Au诱导形成有序Si纳米孔阵列及其应用

以自组装聚苯乙烯小球(PS)单层膜为掩膜,利用Au对Si表面的催化氧化作用以及KOH溶液对单晶Si的各向异性腐蚀特性,在Si(100)面上制备了一系列尺寸小于100 nm有序可控的Si纳米孔阵列.扫描电镜(SEM)和原子力显微镜(AFM)等的测试结果显示:当PS小球溶液与甲醇溶液的体积比为9:11时,可形成大面积无缺陷的单层膜;但当体积比过大时,会导致类似双层膜结构的形成;而当体积比过小时,会诱导形成点缺陷和线缺陷.对PS小球及溅射Au处理过的Si晶片进行KOH溶液腐蚀,随着腐蚀时间变长,纳米孔的横向尺寸和深度增大,其形貌由圆形逐渐变为倒金字塔型,当腐蚀时间超过10 min,纳米孔阵列的有序性遭到破坏.采用离子束溅射技术在倒金字塔型纳米孔衬底上获得了有序Ge/Si纳米岛,而在圆形纳米孔衬底上获得了有序Ge/Si纳米环.进一步对有序Ge/Si纳米岛及纳米环的形成机理进行了解释.     

磁控溅射制备横向梯度分布的Mo/Si周期多层膜

 采用磁控溅射方法在Si基板上镀制了横向梯度分布的Mo/Si周期多层膜。以X射线掠入射反射测量了横向梯度多层膜的膜系结构,在基板65 mm长度范围内,多层膜周期从8.21 nm线性减小到6.57 nm,周期梯度为0.03 nm/mm。国家同步辐射实验室反射率计的反射率测试结果表明：该横向梯度分布周期多层膜上不同位置,能反射在13.3~15.9 nm波段范围内不同波长的极紫外光,反射率为60%~65%。     

Mo/Si多层膜在质子辐照下反射率的变化

为了检验应用在极紫外波段空间太阳望远镜上Mo/Si多层膜反射镜在空间辐射环境下反射率的变化情况, 模拟了部分空间太阳望远镜运行轨道的辐射环境, 利用不同能量和剂量的质子对Mo/Si多层膜反射镜进行辐照实验.辐照前后反射率测量结果显示,由于带电粒子的辐照损伤,质子辐照会使Mo/Si多层膜反射镜的反射率降低,且质子能量越低、剂量越大,对多层膜的反射率影响越明显. 当质子能量E=160keV,剂量＝6×10¹¹/mm²时,反射率降低4.1%;能量E=100keV,剂量=6×10¹¹/mm²时, 反射率降低5.7%;能量E=50keV,剂量=8×10¹²/mm²时,反射率降低10.4%. 用原子力显微镜测量辐照后Mo/Si多层膜反射镜的表面粗糙度比辐照前明显增加,致使散射光线能量逐渐增大并最终导致反射率的降低. 关键词： 质子辐照 Mo/Si多层膜反射镜 辐照损伤     

Fabrication and electrical characterization of nanocrystalline ZnO/Si heterojunctions

Nanocrystalline zinc oxide (nc-ZnO) films were prepared by a sol-gel process on p-type single-crystalline Si substrates to fabricate nc-ZnO/p-Si heterojunctions. The structure and morphology of ZnO films on Si substrates, which were analyzed by X-ray diffraction (XRD) spectroscopy and atomic force microscopy (AFM), showed that ZnO films consisted of 50-100 nm polycrystalline nanograins with hexagonal wurtzite structure. The electrical transport properties of the nc-ZnO/p-Si heterojunctions were investigated by temperature-dependent current-voltage (I-V) measurements and room temperature capacitance-voltage measurements. The temperature-dependent I-V characteristics revealed that the forward conduction was determined by multi-step tunneling current, and the activation energy of saturation current was about 0.26 eV. The 1/C²-V plots indicated the junction was abrupt and the junction built-in potential was 1.49 V at room temperature.     

Reduction of interlayer thickness by low-temperature deposition of Mo/Si multilayer mirrors for X-ray reflection

Thin interlayers are essential for high-quality multilayer optics. We present the first investigation of reducing the interlayer thickness of Mo/Si multilayer structures by cooling the substrate with liquid nitrogen during the deposition. The structures were deposited by means of electron beam evaporation. Even after warming up to room temperature prior to analysis, the interlayers that formed upon cryogenic deposition were found to be approximately 60% thinner compared to room temperature deposition. The interlayer thickness reduction at low temperature and its preservation upon warming up are attributed to a lower mobility of adatoms, reduced surface segregation of Si during Mo-on-Si growth, and/or crystallization of Mo.     

