储存初期多孔硅膜龟裂现象的显微观测与分析

用显微镜观察到多孔硅薄膜在空气中储存初期的龟裂现象，揭示了发光畴区周围裂缝的来源，初步了探讨了龟裂现象的成因。．     

多孔硅激光染料镶嵌膜的荧光光谱研究

本文对以多孔硅为载体，镶嵌激光染料形成复合膜的光致发光进行了研究，比较了镶嵌膜与其他不同状态下染料发光的差异，发现镶嵌染料荧光光谱线型较其他状态下明显趋于对称，同时考察了衬底情况的改变对镶嵌膜发光的影响。通过对实验结果的分析指出，这种硅基镶嵌膜中的染料的发光主要来自单体的荧光发射。     

多孔硅荧光皮秒衰减测量与发光机理分析

荧光光谱、荧光皮秒衰减和红外光谱测量表明,自然氧化多孔硅中有两种不同的发光机理并存,一种是由量子限制效应所决定的,另一种是由氧化引入的发光机理。 关键词：     

多孔硅实验方法

多孔硅实验方法王兰芳，邓家干（陕西工学院汉中７２３００３）（广西农业大学南宁５３０００５）前言多孔硅（ＰｏｒｏｕｓＳｉｌｉｃｏｎＬａｇｅｒ，简称ＰＳＬ）是一种把单晶硅作为材料，通过各种方法使硅表面形成一层由大量垂直于表面的微孔（孔径为１—１００ｎｍ）...     

多孔硅的表面碳膜钝化

报道对多孔硅（ＰＳ）进行碳膜（ＣＦ）钝化处理的结果。红外吸收光谱表明,经钝化处理样品的表面由Ｓｉ－Ｃ、Ｓｉ－Ｎ和Ｓｉ－Ｏ键所覆盖;荧光我谱表明,经钝化处理的样品较未处理的样品发光强度提高４￣４．５倍,且发光峰位明显蓝移;存放实验显示,经钝化处理的样品发光强度稳定、发光峰位不变。这些结果表明正丁胺可以在多孔硅表面形成优良的钝化碳膜,是一种十分有效的多孔硅后处理途径。     

发光多孔硅荧光峰位的钉扎和尺寸量子化

发光多孔硅荧光峰位的钉扎和尺寸量子化自从Ｃａｎｈａｍ［１］在１９９０年发现多孔硅（ＰＳ）在窒温下高效率的可见光发射以来，由于其在光电技术上的应用前景，加上它和硅大规模集成工艺的可容性，很快就引起人们的极大关注。因此，之后不久各国有好多研究组都重复了这...     

金刚石膜/多孔硅复合材料的性能表征

提出了一种新颖的多孔硅表面钝化技术,即采用微波等离子体辅助的化学气相沉积（MPCVD）方法在多孔硅上沉积金刚石薄膜。采用原子力显微镜（AFM）、扫描电子显微镜（SEM）、X射线衍射仪（XRD）、拉曼光 谱仪和荧光分光度计对多孔硅及金刚石膜的表面形貌、结构和发光特性进行了表征。结果表明采用微波等离子体化学气相沉积法可在多孔硅基片上形成均匀、致密、性能稳定且对可见光具有全透性的金刚石膜。金刚石膜与多孔硅的复合,大大稳定了多孔硅的发光波长和强度,同时增强了多孔硅的机械强度。     

矫顽力可调的多孔硅基Fe膜

采用电化学腐蚀法制备了不同多孔度的多孔硅(PS),再通过磁控溅射法在该PS衬底上沉积了一定厚度的Fe膜;并对样品进行了X射线衍射的结构分析、扫描隧道显微技术的表面形貌观察和磁光克尔效应的测量.发现在同一Fe膜厚度下，相对于参考样品硅上的Fe膜，多孔硅上Fe膜的矫顽力更大;同时观察到多孔硅基Fe膜随着PS多孔度的增加，矫顽力相应变大;而对于多孔度相同的多孔硅基样品,随着Fe膜厚度的增加矫顽力却逐步减小.得出了多孔硅特有的海绵状疏松结构能有效调节Fe膜矫顽力大小的结论. 关键词： 多孔硅 海绵状结构 Fe薄膜 矫顽力     

