辉光放电气相沉积氮化钛薄膜

本文叙述了辉光放电气相沉积氮化钛薄膜的工艺。它具有物理气相沉积与化学气相沉积的综合特点。在此工艺中,辉光放电作为化学反应和沉积的介质,通过等离子体的激活作用,可在低气压下直流辉光放电的工件(阴极)表面上获得化合物薄膜。已在工艺实验中,工件表面上沉积了致密的氮化钛涂层。此工艺的沉积温度低、沉积速率较高。     

常压辉光放电等离子体制备荧光碳纳米粒子

采用常压辉光放电等离子体制备了超细荧光碳纳米粒子。分别采用聚乙二醇(PEG)2000和聚乙烯吡咯烷酮(PVP)20000作为表面活性剂和表面修饰剂,利用辉光放电等离子体射流产生的大量高能电子等活性粒子分解乙醇溶液制备碳纳米粒子。采用透射电子显微镜和荧光分光光度计对生成物的形貌和荧光特性进行了检测。结果表明,生成物为石墨相的荧光碳纳米颗粒。随着反应时间的延长,生成物的荧光强度增强;采用PEG-2000修饰后产物的荧光强度比采用PVP-20000更强;丝状放电模式下生成物的荧光强度高于辉光放电模式。制备的碳纳米颗粒的荧光量子产率为46.58%。     

热阴极辉光放电对金刚石膜沉积的影响

研究了在热阴极辉光放电等离子体化学气相沉积金刚石膜过程中，热阴极辉光放电特性与金刚石膜沉积工艺的关系．结果表明，适当的阴极温度是保证大电流、高气压辉光放电的必要条件．阴极的温度影响辉光放电阴极位降区的放电性质．金刚石膜的沉积速率随着气体压力(16～20kPa)的升高而上升，在18.6kPa左右出现最高值，而阳极位降区电场强度的降低使膜品质下降．放电电流(8～12A)对沉积速率的影响与气体压力的影响具有相似的规律．     

离子渗碳薄膜的新进展

利用乙烯作为保护气体,以射频溅射镀膜的方法,在各种表面上形成离子渗碳薄膜是70代末期研制成功的新型镀膜方法。离子渗碳薄膜具有可以进行选择的机械、光学和电学性能。工艺要求和技术条件较为复杂,是大有前途的新型镀膜方法之一。在射频辉光放电或直流辉光放电的时候,等离子使乙烯气体中的碳分裂沉积到镀材的表面后可以形成人造金刚石薄膜。正因为如此,射频离子渗碳技术引起了真空应用工作者的关注     

薄膜冶金技术的几种方法

本文介绍了几种薄膜冶金方法的使用。叙述了电子束共蒸发技术在蓝宝石表面上制备Nb_3Ge薄膜,辉光放电制备非晶硅太阳能电池光电薄膜,空心阴极放电法制取TiN薄膜和离子注入制备半导体器件薄膜的工艺及其对镀薄装置提出的要求。     

贫铀表面Ar气脉冲辉光放电清洗

贫铀极易氧化,为了提高其表面薄膜的结合性能,薄膜沉积前铀表面的辉光放电清洗是极为重要的。利用计算机模拟对Ar气脉冲辉光放电等离子体特性进行了研究,采用俄歇电子能谱仪(AES)对辉光放电清洗后铀表面化学元素进行了分析,同时对铀表面铝薄膜界面元素分布进行了深度剖析。结果表明:氩分压和脉冲电压是影响辉光放电等离子体特性的关键因素;脉冲电压和氩分压越高,辉光放电等离子体中Ar+密度越大;脉冲电压辉光放电清洗效果优于直流电压;在2.0Pa氩分压、-900V脉冲电压下,等离子体Ar+密度高达1.29×1014/m3,采用该参数对铀表面进行清洗可以获得洁净的表面,并有利于薄膜原子向铀基体内部迁移,促使膜基界面"伪扩散层"的增宽,从而增强铀表面薄膜的结合性能。     

理论分析辉光放电对碳纳米管生长速率的影响

利用负偏压增强热丝化学气相沉积，在沉积过渡层Ta和催化剂NiFe层的Si衬底上制备了碳纳米管，并用扫描电子显微镜研究了它们的形貌。发现辉光放电后，碳纳米管的平均长度比无辉光放电时大，并且随着负偏压的增大而增大，即辉光放电增大了它们的生长速率。结合辉光放电和扩散理论分析了辉光放电对碳纳米管生长速率的影响，结果表明在生长碳纳米管的过程中，由于辉光放电的产生，碳在催化剂中的活度得到增强，从而增大了碳纳米管的生长速率。     

