基于平板夹具的电子束蒸发沉积薄膜中的挖坑效应分析

电阻加热具有比较好的加热均匀性,可以认为对于非升华性材料,具有比较理想的平面源发射特性n=1.而电子束加热时,通常n=2～3,甚至可以为6,发射特性参数的范围大,没有取值指导理论或规律,具有很大的小确定性,这对分析薄膜均匀性非常不利于采用细分蒸发源为无数个小的面蒸发源的思想,建立了镀膜材料出现挖坑效应时薄膜厚度均匀性的分析模型.分析结果表明电子束蒸发方法很难获得理想的平而蒸发源,不同程度的挖坑效应将使得n值不同程度地偏离n=1,挖坑效应越明显,n值越大.可以从镀膜机结构设计及薄膜沉积工艺选取两方而着手,降低挖坑效应带来的影响.该研究对认识燕发源材料发射特性的物理含义具有重要意义,对实验工作同样具有指导性意义.     

脉冲真空电弧离子源工艺参数对薄膜厚度分布的影响

薄膜厚度的均匀性是影响沉积方法应用的一个重要的因素，利用脉冲真空电弧离子镀技术在Si基片上沉积山类金刚石薄膜，采用轮廓仪对膜的厚度进行了测量，研究服不同工艺参数对薄膜均匀性的影响。实验结果表明：脉冲离子源阴极和基片的距离，主回路工作电压以及沉积频率对薄膜均匀性有不同程度的影响。根据分析结果，找出最佳工艺参数，通过比较两种离子源的结果表明，离子源结构对其镀膜均匀性有较大的影响。     

挖坑效应对球形夹具下电子束蒸发沉积薄膜厚度均匀性的影响

厚度均匀性是薄膜制备过程中不可忽视的薄膜特性,厚度不均匀会导致薄膜成品率降低.熔融性比较差的镀膜材料在蒸发过程中以直接气化为主,挖坑效应比较明显.此时,在分析薄膜厚度均匀性时,蒸发源发射特性不随时间变化的假设不再合理.细分蒸发源为无数个小的薄板蒸发源,建立了镀膜材料出现挖坑效应时薄膜厚度均匀性的分析模型.结果表明,在所选镀膜机结构参数下,挖坑效应对薄膜厚度均匀性影响明显;但挖坑效应并不总导致薄膜厚度均匀性变差,设计合适的镀膜室结构以及薄膜制备工艺参数,可借助挖坑效应在一定程度上改善薄膜厚度均匀性.采用易于出现挖坑效应的材料作为镀膜材料时,该研究对设计薄膜沉积工艺参数具有指导性意义.     

脉冲电弧沉积类金刚石薄膜的厚度建模

从理论和实验出发,分析脉冲电弧源的放电机理,讨论了脉冲电弧源发散特性,得到影响膜厚空间分布的主要因素,建立膜厚空间分布和主要因素之间的数学模型,结果表明和实验数据吻合.     

电弧离子镀的旋转横向磁场弧源设计

电弧离子镀工艺中电弧蒸发产生的大颗粒污染严重影响了所沉积涂层的性能.为了从源头上解决大颗粒难题,本文提出了一种新的旋转横向磁场的设计思路,通过频率和强度可调且覆盖整个靶面的旋转横向磁场控制弧斑的运动.通过有限元模拟磁场的分布,对旋转横向磁场控制的电弧离子镀弧源进行了优化设计.并根据方案制作了旋转磁场发生装置及其电源,使该弧源的旋转磁场具有多模式可调频调幅的功能,用以改善弧斑的放电形式,提高靶材刻蚀均匀性和靶材利用率,减少靶材大颗粒的发射,用以制备高质量的薄膜以及功能薄膜,以拓展电弧离子镀的应用范围.     

