaction gas produced by reactions between alcohols and the porous silicon, silane (SiH₄) was found in the gas. Traces of SiOCH₃ and SiOC₂H₅ groups were also found in FTIR spectra indicating Si---O---C_xH_y passivation of the surface.     

纳米Si-SiOx和Si-SiNx复合薄膜的低温制备及其发光特性

用等离子体增强化学气相沉积法在低温（低于50℃）衬底上沉积Si-SiOx和Si-SiNx复合薄膜,可得到平均颗粒尺寸小至3nm的高密度（最高可达4.0×1012cm-2）纳米硅复合薄膜.500℃快速退火后,这种复 合薄膜显现出优异的可见光全波段光致发光特性.通过比较相同条件下所制备的纳米Si-SiOx和Si-SiNx复合薄膜的光致发光效率,发现纳米Si-SiNx具有更为优异 的光致发光效率,这一点在可见光短波区表现得尤为显著. 关键词： 等离子体增强化学气相沉积 冷衬底 硅纳米颗粒 光致发光     

Covalently Attached Monolayer of Phthalocyanine on Chemically Modified Silicon Oxide Surface

Highly stable monolayers of 2,9,16,23-tetracarboxyl phthalocyanine on 3-aminopropyl-triethoxysilane (ATS) modified silicon and quartz substrates were prepared by reaction of carboxyl and amine. The monolayers were characterized by UV-Vis spectra and AFM measurements. The results indicated that the ultra-thin films on silicon or quartz were smooth, and the ordered structures were observed in these films.     

All porous silicon microcavities: growth and physics

The spontaneous emission of a material can be controlled by placing it in a micron-sized optical cavity. In this paper we introduce the subject and we discuss the realization, the physics and perspective applications of all porous silicon microcavities. The emission properties of the cavities have been characterized as a function of the temperature, of the excitation power and of the response time. Coupled microcavities are demonstrated. Modeling of the structure have been performed on the basis of a transfer matrix approximation.     

On the morphology of stain-etched porous silicon films

Morphology of stain-etched porous silicon films was investigated by a non-destructive technique, based on reflectance spectrometry: dielectric function profiles were computed by spectral reflectance via a finite difference model, and porosity was deduced by the effective medium approximation. Theoretical calculations were supported by high-resolution electron microscopy observations. The relations among oxidising species concentration in the etching solution, porosity profile and surface reflectance of the films were investigated.     

高炉冶炼过程的混沌性解析

根据Grassberger和Procaccia提出的Kolmogorov熵计算方法，以山东莱芜钢铁集团公司1号 高炉和山西临汾钢铁集团公司6号高炉测得的铁水硅含量时间序列为样本，计算了各自的Kol mogorov熵分别为（01453±00151）nats·h-1^-1和（01553±0014 0）nats·h-1^-1，并估计了两座高炉铁水硅含量可预测的时间尺度分别约为6 88和644h.由Kolmogorov熵均为大于零的有限值，定量地说明了这两座高炉 关键词： 混沌 Kolmogorov熵 高炉冶炼过程 铁水硅含量     

光学声子色散关系对多孔硅喇曼谱的影响

测量了多孔硅的喇曼光谱,观察到谱峰有明显的红移和非对称性展宽效应。用微晶模型对此现象进行了解释:认为谱峰的这种变化不完全是由尺寸的空间限制效应和多孔硅的应变造成的,更主要的是多孔硅的色散关系发生了变化。采用不同的色散关系对谱峰进行了拟合,发现色散关系对喇曼谱的拟合有较大的影响。     

Matrix-free infrared soft laser desorption/ionization

Infrared soft laser desorption/ionization was performed using a 2.94 µm Er : YAG laser and a commercial reflectron time-of-flight mass spectrometer. The instrument was modified so that a 337 nm nitrogen laser could be used concurrently with the IR laser to interrogate samples. Matrix-assisted laser desorption/ionization (MALDI), laser desorption/ionization and desorption/ionization on silicon with UV and IR lasers were compared. Various target materials were tested for IR soft desorption ionization, including stainless steel, aluminum, copper, silicon, porous silicon and polyethylene. Silicon surfaces gave the best performance in terms of signal level and low-mass interference. The internal energy resultant of the desorption/ionization was assessed using the easily fragmented vitamin B₁₂ molecule. IR ionization produced more analyte fragmentation than UV-MALDI analysis. Fragmentation from matrix-free IR desorption from silicon was comparable to that from IR-MALDI. The results are interpreted as soft laser desorption and ionization resulting from the absorption of the IR laser energy by the analyte and associated solvent molecules. Copyright © 2004 John Wiley & Sons, Ltd.