超高真空中使用的高纯过滤金属蒸发源

设计了一种高真空使用的低电渡过渡金属蒸发源,它能产生高纯金属原子束,且具有一;定的寿命。该蒸发源是将过渡金属Ｃｏ,Ｎｉ或Ｃｒ电镀到一个由Ｗ丝弯成的Ｕ形加热器上构成的。装入超高真空中,利用Ｗ丝自身的电阻加热,去气后,可获得数小时的清洁蒸发。实验结果表明,在离蒸发源约５ｃｍ处,其淀积速率最高可达１０ｎｍｍ／ｍｉｎ,总的淀积厚度超过５００ｎｍ,而且Ａｕｇｅｒ分析结果显示,在超６高真空中淀积的上述几种过渡     

以Al2O3为过渡层脉冲激光法制备PZT铁电薄膜

为实现PZT铁电薄膜与半导体衬底的直接集成引入Al2O3为过渡层，首先用真空电子束蒸发法在Si(100)，多昌金刚石（111）衬底上生长约20nm厚的Al2O3过渡层，接着在上述衬底上采用脉冲激光淀积（PLD）法淀积PZT薄膜，衬底温度为350-550℃。X光电子能谱（XPS）测试表明，在高真空下，电子束蒸发Al2O3固态源能获得化学配比接近蒸发源的Al2O3薄膜。X射线衍射（XRD）测试说明，不论衬底是硅还是多晶金刚石，当衬底温度为550℃时，PZT在Al2O3过渡层上呈现（222）取向的焦绿石相结构，当衬底是金刚石时，通过如下工艺：（1）较低温度（350℃）淀积；（2）空气氛围650℃快速退火5min，可以在Al2O3过渡层上获得高度（101）取向的钙钛矿结构的铁电相PZT薄膜，最后AFM测试显示，在硅衬底上，PZT薄膜的表面均方根粗糙度为9.78nm；而在多晶金刚石衬底上，PZT薄膜的表面均方根粗糙度为17.2nm。     

超高真空电子束蒸发钽膜

在生产和科研上常常用溅射法获得钽膜。但溅射钽的淀积速率很低,一般低于0.1μ/分。最近,我们用 H44·500-3型超高真空电子束蒸发机蒸发钽膜,效果较好。其工作情况是:蒸发真空度:5×10~(-7)托,电子束功率:1.5KW,电子枪高压:11000伏,蒸发温度:>3000℃,液态氮耗量:30升/小时,钽膜淀积速率:30～45μ/分。     

制备条件对电致变色氧化镍薄膜特性的影响

在充氧气的真空室内 ,用电子束蒸发NiO粉末颗粒的方法分别以 0 1和 0 8nm/s的淀积速率制备了氧化镍薄膜 ,并在不同的环境中对薄膜进行热处理。研究了薄膜结构和电致变色特性与淀积速率的关系 ,发现以较慢和较快速率淀积的薄膜分别具有NiO晶粒的 (2 0 0 )和 (111)不同择优取向 ,前者致色范围较小 ,后者致色范围较大。还研究了热处理对薄膜的结构、动态致色范围、致色效率 ,以及红外光谱特性的影响 ,发现热处理对薄膜的致色效率影响较小 ,然而对动态致色范围的影响很大。     

941nm连续波高功率半导体激光器线阵列

用金属有机化合物气相淀积(MOCVD)技术生长了InGaAs／GaAs／AlGaAs分别限制应变单量子阱激光器材料。利用该材料制成了半导体激光器线阵列,连续波工作条件下的中心激射波长为940．5nm,输出功率高达37．7W(45A、2．0V),斜率效率可达0．99W／A(外微分量子效率为75％),最高转换效率超过45％,阈值电流密度为117A／cm^2,该波长的半导体激光器是Yb：YAG固体激光器的理想泵浦源。     

电子束蒸发法制备Co／Cu多层膜中巨磁电阻效应的研究

研究了超高真空电子束蒸发法制备的Ｃｏ／Ｃｕ多层膜中过渡层Ｃｒ、磁性金属Ｃｏ怪和非磁性金属Ｃｕ层厚度等对巨磁电阻效应的影响。     

双生长室超高真空化学气相淀积系统的研制

本文介绍了中国科学院半导体研究所的双生长室超高真空化学气相淀积系统的工作原理、技术参数、结构、性能及特点。该系统具有双生长室、引入准分子激光和多态源等主要优点,是IV族半导体材料生长和研究的强有力工具。     

薄膜制备用电子束蒸发强流气固两用离子源

介绍了一种新型的电子束蒸发（EBE）强流气、固两用离子源，其基本原理是将电子束蒸发技术引人离子源放电室内，使材料的蒸发和游离在同一放电室内完成。该源不仅能引出包括各种难熔材料在内的强流金属和非金属离子束，而且能同时引出气态和固态元素的混合离子束。迄今为止，已引出包括C，W，Ta，Mo，Cr，Ti，B，Cu，Ni，Al，Ar，N以及C和N，Ti等的混合离子束。用于薄膜制备的引出束径为3．6cm，其最大引出束流可达到90mA。利用此源引出的离子束流可在膜基间形成具有良好共混的过渡层，其沉积速率Mo约为2．5nm／s，C可达到8nm／s。     