13 nm窄带Si/Mo/C多层膜反射镜

基于多层膜准单色覆盖50~1500 eV能谱的多能点发射光谱测量系统可获得聚龙一号装置Z-pinch等离子体X射线源的能谱结构和总能量等信息。考虑装置的条件,在13 nm处的多层膜需要工作在掠入射角60。常规的Mo/Si多层膜尽管反射率最高,但其带宽较大,不能满足多层膜准单色的要求。因此提出将Mo和C共同作为多层膜的吸收层材料与Si组成Si/Mo/C多层膜,可使反射率降低较小而带宽明显减小。采用磁控溅射方法制备了Si/Mo/C多层膜,其掠入射X射线反射测量表面多层膜的结构清晰完整,同步辐射工作条件下反射率测量,得到Si/Mo/C多层膜在13 nm处和掠入射角60时的反射率为56.5%,带宽为0.49 nm（3.7 eV）。     

中心波长为13．9nm的正入射Mo／Si多层膜

用由铜靶激光等离子体光源等组成的反射率计对自行设计的周期厚度为7.14nm的120层Mo/Si多层膜进行极紫外(EUV)波段反射率测量。由于多层膜层数增加所引起的吸收、膜层界面之间的扩散以及镀膜过程中的膜厚控制误差或表面被氧化(污染)等原因,正入射Mo/Si多层膜在13.9nm处的反射率低于理论计算值73.2%,最后用原子力显微镜(AFM)测量其表面粗糙度为σ=0.401nm。     

用不同的Mo靶溅射功率制备Mo/Si多层膜

 用磁控溅射法制备了周期厚度和周期数均相同的Mo/Si多层膜,用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时,Mo/Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo/Si多层膜的软X射线反射率。研究发现,随着Mo靶溅射功率的增大,Mo/Si多层膜的表面粗糙度增加,Mo的特征X射线衍射峰也增强,Mo/Si多层膜的软X射线峰值反射率先增大后减小。     

Brillouin scattering of light by spin waves in ferromagnetic nanorods

We report the investigations of spin wave modes of arrays of Ni and Co nanorods using Brillouin light scattering. We have revealed the significant influence of spin wave modes along the nanorod axis in contrast to infinite magnetic nanowires. Unusual optical properties featuring an inverted Stokes/anti-Stokes asymmetry of the Brillouin scattering spectra have been observed. The spectrum of spin wave modes in the nanorod array has been calculated and compared with the experiment. Experimental observations are explained in terms of a combined numerical–analytical approach taking into account both the low aspect ratio of individual magnetic nanorods and dipolar magnetic coupling between the nanorods in the array. The optical studies of spin-wave modes in nanorod metamaterials with low aspect ratio nanorods have revealed new magnetic and magneto-optical properties compared to continuous magnetic films or infinite magnetic nanowires. Such magnetic artificial materials are important class of active metamaterials needed for prospective data storage and signal processing applications.     

Fabrication of single-crystalline insulator/Si/insulator double-barrier nanostructure using cooperative vapor–solid-phase epitaxy

Single-crystalline double-barrier Gd₂O₃/Si/Gd₂O₃ nanostructures on Si(1 1 1) were prepared using molecular beam epitaxy. Ultra-thin single-crystalline Si buried in a single-crystalline insulator matrix with sharp interfaces was obtained by a novel approach based on an epitaxial encapsulated solid-phase epitaxy. The I–V characteristic of the obtained nanostructures exhibited resonant tunneling at low temperatures.     

Mo/Si软X射线多层膜的界面粗糙度研究

 用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo/Si多层膜系列, 利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo/Si多层膜的新鲜表面近似等同于同一多层膜的内界面,通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加,Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小,多层膜的峰值反射率先增加后减小。     

Periodic cracks and temperature-dependent stress in Mo/Si multilayers on Si substrates

This work examines formation of the peculiar periodic crack patterns observed in the thermally loaded Mo/Si multilayers. Using the substrate curvature measurements, the macroscopic film stress evolution during thermal cycling was investigated. Then high-speed microscopic observation of crack propagation in the annealed Mo/Si multilayers was presented providing experimental evidence of the mechanism underlying formation of the periodic crack patterns. The origin of the peculiar periodic crack patterns was determined. They were observed to form by the slow crack propagation under quasi-static conditions as a result of the interaction between the channelling crack propagation and the advance of the delamination front.     

