工艺条件对热丝CVD金刚石薄膜电学性能的影响

采用不同的沉积条件,通过HFCVD方法制备了四种不同质量、不同取向的CVD金刚石薄膜．讨论了薄膜退火前后的介电性能．研究了不同沉积条件和退火工艺与介电性能之间的联系．通过扫描电镜SEM、Raman光谱、XRD、I-V特性曲线以及阻抗分析仪表征CVD金刚石薄膜的特性．结果表明,退火工艺减少了薄膜吸附的氢杂质,改善了薄膜质量．获得的高质量CVD金刚石薄膜具有好的电学性能,在50V偏压条件下电阻率为1．2×1011Ω·cm,频率在2MHz条件下介电常数为5．73,介电损耗为0．02．

掺硼浓度对金刚石薄膜二次电子发射特性的影响

掺硼金刚石薄膜具有负电子亲和势和良好的电子运输性能且容易制备,作为冷阴极材料在图像显示技术和真空技术等领域都存在巨大的应用价值,引起人们的广泛关注。采用MPCVD法利用氢气、甲烷和硼烷的混合气体,制备出不同浓度的掺硼金刚石薄膜。结果表明,掺硼浓度影响金刚石薄膜的物相结构、组织形貌,进而影响其二次电子发射性能,当硼烷的流量为4mL/min时,制备的金刚石薄膜质量最好,二次电子发射系数约为90。

PVD薄膜传感器的振动疲劳裂纹监测可行性研究

为确定将离子镀膜技术制备的物理气相沉积(PVD)薄膜传感器用于监测振动疲劳裂纹的可行性,开展了以PVD薄膜传感器和2A12-T4铝合金试验件为对象的研究。通过有限元仿真分析确定了试验件易产生裂纹的位置,并通过离子镀膜技术完成了PVD薄膜传感器的制备。对比了不同表面处理状态试验件的共振频率与振动幅值的变化和疲劳强度,应用显著性分析方法分析了制备PVD薄膜传感器的过程对基体振动响应特性的影响。使用逐步加载法对不同表面处理状态的试验件进行了振动疲劳试验,并对其疲劳强度进行了对比。进行了2A12-T4铝合金试验件的振动疲劳裂纹初步监测试验,对制备有PVD薄膜的试验件的指定点电位差进行了测量。研究结果表明:PVD薄膜传感器的制备过程不会对基体振动响应特性和振动疲劳性能产生不利影响;PVD薄膜传感器与基体具有良好的损伤一致性;PVD薄膜传感器适用于普通基体的振动疲劳裂纹监测。

磁控溅射含铜CrN薄膜的结构和抗菌性能

本研究采用反应磁控溅射技术制备了不同铜含量的CrNCu抗菌薄膜。台阶轮廓仪、扫描电镜、电子能谱和X射线衍射分析表明,随着铜靶电流的增大,薄膜的沉积速率和Cu含量升高,CrN和Cr含量下降,但粗糙度在0.9~1.4 nm之间。接触角测试表明CrNCu薄膜具有高疏水性和低表面能,其表面水滴的干燥时间长于玻璃试样。平板计数和模拟环境下的喷雾菌液实验表明,CrNCu薄膜对大肠杆菌具有良好的抗菌性能。

薄膜材料与器件

O484.1 2000010458激光辅助化学气相沉积金刚石薄膜实验研究=Synthesisof diamond films by laser-assistedchemical vapour deposition[刊,中]/任德明,胡孝勇,刘逢梅,赵景山,王楠楠,马祖光（哈尔滨工业大学光电子技术研究所.黑龙江,哈尔滨（150001））//光电子·激光.—1998,9（6）.—446-449采用激光辅助化学气相沉积法合成了厚度为15μm的金刚石薄膜。实验结果表明:以丙酮为碳源气体,并用XeCl（308 nm）准分子激光解离,H2用灯丝进行预先解离,适当选择和控制各种实验参数,可获得高质量的金刚石薄膜。还讨论了衬底温度以及灯丝温度等实验参数对薄膜生长速率与薄膜质量的影响。图9表1参8（郑锦玉）O484.2 2000010459离化团束沉积中的分子动力学模拟=Molecular dynamicssimulation in ionized clusterbeams deposition[刊,中]/张豪,夏宗宁（清华大学材料科学与工程系.北京（100084））//人工晶体学报.—1998,27（4）.