低气压下空心阴极辉光放电等离子体的特性

为掌握10-2Pa～10-3Pa的低气压、磁场条件下空心阴极辉光等离子体的特性及其与常规辉光放电伏安特性的区别,我们对其伏安特性和电子密度进行了测量。实验结果表明:低气压、磁场条件下空心阴极辉光放电的整个过程可分为三个不同阶段,即随着电流的增大,依次为起辉阶段、空心阴极放电阶段和反常辉光放电阶段。其中,起辉阶段与空心阴极放电阶段的伏安特性与常规辉光放电的伏安特性曲线不同,而反常辉光放电阶段类似。实验证实了电子密度随电流增大而增大的关系,实验结果表明,在轴线方向上,阳极附近的电子密度大于阴极附近的;在与轴线垂直的平面上,电子密度差别不大。     

大气压氦气射频介质阻挡辉光放电的均匀性研究

为了研究大气压射频介质阻挡辉光放电的时空特性,采用一个表面覆盖有石英介质的铜电极和一个自制水电极的放电系统,在氦气中获得了大面积和较大电极间距下的辉光放电。对ICCD高速相机拍摄的径向放电图像和轴向放电图像分析揭示了射频介质阻挡辉光放电不仅具有较好的径向均匀性,而且具有很好的轴向均匀性,并不存在沿径向的发展。这是不同于中频介质阻挡辉光放电的一个显著特征。此外,注意到射频介质阻挡辉光放电在径向和轴向上的发展均与射频周期有很强的关联性。分析认为这是由于空间电荷在射频介质阻挡辉光放电的形成和发展中发挥主导作用。因此,可以认为射频介质阻挡辉光放电所具备非常好的径向和轴向均匀性,与中频介质阻挡辉光放电相比,可能会更有利于工业生产中进行均匀薄膜沉积和对薄膜表面改性处理等。     

低In电解液电沉积制备CuInSe2吸收层

通过线性电位扫描分析了低In电解液中的阴极电化学反应,结果表明柠檬酸钠可以降低Cu2+的活性,而H2SeO3的加入可导致阴极上Se元素与Cu+和In3+发生复杂的协同反应.低In电解液中恒电位沉积的薄膜与CIS的化学计量比相差较大,分段电位的恒电位沉积得到的薄膜更接近于CuInSe2(CIS)化学计量比.薄膜在N2气氛上退火处理,得到了黄铜矿结构CIS薄膜,禁带宽度为1.06eV.     

Amorphous carbon films in direct current magnetron sputtering from regenerative sooting discharge

We present results of carbon coatings on metal substrates in cylindrical hollow cathode (CHC) direct current magnetron sputtering. This is a new technique for making amorphous carbon films by CHC magnetron sputtering from a regenerative sooting discharge. The carbon films are deposited on Cu and Al substrates in a Ne atmosphere and compared with the films of carbon soot on the same materials produced from a conventional 80A arc discharge between graphite electrodes in a He background gas. Raman spectroscopy reveals the existence of graphite and diamond-like structures from the arc discharge while in CHC magnetron sputtering, graphite-like structures are dominant. X-ray diffraction data of samples from the arc discharge show nano-size precipitates of Al₄C₃ of rhombohedral and hexagonal form for the aluminium sample and probable formation of diamond and hexagonal carbon in copper whilst in magnetron sputtering we obtain amorphous carbon films. Scanning electron microscope images of the surface show a collection of loose agglomerates of carbon particles in the arc discharge whereas, for magnetron sputtering, structures are regular with smooth edges and fine grains.     

Amorphous carbon films in direct current magnetron sputtering from regenerative sooting discharge

We present results of carbon coatings on metal substrates in cylindrical hollow cathode (CHC) direct current magnetron sputtering. This is a new technique for making amorphous carbon films by CHC magnetron sputtering from a regenerative sooting discharge. The carbon films are deposited on Cu and Al substrates in a Ne atmosphere and compared with the films of carbon soot on the same materials produced from a conventional 80A arc discharge between graphite electrodes in a He background gas. Raman spectroscopy reveals the existence of graphite and diamond-like structures from the arc discharge while in CHC magnetron sputtering, graphite-like structures are dominant. X-ray diffraction data of samples from the arc discharge show nano-size precipitates of Al₄C₃ of rhombohedral and hexagonal form for the aluminium sample and probable formation of diamond and hexagonal carbon in copper whilst in magnetron sputtering we obtain amorphous carbon films. Scanning electron microscope images of the surface show a collection of loose agglomerates of carbon particles in the arc discharge whereas, for magnetron sputtering, structures are regular with smooth edges and fine grains.     

The structure of fullerene C60 films modified by helium glow discharge plasma

The structure of fullerene C₆₀ films modified by helium dc glow discharge plasma was studied using Raman scattering spectroscopy. The vibrational spectra of the C₆₀ films exhibit certain features depending on the plasma treatment duration. The helium ion bombardment leads to the degradation of the fullerene structure and the formation of an amorphous carbon phase. The coefficient of carbon sputtering by helium was estimated.     

