Fe/MnPd薄膜各向异性和矫顽力的研究

从理论和实验上对Fe/MnPd薄膜的交换偏置效应、各向异性和矫顽力的增加作了系统的研究.研究表明,在FM/AF结构中,FM和AF的交换耦合作用会诱导系统产生高阶各向异性,在Fe/MnPd结构中获得的单轴和立方各向异性的大小同单轴各向异性与铁磁层的厚度成反比关系一样.同时,铁磁层(FM)和反铁磁层(AF)的交换耦合作用诱导而产生的高阶各向异性的存在是使系统矫顽力增加的重要原因. 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）...     

多孔硅膜龟裂过程的显微荧光观察和分析

用Ｏｌｙｍｐｕｓ显微荧光照相系统对多孔硅膜的龟裂过程进行观测，讨论荧光特性和龟裂过程的关系以及龟裂引起的表观荧光横向不均匀性，为研究荧光机理提供了新信息。     

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。     

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。     

多孔硅——一种新形态的硅材料

多孔硅（ｐｏｒｏｕｓ　Ｓｉｌｉｃｏｎ）是指通过对氢氟酸溶液中的晶体硅片进行阳极氧化，在硅衬底上形成的多孔态的硅材料．本文介绍了多孔硅的形成规律和结构形貌，并对其光学性质和形成机制仆行了简要的评介，最后以多孔硅在大规模集成电路中的应用为主讨论了它的技术应用．     

一种模拟多孔硅结构的新方法

以界面电化学反应动力学和离子输运动力学为基础,构造了一种多孔硅形成与结构的动态计算机模拟模型,模型中采用了电势的指数形式来表示化学反应概率。文中给出了与多孔硅的横断面透射电子显微镜(TEM)图谱和高分辨透射电子显微镜(HRTEM)照片十分接近的形貌图示。 关键词：     

多孔硅衬底上溅射沉积SiC:Tb薄膜的光致发光行为

在多孔硅衬底上用射频溅射法沉积了非晶的SiC:Tb薄膜. 对样品在N2中进行了不同温度的退火处理. 用傅里叶红外变换谱分析了样品的结构.用荧光光谱仪测试了样品的光致发光，在紫外、可见光区域观测到了强的发光峰.发现随着衬底加热温度和样品退火温度的变化，发光峰有明显的强度变化和微弱的蓝移现象.分析了产生这种现象的机理，得出了紫外区域的发光峰是由于氧缺乏中心引起的，而可见区的发光是由于Tb离子产生的. 关键词： 碳化硅 光致发光 氧缺乏中心 多孔硅     

Luminescence of porous silicon films with an europium-containing complex

We obtained porous silicon films modified at room temperature by an Eu³⁺-containing polymer complex. The most intense photoluminescence of Eu³⁺ implanted in the porous silicon was observed at the wavelengths of 611, 618, 691, and 704 nm. In this case, the intensity of the intrinsic photoluminescence of strongly irradiated specimens of porous silicon decreased, while the intensity of weakly emitting films multiply increased. An investigation of the photoexcitation spectra made it possible to establish the effect of Eu³⁺-containing complexes on the mechanism underlying the excitation of photoluminescence of porous silicon. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 499–501, July–August, 1997.     

SERS-active substrates based on n-type porous silicon

Porous silicon (PS) prepared from n-type Si crystal is proposed as a new material for the fabrication of sensitive substrates for surface-enhanced Raman scattering (SERS). The formation procedure for nanostructured silver films on the surface of PS was optimized. Maximum of SERS enhancement for rhodamine 6G probing molecule is observed for samples obtained by the immersion plating from the water solution of AgNO₃ with the 10 mM concentration during 5 min. The dependence of morphological parameters of PS and corresponding silvered surfaces on the anodization current density has been studied. It is shown that the most SERS activities possess substrates produced from PS with lower porosity. The optimum of the PS layer thickness for high Raman signal is about 5 μm. The detection limit for rhodamine 6G adsorbed on Ag-coated PS from the 100 pM solution is established to be comparable with that for p-type PS-based substrates. Thus, the n-type porous silicon is suitable material for the preparation of sensitive SERS-active substrates.     

Study on structural properties of epitaxial silicon films on annealed double layer porous silicon

In this paper, epitaxial silicon films were grown on annealed double layer porous silicon by LPCVD. The evolvement of the double layer porous silicon before and after thermal annealing was investigated by scanning electron microscope. X-ray diffraction and Raman spectroscopy were used to investigate the structural properties of the epitaxial silicon thin films grown at different temperature and different pressure. The results show that the surface of the low-porosity layer becomes smooth and there are just few silicon-bridges connecting the porous layer and the substrate wafer. The qualities of the epitaxial silicon thin films become better along with increasing deposition temperature. All of the Raman peaks of silicon films with different deposition pressure are situated at 521 cm⁻¹ under the deposition temperature of 1100 °C, and the Raman intensity of the silicon film deposited at 100 Pa is much closer to that of the monocrystalline silicon wafer. The epitaxial silicon films are all (4 0 0)-oriented and (4 0 0) peak of silicon film deposited at 100 Pa is more symmetric.     