Mo/α-Al_2O_3界面的二次离子质谱研究

采用电子束蒸发方法，在200℃的抛光（1102）取向的蓝宝石（α－Al2O3）单晶衬底上淀积厚度为300nm的Mo膜。经870℃下不同真空退火时间处理后，运用MCs＋－SIMS技术进行了深度剖析，并结合XRD物相分析，对Mo／A2O3界面问题进行了探讨。结果表明，在Mo／Al2O3界面处存在原子相互扩散形成的过渡层。退火处理后，过渡层展宽，有MoO2生成。延长退火时间，过渡层变化不大。     

Ag-MgF2金属陶瓷薄膜的制备及其微观结构研究

用真空双蒸发源交替蒸发法和单蒸发源混合瞬时蒸发法制备了Ag-MgF2金属陶瓷薄膜。透射电镜、电子衍射、X射线衍射以及X射线光电子能谱分析结果表明，薄膜由晶态超微粒Ag镶嵌于主要为非晶态的MgF2中构成。Ag-MgF2形成的金属陶瓷复合晶体结构所对应的主要谱峰为d=0．26102，0．23540，0．20393nm。用真空单蒸发源混合瞬时蒸发法制备的Ag-MgF2薄膜表面元素的结合能大于双蒸发源交替蒸发法制备的薄膜表面元素的结合能。     

The influence of O2, H2, H2O,N2, CO and CH4 on the structure of thin silver films investigated by ultrahigh vacuum internal stress measurements

It has been demonstrated earlier that the structure of thin metal films can be investigated continuously during deposition by measuring the internal film stress. With these experiments it has been shown that various deposition parameters (evaporation rate, ambient atmosphere etc.) considerably influence the internal stress and thus the structure of the evaporated metal films. In order to separate the various parameters determining film growth we developed an ultrahigh vacuum version of the stress measuring apparatus used previously. An application of this method to silver films deposited onto fresh MgF₂ substrate films in various gas ambients is described. The film structure deduced from the stress curves on the basis of a model for the origin of the internal stress is compared with the structure visible in the electron microscope.     

Microstructural changes in vapour-deposited silver, copper and gold films investigated by internal stress measurements

Structural changes in silver, copper and gold films 100 nm thick evaporated under ultrahigh vacuum conditions were studied by internal stress measurements and by transmission electron microscopy. Tensile stress changes which are not completed until after 5 h for silver and copper and 20 h for gold indicate an increase in the average grain size in these films. The rate of this recrystallization of the film is reduced to about half of its original value when the metal films are coated with a protective layer of MgF₂ immediately after the metal evaporation. When the film recrystallization is not allowed to proceed to completion under vacuum conditions it is again accelerated during exposure of the films to the laboratory atmosphere. From these experiments it can be concluded that the structure of these three metal films as observed using the electron microscope changes from that present at the end of the metal evaporation owing to significant recrystallization. An MgF₂ protective layer can only slow down this recrystallization, not prevent it.     

Search for a wetting layer in thin film growth of para-hexaphenyl on KCl(001)

The non-existence of a strongly bound wetting layer for the system para-hexaphenyl (6P)-KCl(001) was verified by thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). The 6P films were grown by physical vapour deposition under ultrahigh vacuum conditions at 400 K. TDS showed just a single desorption peak even down to a coverage of 0.1 nm mean film thickness. The heat of evaporation for 6P was determined to 2.3 eV. From the change of the XPS K2p substrate signal as a function of the mean film thickness one can conclude that a strong de-wetting exists at the very beginning of the 6P layer growth at 400 K. Additional investigations with atomic force microscopy reveal that at this initial stage the film grows in a form of needle like islands with a high aspect ratio and subsequently terraced mounds of 6P are formed. No dissociation of 6P on KCl was observed.     

Composite nanowire-based probes for magnetic resonance force microscopy

We present a nanowire-based methodology for the fabrication of ultrahigh sensitivity and resolution probes for atomic resolution magnetic resonance force microscopy (MRFM). The fabrication technique combines electrochemical deposition of multifunctional metals into nanoporous polycarbonate membranes and chemically selective electroless deposition of optical nanoreflector onto the nanowire. The completed composite nanowire structure contains all the required elements for an ultrahigh sensitivity and resolution MRFM sensor with (a) a magnetic nanowire segment providing atomic resolution magnetic field imaging gradients as well as large force gradients for high sensitivity, (b) a noble metal enhanced nanowire segment providing efficient scattering cross-section from a sub-wavelength source for optical readout of nanowire vibration, and (c) a nonmagnetic/nonplasmonic nanowire segment providing the cantilever structure for mechanical detection of magnetic resonance.     