多孔硅的分形结构及其荧光特性

用扫描电子显微镜(SEM)对多孔硅的结构进行了分析.结果显示多孔硅具有分形特性,同计算机模拟结果一致;用荧光光谱仪,研究了多孔硅的荧光特性与激发波长的依赖关系.激发光谱测量结果发现,当激发波长从650 nm变到340 nm时,荧光谱峰位从红端780 nm连续蓝移到500 nm.综合分析说明：正是由于多孔硅的分形微结构以及量子限制效应,导致了多孔硅的荧光特性随激发波长改变的物理现象.     

多孔硅膜微结构的透射电镜研究

用透射电镜观察到由Ｓｉ（ｌｌｌ）衬底生长的多孔硅膜具有双层结构和明显的不均匀微结构，初步探讨了荧光机理与微结构的关系。     

Cathodoluminescence from nanocrystalline silicon films and porous silicon

Received: 4 May 1998 / Accepted: 30 October 1998     

Growth,optical, and electrical properties of silicon films produced by the metal-induced crystallization process

Amorphous Si (a-Si) and Ni films were deposited by electron beam evaporation on to borosilicate glass (BSG) substrate maintained at ambient temperature. The BSG/a-Si/Ni stack was subjected to post deposition annealing in air at various temperatures from 200 to 500 °C for 1 h. Electron diffraction was employed to characterize the crystallographic phases appearing on the stacks that were depending on initial conditions. Clear evidence of the formation of hexagonal Si and fcc NiSi₂ was shown by TEM. In parallel, an increase of refraction index was observed. Electrical resistivity measurements showed that resistance is of the order of kilo ohms in the as-deposited films, increasing sharply to giga ohms in films annealed at T higher than 300 °C. A large band gap of 2.23 eV which is the combined contribution from a-Si, wurtzite-Si, and Ni silicide phases, is observed.     

A reassessment of electron escape depths in silicon and thermally grown silicon dioxide thin films

The escape depths of electrons with kinetic energies of approximately 1150 and 1380 eV in Si and thermally grown SiO₂ thin films have been calculated, using three methods, from X-ray photoelectron spectra of samples which have been characterized by high resolution transmission electron microscopy (HRTEM). The most reliable and reproducible escape depths derived in this study are significantly less than the average of those reported in the literature. It is believed that this is due principally to inaccurate characterization of the samples previously used for escape depths measurements.     

Raman analysis of amorphous silicon ruthenium thin films embedded with nanocrystals

We report the Raman analysis of both as‐deposited and annealed amorphous silicon ruthenium thin films embedded with nanocrystals. In the Raman spectra of as‐deposited films, variations of TO peak indicate a short‐range disorder of a‐Si network with an increase of Ru concentration. The substitutional Ru atoms lower the concentration of Si―Si bonds and suppress the intensity of TO peak, but have less effect on TA, LA and LO peaks. In the Raman spectra of annealed films, characteristic parameters confirm the upgrade of a‐Si network at a low annealing temperature and the emergence of both ruthenium silicide and silicon nanocrystals at 700 °C. Although ruthenium silicide nanocrystals present no Raman peaks in the Raman spectra of as‐deposited samples, the non‐linear variations of intensity ratios I_{LA + LO}/I_TO and I_TA/I_TO still suggest their existence, and these nanocrystals are subsequently verified by high‐resolution transmission electron microscopy. Copyright © 2015 John Wiley & Sons, Ltd.     