Physical properties of ZnSe thin films deposited on glass and silicon substrates

ZnSe thin films were deposited onto Corning glass and silicon substrates using thermal evaporation. The samples were prepared at different substrate temperatures. The thin films’ surface chemical composition was determined through Auger electron spectroscopy (AES). AES signals corresponding to Zn and Se were only detected in AES spectra. The samples’ crystallographic structure was studied through X-ray diffraction. The material crystallised in the cubic structure with preferential orientation (111). Optical properties of the ZnSe films were studied over two energy ranges via electron energy loss spectroscopy (10–90 eV) and spectral transmittance measurements (0.4–4 eV). In both cases, the spectral variation of the refractive index and the absorption coefficient were determined by fitting the experimental results with well-established theoretical models. Experimental values for the material’s gap were also found, and photoconductivity (PC) measurements were carried out. Transitions between bands, usually labelled Γ^V₈ → Γ^C₆ and Γ^V₇ → Γ^C₆, were found in the optical and PC responses. A wide spectral photoconductive response between 300 and 850 nm was found in the ZnSe/Si samples prepared at 250 °C substrate temperature.     

Iron films deposited on porous alumina substrates

Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 – 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.     

Luminescence of an erbium- and ytterbium-containing complex in porous silicon films

Er³⁺ and Yb³⁺ ions are introduced into porous silicon films, stabilized by oxidation in an oxygen plasma, in the form of a gadolinium oxychloride-based luminophor by means of thermal diffusion. An investigation is made of the luminescence and photoexcitation spectra of samples with Er³⁺ (10 and 30 wt.%), Yb³⁺ (10 wt.%), and Er³, Yb³⁺⁺ (10 wt.% each). It is shown that the intense IR luminescence (1.00 and 1.54 μm) is caused by cross-relaxation effects. The most effective excitation of the luminescence has been observed in the UV absorption band of the porous silicon. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 428–433, May–June, 1999.     

n型有序多孔硅基氧化钨室温气敏性能研究

利用电化学腐蚀方法制备了n型有序多孔硅, 并以此为基底用直流磁控溅射法在其表面溅射不同厚度的氧化钨薄膜. 利用X射线和扫描电子显微镜表征了材料的成分和结构, 结果表明, 多孔硅的孔呈柱形有序分布, 溅射10 min的WO₃薄膜是多晶结构, 比较松散地覆盖在整个多孔硅的表面. 分别测试了多孔硅和多孔硅基氧化钨在室温条件下对二氧化氮的气敏性能, 结果表明, 相对于多孔硅, 多孔硅基氧化钨薄膜对二氧化氮的气敏性能显著提高. 对多孔硅基氧化钨复合结构的气敏机理分析认为, 多孔硅和氧化钨薄膜复合形成的异质结对良好的气敏性能起到主要作用, 氧化钨薄膜表面出现了反型层引起了气敏响应时电阻的异常变化. 关键词： 有序多孔硅 氧化钨薄膜 二氧化氮 室温气敏性能     

Aluminium-induced crystallization of amorphous silicon films deposited by DC magnetron sputtering on glasses

Amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) films were deposited by DC magnetron sputtering technique with argon and hydrogen plasma mixture on Al deposited by thermal evaporation on glass substrates. The a-Si/Al and a-Si:H/Al thin films were annealed at different temperatures ranging from 250 to 550 °C during 4 h in vacuum-sealed bulb. The effects of annealing temperature on optical, structural and morphological properties of as-grown as well as the vacuum-annealed a-Si/Al and a-Si:H/Al thin films are presented in this contribution. The averaged transmittance of a-Si:H/Al film increases upon increasing the annealing temperature. XRD measurements clearly evidence that crystallization is initiated at 450 °C. The number and intensity of diffraction peaks appearing in the diffraction patterns are more important in a-Si:H/Al than that in a-Si/Al layers. Results show that a-Si:H films deposited on Al/glass crystallize above 450 °C and present better crystallization than the a-Si layers. The presence of hydrogen induces an improvement of structural properties of poly-Si prepared by aluminium-induced crystallization (AIC).     

Fano resonance in heavily doped porous silicon

Unexpectedly, the Fano resonance caused by the interference of continuum electron excitations with the longitudinal optical (LO) phonons was observed in random porous Si by Raman scattering. The analysis of the experimental data shows that the electron states trapped at the Si SiO₂ interface dominate in the observed Raman scattering. The gap energy associated with the interface states was determined. Copyright © 2011 John Wiley & Sons, Ltd.