微立方结构基底上生长碳纳米管薄膜的强流脉冲发射特性

采用酞氰铁高温热解方法在具有微立方结构的化学镀镍硅基底上生长了碳纳米管薄膜(Si/Ni-CNTs),并在20GW脉冲功率源系统中采用二极结构对其强流脉冲发射特性进行了研究。研究结果表明,在单脉冲发射条件下,随脉冲电场峰值的增大,Si/Ni-CNTs薄膜的发射电流峰值呈线性增加,当宏观场强达到31.4 V/μm时,发射脉冲电流的峰值可达到14.74kA,对应的发射电流密度1.23kA/cm2,在相同峰值,连续多脉冲情况下,碳纳米管薄膜具有良好的发射可重复性,且发射性能稳定。     

银超微粒子-氧化铯牛导体薄膜的多光子光电发射

我们推导了金属超微粒子-半导休薄膜的多光子光电发射公式。制备了■Ag超微粒子-Cs_2O半导体薄膜,用调Q的Nd:YAG激光源(λ=1.06urn,脉冲宽度为10ns)测量了这种薄膜的多光子光电发射特性。发现它具有对光电发射贡献较大的光吸收系数几和较高的量干效率η_n。     

新型阴极弧电源研制及脉冲增强电子发射(P3e)效应研究

本文研制了新型脉冲阴极弧电源,并实现了脉冲增强电子发射(P3e)以提高真空室内等离子体密度。该电源核心由脉冲发射和维持电流系统构成,由单片机和触摸屏系统协同控制和管理。对P3e电源进行放电特性和脉冲增强电子发射效应进行了研究。结果表明,在相同平均电弧电流条件下,与直流相比,P3e技术能够显著提高工件(基体)脉冲电流与平均电流。在电弧平均电流90 A时,基体脉冲电流由5 A提高到19.6 A,基体平均电流由2.2 A最大提高到4.6 A,表明脉冲增强了电子发射,进而获得高的等离子体密度,这将有助于增加膜层致密性、降低膜层应力。该新型电源对于阴极弧靶中毒抑制、膜层结构改善、膜层颗粒污染控制具有重要的意义。     

大面积矩形电弧蒸发源电磁场的研究

大面积矩形电弧蒸发源合理的设置靶源磁场并有效的控制电弧弧斑的运动是十分重要的。本文基于大量的试验研究对电磁场在靶面各处产生的磁场强度的计算进行了理论推导，建立了数学模型，并进行了比较精确的计算。计算结果与实测值很好的吻合，该计算可作为大面积矩形电弧蒸发源电磁场设计的依据。     

脉冲真空放电离子密度的测量

由于采用脉冲放电沉积技术能够克服连续电弧离子镀沉积时产生的液滴及负偏压放电的缺点，特别是它在镀制类金刚石薄膜中显示出来的独特性能：不含氢和硬度高，使其在薄膜沉积技术中越来越受到广大研究者的重视。为了更深入地研究薄膜的沉积工艺和薄膜性能之间的关系，迫切需要对脉冲真空放电等离子体的微观参数进行深入透彻的研究，如离子密度及其空间分布等。本文介绍了测量脉冲真空电弧离子源离子密度的方法，并采用该方法测量了脉冲真空电弧离子源离子密度及其空间分布，分析和研究了影响离子空间分布的各种参数。     

脉冲真空弧离子源的质谱分析

本文介绍了脉冲真空弧离子源的特点,建立了脉冲真空弧离子源工作瞬间放气成分的质谱分析系统.应用四极质谱仪记录了真空系统中离子源工作前后的谱图,并通过数据软件的二次处理初步取得了脉冲真空弧离子源放电空间的增量成分分析;开展了不同绝缘介质对脉冲真空弧离子源工作瞬间所产生气体成分的对比研究.     

脉冲阴极弧金属等离子体源的调试及其应用

对脉冲阴极弧金属等离子体源的工作参数进行了测量,研究了离子流与磁导管偏压以及磁场电流与离子流之间的关系,确定了其最佳工作参数.并应用该脉冲阴极弧金属等离子体源和等离子体浸没离子注入与沉积技术制备了TiC薄膜.对改性层的显微硬度、摩擦磨损性能和膜基结合力进行了测试分析.结果表明:合成TiC薄膜后,试样的显微硬度、摩擦磨损性能得到了明显的改善,并且膜层与基体之间的临界载荷为36.03 N.     