XAFS analysis of indium oxynitride thin films grown on silicon substrates

Local structure of indium oxynitride thin films grown on silicon substrates was investigated by X‐ray absorption fine structure technique incorporated with first principle calculations. The thin films were grown by using reactive gas timing radio frequency (RF) magnetron sputtering technique with nitrogen (N₂) and oxygen (O₂) as reactive gasses. The reactive gasses were interchangeably fed into sputtering system at five different time intervals. The gas feeding time intervals of N₂:O₂ are 30 : 0, 30 : 5, 30 : 10, 30 : 20 and 10 : 30 s, respectively. The analysis results can be divided into three main categories. Firstly, the films grown with 30 : 0 and 30 : 5 s gas feeding time intervals are wurtzite structure indium nitride with 25 and 43% oxygen contaminations, respectively. Secondary, the film grown with 10 : 30 s gas feeding time intervals is bixbyite structure indium oxide. Finally, the films are alloying between indium nitride and indium oxide for other growth condition. The fitted radial distribution spectra, the structural parameters and the combination ratios of the alloys are discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Tuning the cathodoluminescence of porous silicon films

We have obtained intense cathodoluminescence (CL) emission from electron beam modified porous silicon films by excitation with electrons with kinetic energies below 2 keV. Two types of CL emissions were observed, a stable one and a non-stable one. The first type is obtained in well-oxidized samples and is characterized by a spectral peak that is red shifted with respect to the photoluminescence (PL) peak. The physically interesting and technologically promising CL is however the CL that correlates closely with the PL. Tuning of this CL emission was achieved by controlling the average size of the nanostructure thus showing that the origin of this CL emission is associated with the quantum confinement and the surface chemistry effects that are known to exist in the porous silicon system. We also found that the electron bombardment causes microscale morphological modifications of the films, but the nanoscale features appear to be unchanged. The structural changes are manifested by the increase in the density of the nanoparticles which explains the significant enhancement of the PL that follows the electron irradiation.     

Numerical and experimental analysis on green laser crystallization of amorphous silicon thin films

The effect of laser fluence on the crystallization of amorphous silicon irradiated by a frequency-doubled Nd:YAG laser is studied both theoretically and experimentally. An effective numerical model is set up to predict the melting threshold and the optimized laser fluence for the crystallization of 200-nm-thick amorphous silicon. The variation of the temperature distribution with time and the melt depth is analyzed. Besides the model, the Raman spectra of thin films treated with different fluences are measured to confirm the phase transition and to determine the optimized fluence. The calculating results accord well with those obtained from the experimental data in this research.     

Analysis of thin thermal silicon nitride films on silicon

We have investigated the chemical and electrical properties of very thin (<32 Å thick) silicon nitride films grown by rapid thermal nitridation of silicon. These films were of interest as a possible means of tailoring the barrier heights of silicon Schottky barrier diodes. Auger and XPS analysis showed that the level of oxygen contamination in the films was very low ([N]/[N]+[O]) =0.85 to 0.95). The oxygen is located primarily at the surface and interface of the films. Metal-nitride-silicon devices were characterized by I-V and C-V techniques. These measurements indicated an increase in barrier heights to p-type substrates and a decrease in barrier heights to n-type substrates compared to values measured in the absence of the nitride layers. The magnitude of the change in barrier height increases with increasing nitride thickness. The barrier height can be varied reproducibly over a wide range. For molybdenum on p-type, this range is greater than half the bandgap. For titanium and molybdenum on p-type diodes, barrier heights higher than 1.0 V can be achieved. These measurements could be explained by a reduction in the density of silicon interface states with increasing nitride thickness or by the presence of positive fixed charge in the nitride layer.     

Atomistic configurations and energetics of crack extension in silicon

We report the first atomistic determination of the minimum energy path for a series of bond ruptures to advance a crack front. Saddle-point configurations on (111) cleavage planes in Si reveal a steplike distribution of atomic displacements, implying a kink mechanism which is known to control dislocation mobility. Manifestations of lattice trapping and directional cleavage anisotropy are further elucidated.