Anwendung der Hohlkatodenplasmaquelle in der Vakuumtechnik

Various effective and simple constructed plasma sources can be developed by using the hollow cathode effect. The improve of the plasma efficiency is caused by the penetration of two or more glow regions of different parts of the cathode. The equatation p × d ∽ 1 mbar cm is a rule of thumb for the appearance of the hollow cathode effect. The hollow cathode arc discharge is caused by an additional thermal electron emission besides the effectes of the hollow cathode glow discharge. All this effects are the reason for the higher degree of ionization for a hollow cathode source in comparison with the most other plasma sources. Application of the hollow cathode glow discharge for surface finish are technics like plasmacleaning, electron beam ablation or gas flow sputtering. Latters are new technics which allow the development of new sources for the coating technology. The application of the hollow cathode are discharge is possible by using the thermal energy generated by the electron beam (electron beam heating, electron beam melting, and electron beam evaporation) and by using the different possibilities of coating technologies whith the hollow cathode arc source (plasma enhanced evaporation, plasma enhanced reactive PVD and plasma CVD).     

Operating characteristics of the hollow anode glow discharge ion source

In this work, a new shape of a glow discharge ion source with axial extraction has been designed and constructed. High output ion beam current can be extracted axially in a direction normal to the discharge region without using extraction system. Optimization of the distance between the anode and the cathode has been determined using argon gas. It is found that the optimum gap distance between the anode and the cathode is equal to 3.5 mm, where stable discharge current and maximum output ion beam current can be obtained. The discharge characteristics of the ion source at different operating gas pressures have been measured at this optimum distance between the anode and the cathode. A disk of Teflon insulator has been put between the anode and the cathode. This disk was covering the cathode area and reducing the discharge area on the cathode surface for discharge confinement, therefore, a higher output ion beam current could be obtained.     

Ion bombardment effects in plasma deposition of hydrogenated amorphous silicon carbide films: A comparative study of d.c. and r.f. discharges

The structure and the properties of hydrogenated amorphous silicon carbide films produced at room temperature by d.c. and r.f. glow discharge decomposition of silane and ethylene were studied with a systematic control of the ion flux at the surface of the growing film. The composition and structure of the films were monitored by measuring their IR absorption, their refractive index and their optical gap. The ion fluxes were determined from the saturation current of a small grid probe located in the substrate holder.It was found that d.c. cathodic and r.f. films show an inorganic structure with a dispersed carbon phase while d.c. anodic films exhibit mainly hydrogenated carbon clusters. These structural changes are thought to result from differences in the energies of the bombarding ions.The versatility of the r.f. and d.c. proximity discharges in comparison with d.c. discharges (anodic and cathodic films) is also emphasized.     

D.C. cathode sputtering: influence of the oxygen content in the gas flow on the discharge current

A qualitative physical model is proposed to explain the influence of the oxygen content in the gas flow on the discharge current for reactive cathode sputtering in a d.c. diode system. According to this model the increase in the oxygen content affects the discharge current density in two main ways: (i) by a sharp change in the coefficient of secondary ion-electron emission from the target surface as a result of its oxidation; and (ii) by the influence of the oxygen content on the elementary ionization processes in the discharge region near the cathode as a result of the transition from a glow discharge in a noble gas to a glow discharge in oxygen.The results of the experimental investigations with targets of different materials under different sputtering conditions were in good agreement with the conclusions from the proposed physical model. Experiments aimed at elucidating the mechanism of formation of an oxide layer by sputtering of a silicon target have also been carried out. The conclusions can be useful for thin film deposition as well as for investigations of secondary emission from surfaces in a glow discharge.     

Diamond-like a-C:H coatings deposited in a non-self-sustained discharge with plasma cathode

Hydrogenated amorphous carbon (a-C:H) coatings have been obtained by means of acetylene decomposition in a non-self-sustained periodic pulse discharge (2A, 50 kHz, 10 μs) with hollow cathode. The discharge operation was maintained by plasma cathode emission with grid stabilization based on dc glow discharge. Using the proposed method, it is possible to control the deposition conditions (total pressure of the Ar + C₂H₂ mixture, partial pressure of C₂H₂, ion current density, carbon ion energy) within broad limits, to apply a-C:H coatings onto large-area articles, and to perform deposition in one technological cycle with ion etching and ion implantation treatments aimed at improving the adhesion of coatings to substrates (Ti, Al, stainless steel, VK8 hard alloy) at temperatures below 150°C. Results of determining the deposition rate (1–8 μm), the nanohardness of coatings (up to 70 GPa), and the fraction of sp ³ bonds (25–70%) in the diamond-like coating material are presented.     

Calculation of the electrode surface temperature in the normal glow discharge

The two-dimensional non-stationary heat conduction equation is analytically solved in the volume of the cylindrical cathode with the normal glow discharge spot at one of its ends. A system of equations connecting the cathode surface temperature in the spot after discharge ignition to the discharge cathode sheath parameters is formulated, and the temperature time dependence for discharge in helium is calculated, taking into account the influence of background gas heating on the spot radius.