Structure and scattering properties of Ni80Nb20-MgO water-window multilayer mirrors

Ni80Nb20-MgO multilayers with d spacing that varies from 2.50 to 3.07 nm were prepared by pulsed laser deposition under conditions of ultrahigh vacuum (UHV) and argon. The morphological and atomic structure in the multilayers was determined by hard-x-ray scattering. It was found that the interface roughness in both cases, UHV and argon deposition, is <0.4 nm, whereas the lateral and longitudinal correlation lengths in the case of argon deposition, 5.0 and 1.0 nm, respectively, are an order of magnitude lower. This is due to a reduction in kinetic energy of the condensing species in argon by orders of magnitude due to multiple collisions, which reduces the lateral relaxation probability. Hence the soft-x-ray reflectance of [Ni80Nb20-MgO]10 multilayers deposited in argon was determined at 413 eV (3.00 nm), middle of the water window. The reflectance has a peak at approximately 35.2 degrees with a half-width of 3.5 degrees and 0.19% maximum value. These results agree well with the simulation results performed by use of the structural parameters obtained from hard-x-ray scattering. The atomic structure determined by high-angle x-ray diffraction shows that both Ni80Nb20 and MgO are amorphous in the as-deposited condition.     

Carbon/Titanium multilayers as soft-x-ray mirrors for the water window

C/Ti multilayers with a period thickness of 2.1-2.7 nm were produced by electron-beam evaporation in ultrahigh vacuum as soft-x-ray mirrors in the water window (lambda = 2.3-4.4 nm). For smoothing the individual interfaces and thus enhancing the total reflectance, each layer was ion polished with an Ar(+) ion beam after deposition. For a multilayer of 85 bilayers, a reflectance of approximately 11% at an angle of incidence of 59 degrees (with respect to the surface normal) by use of s-polarized radiation at a wavelength of 2.77 nm was achieved.     

Nickel nanoparticles and nanowires obtained by scanning probe lithography using point indentation technique

A lithographic method of obtaining metal nanowires and nanoparticles on solid substrates is proposed, which employs a polymer mask with windows for the metal deposition formed by indentation in an atomic force microscope. Using this method, Ni nanowires with a minimum width of 60 nm, thicknesses within 6?C20 nm, and lengths up to 20 ??m and Ni nanoparticles with a preset ordered arrangement have been obtained on a SiO₂ surface. The domain structure in obtained nanoobjects has been studied by the magnetic force microscopy technique.     

Diamond-like Carbon Film from Camphor Soot

Diamond-like carbon film (DLC) has been deposited from the soot of camphor, a natural source, by a simple vacuum deposition technique, for the first time. This method of deposition is simple, convenient and much faster than the conventional gas cracking technique usually adopted for the DLC film deposition. DLC thin film is characterized by Raman, FTIR, solid state ¹³C NMR, ESR and SEM. Preliminary results (XRD and SEM analyses) suggest that the polycrystalline diamond film may also be obtained from this source. The prime novelty of this work is that from the same source, we have been able to synthesize both DLC film as well as polycrystalline diamond film by a simple vacuum deposition technique without using any external gas like the conventional chemical vapour deposition (CVD) methods.     

Preparation of silica thin films by novel wet process and study of their optical properties

Silicon dioxide (SiO2) thin films have gained considerable attention because of their various industrial applications. For example, SiO2 thin films are used in superhydrophilic self-cleaning surface glass, UV protection films, anti-reflection coatings, and insulating materials. Recently, many processes such as vacuum evaporation, sputtering, chemical vapor deposition, and spin coating have been widely applied to prepare thin films of functionally graded materials. However, these processes suffer from several engineering problems. For example, a special apparatus is required for the deposition of films, and conventional wet processes are not suitable for coating the surfaces of substrates with a large surface area and complex morphology. In this study, we investigated the film morphology and optical properties of SiO2 films prepared by a novel technique, namely, liquid phase deposition (LPD). Images of the SiO2 films were obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to study the surface morphology of these films: these images indicate that films deposited with different reaction times were uniform and dense and were composed of pure silica. Optical properties such as refractive index and transmittance were estimated by UV-vis spectroscopy and ellipsometry. SiO2 films with porous structures at the nanometer scale (100-250 nm) were successfully produced by LPD. The deposited film had excellent transmittance in the visible wavelength region.     

Post-nucleation phenomena in the Volmer-Weber mode of epitaxy

Two commonly used methods of depositing a thin film in vacuum are evaporation and sputtering. Evaporation has the advantage of rapid deposition in relatively high vacuum for non-refractory materials. Evaporated films are, however, liable to be weakly bonded to the substrate, because of the low arrival energy of the evaporant, unless effects such as chemical bonding occur. Sputtered films generally bond strongly but sputtering is a much slower deposition process than evaporation so that there may be a high density of contaminating inclusions. As charging also affects the sputtering process special techniques such as r.f. sputtering must be employed for insulating targets.A saddle-field ion source has been developed which operates with cold cathodes and without a magnetic field at pressures compatible with evaporation. Evaporated films deposited in the presence of a beam from this source exhibit the bonding properties of sputtered films. The beam contains a high proportion of energetic neutrals so that the method can be applied to both insulating and conducting substrates. The ion source is compact and can be installed generally in existing vacuum equipment. The source geometry can be varied to ensure that the area covered by the beam matches the deposition area.