质子辐照下Mo/Si多层膜反射镜的微观结构状态

利用透射电子显微镜对质子辐照前后空间太阳望远镜Mo/Si多层膜的微观结构进行了表征, 并对其辐照前后反射率的变化进行了测量.研究表明, Mo/Si多层膜经质子辐照后形成了一些缺陷结构,局部区域Mo/Si的周期性遭到破坏, Mo层与Si层的宽度发生了变化,多层膜层与层之间的界面也比辐照前更为粗糙,部分层状结构由于质子辐照发生了明显的扭曲和折断等现象;此外,质子辐照导致了Mo/Si多层膜反射率的下降,这些微观缺陷的形成是光学性能降低的直接诱因. 关键词： 空间太阳望远镜 Mo/Si多层膜 微观结构 反射率     

Mo/Si多层膜小角X射线衍射结构表征

为了实现对Mo/Si多层膜的结构表征,测量了多层膜样品的小角X射线衍射谱。介绍了小角X射线衍射谱的分析方法,包括Bragg峰值拟合法,傅里叶变换法,反射谱拟合法。Bragg峰值拟合法和反射谱拟合法得到多层膜的周期厚度为7.09nm,两种模型的反射谱拟合法得到界面的粗糙度(扩散长度)为0.40～0.41nm(Si在Mo上),0.52～0.70nm(Mo在Si上),前者要比后者小,这与透射电镜法(TEM)得到的结果0.40nm(Si在Mo上),0.6～0.65nm(Mo在Si上)是一致的。通过基于扩散模型的反射谱拟合法得到的折射率剖面也与由高倍率透射电镜(HRTEM)积分得到的灰度值剖面在趋势上是一致的。通过X射线衍射谱和TEM图像对Mo/Si多层膜进行综合表征,得到了多层膜的精细结构信息,这对多层膜制备工艺的优化具有十分重要的意义。     

Fabrication and surface-enhanced Raman scattering (SERS) of Ag/Au bimetallic films on Si substrates

Ag films on Si substrates were fabricated by immersion plating and served as sacrificial materials for preparation of Ag/Au bimetallic films by galvanic replacement reaction. The formation procedure of films on the surface of Si was studied by scanning electron microscopy (SEM), which revealed Ag films with island and dendritic morphologies experienced novel structural evolution process during galvanic replacement reaction, and nanostructures with holes were produced within the resultant Ag/Au bimetallic films. SERS activity both of sacrificial Ag films and resultant Ag/Au bimetallic films was investigated by using crystal violet as an analyte. It has been shown that SERS signals increased with the process of galvanic substitution and reached intensity significantly stronger than that obtained from pure Ag films.     

ICP-AES法测定铝合金中Fe、Si、Mo、Zr、Ti、Y的研究

本文采用ＩＣＰ－ＡＥＳ法测定了铝合金中Ｆｅ、Ｓｉ、Ｍｏ、Ｚｒ、Ｔｉ、Ｙ,并对样品的溶解方法、共存元素间的光谱干扰、内标元素的选择等进行了研究,建立的分析方法简便快速,有较好的精密度和准确度。     

单发实验测量软X射线多层膜反射镜反射特性

 提出了一种单发实验测量软X射线波段多层膜反射镜反射特性的简易方法。实验采用激光等离子体软X射线源作为光源,用平焦场光栅谱仪分光,在光路中引入掠入射镜以消除高级次谱的影响,用软X光CCD记录,在一发激光打靶实验中,测量了设计中心波长为13.9 nm的Mo/Si多层膜反射镜的反射特性。     

Quenching of Si nanocrystal photoluminescence by doping with gold or phosphorous

Si nanocrystals embedded in SiO₂ doped with P and Au at concentrations in the range of 1×10¹⁸-3×10²⁰ cm⁻³ exhibit photoluminescence quenching. Upon increasing the Au concentration, a gradual decrease in nanocrystal photoluminescence intensity is observed. Using a statistical model for luminescence quenching, we derive a typical radius of ∼3 nm for nanocrystals luminescing around 800 nm. Au doping also leads to a luminescence lifetime reduction, which is attributed to energy transfer between adjacent Si nanocrystals, possibly mediated by the presence of Au in the form of ions or nanocrystals. Doping with P at concentrations up to 3×10¹⁹ cm⁻³ leads to a luminescence enhancement, most likely due to passivation of the nanocrystal-SiO₂ interfaces. Upon further P doping the nanocrystal luminescence gradually decreases, with little change in luminescence lifetime.