Diamantartige Kohlenstoffschichten steigern die Effizienz

Diamond‐like carbon thin films enhance efficiency — laser arc deposition of ta‐C Rising prices for fossil fuels as well as the increasing effects of the climate change due to the emission of greenhouse gases reveal the necessity of saving energy. Low friction coatings have an enormous potential in saving energy. Carbon based coatings — named as DLC coatings — are especially well suited for low friction coatings. In particular hydrogen‐free tetrahedral amorphous carbon (ta‐C) coatings are of great interest due to their extraordinary low wear properties. In addition they show excellent low friction properties and especially in combination with specific lubricants the so‐called super low friction effect. For the deposition of ta‐C coatings PVD methods have to be applied instead of CVD methods as it is the case for conventional DLC coatings. We have developed a deposition method which is based on a pulsed arc steered by a laser (Laser‐Arc). This allows us to use large cathodes resulting in a high long‐term stability. Furthermore, the carbon plasma source can be combined with a filtering unit removing almost all droplets and particles, which usually are characteristic for an arc process. The resulting Laser‐Arc source allows for the deposition of smooth and virtually defect‐free ta‐C coatings with a competitive deposition rate.     

Plasma investigation of PVD processes operating in dc continuous and/or dc pulsed mode

The plasma of different dc and dc pulsed pvd processes (TiN and Ta²O⁵ magnetron sputtering, Ta²O⁵ ion plating) has been investigated by means of a mass spectrometric plasma monitoring system PPM421 (Inficon). The ion energy distribution of the process relevant positive ions has been measured and the dependence of the plasma properties on the process parameters like pulse frequency and pulse voltage was analysed. Starting with an overview concerning a theoretical concept behind the plasma properties in dc pulsed sputter processes, theoretical predictions from this theory about the kinetic energy of the ions and the shape of the ion energy distribution are compared with the experimental results in different dc pulsed sputter processes. A significant difference can be seen in level and distribution of the ion energy in conventional dc magnetron processes compared to dc pulsed processes. The process parameters pulse frequency and pulse voltage control the kinetic energy of the process ions. The theoretically predicted properties of a pulsed plasma could experimentally be confirmed.     

Properties of super-hard carbon films deposited by pulsed arc process

The pulsed vacuum arc discharge (pulsed arc) is the most efficient PVD-technology for the deposition of super-hard carbon films on tools and machinery parts. Using the pulsed arc discharge a stable evaporation process of carbon and an efficient deposition of hydrogen-free ta-C type films is possible. In this paper, important properties of such ta-C films and their process conditions are explained. The films were characterized by hardness measurements using nanoindentation, friction and wear properties using oscillating sliding tests, and structural analysis using Raman spectroscopy.     

脉冲偏压幅值对TiN／TiAlN多层薄膜微观结构和性能的影响

采用电弧离子镀的方法,通过改变脉冲偏压幅值在M2高速钢表面制备了TiN／TiAlN多层薄膜,研究了脉冲电压幅值TiN／TiAlN多层薄膜微观结构和性能的变化。随着脉冲偏压幅值的增加,薄膜表面的大颗粒数目明显减少。EDX结果表明,脉冲偏压幅值的增加还引起Al／Ti原子比的降低。TiN／TiAlN多层薄膜主要以（111）晶...     

Spontaneous emission from a planar microcavity below threshold and the wolf effect

Abstract

Equivalence between a planar microcavity below threshold and a partially coherent primary source is pointed out for the first time. Spatial coherence properties of spontaneous emission from the planar microcavity are controllable by varying two cavity parameters of the cavity length and the mirror reflectivity. The spontaneous emission gives rise to the Wolf effect which is spectral changes induced by the spatial coherence. It is clearly shown from our theoretical analyses that the spectrum in the far field shifts toward higher frequencies than that on the emitting plane of the planar microcavity. In particular, the blue shift of the far-field spectrum takes a maximum value at the centre of the far-field plane and decreases gradually far away from the centre. Moreover, the blue shift increases with decreasing values of the two cavity parameters.     

Modulation of field emission properties of znO nanorods during arc discharge

Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.