真空辐射加热基片的温度分布

真空辐射加热下基片表面温度分布的均匀性是薄膜制备中的关键问题之一．采用数值计算和比色红外测温两种方法,研究了作者自行研制的真空辐射加热器(IMCAS-VRH)的性能．利用IMCAS—VRH加热直径6in的单晶硅基片,当电功率为3860W时,基片表面平均温度为1093K,整个基片上的温度变化的测量值约为6 K．基片表面温度分布的计算结果与测量数据符合得很好,进一步的计算分析表明钼丝对辐射的遮挡效应、隔热屏和基片热传导等对基片温度分布均匀性有重要影响．

ZnO Films Synthesized by Solid-Source Chemical Vapor Deposition with c-Axis Parallel to Substrate

ZnO films with c -axis parallel to the substrate are reported.ZnO films are synthesized by solid-source chemical vapor deposition,a novel CVD technique,using zinc acetate dihydrate (solid) as the source material.The properties are characterized by X-ray diffraction,atomic force microscopy and transmission spectra.The parallel oriented ZnO films with mixed orientation for (100) and (110) planes are achieved on glass at the substrate temperature of 200℃ and the source temperature of 280℃,and a qualitative explanation is given for the forming of the mixed orientation.AFM images show that the surface is somewhat rough for the parallel oriented ZnO films.The transmission spectrum exhibits a high transmittance of about 85% in the visible region and shows an optical band gap about 3.25eV at room temperature.

Effect of deposition parameters on micro-and nano-crystalline diamond films growth on WC-Co substrates by HFCVD

The characteristics of hot filament chemical vapor deposition（HFCVD） diamond films are significantly influenced by the deposition parameters, such as the substrate temperature, total pressure and carbon concentration. Orthogonal experiments were introduced to study the comprehensive effects of such three parameters on diamond films deposited on WC-Co substrates. Field emission scanning electron microscopy, atomic force microscopy and Raman spectrum were employed to analyze the morphology, growth rate and composition of as-deposited diamond films. The morphology varies from pyramidal to cluster features with temperature decreasing. It is found that the low total pressure is suitable for nano-crystalline diamond films growth. Moreover, the substrate temperature and total pressure have combined influence on the growth rate of the diamond films.

Preparation, characterization and electrochemical properties of boron-doped diamond films on Nb substrates

A series of boron-doped polycrystalline diamond films were prepared by hot filament （HF） chemical vapor deposition on Nb substrates. The effects of B/C ratio of reaction gas on film morphology, growth rate, chemical bonding states, phase composition and electrochemical properties of each deposited sample were studied by scanning electron microscopy, Raman spectra, X-ray diffraction, microhardness indentation, and electrochemical analysis. Results show that the average grain size of diamond and the growth rate decrease with increasing the B/C ratio. The diamond films exhibit excellent adhesion under Vickers microhardness testing （9.8 N load）. The sample with 2% B/C ratio has a wider potential window and a lower background current as well as a faster redox reaction rate in H2SO4 solution and KFe（CN）6 redox system compared with other doping level electrodes.

EFFECT OF GRID BIAS ON DEPOSITION OF NANOCRYSTALLINE DIAMOND FILMS

A positive grid bias and a negative substrate bias voltages are applied to the self-made hot filament chemical vapor deposited （HFCVD） system. The high quality nanocrystalline diamond （NCD） film is successfully deposited by double bias voltage nucleation and grid bias voltage growth. The Micro-Raman XRD SEM and AFM are used to investigate the diamond grain size, microstructure, surface morphology, and nucleation density. Results show that the obtained NCD has grain size of about 20 nm. The effect of grid bias voltage on the nucleation and the diamond growth is studied. Experimental results and theoretical analysis show that the positive grid bias increases the plasma density near the hot filaments, enhances the diamond nucleation, keeps the nanometer size of the diamond grains, and improves the quality of diamond film.

Si-doped diamond films prepared by chemical vapour deposition

The effects of Si doping on morphology, components and structure characteristics of CVD diamond films were studied. Si-doped CVD diamond films were deposited on Si substrate by adding tetraethoxysilane （TEOS） into acetone as source of reactant gas. The morphology and microstructure of diamond films were characterized by scanning electron microcopy （SEM）. The crystalline quality of diamond films was studied by Raman spectroscopy and X-ray diffractometry （XRD）. The surface roughness of the films was evaluated with surface profilometer. The results suggest that Si doping tends to reduce the crystallite size, enhance grain refinement and inhibit the appearance of （11 I） facets. Raman spectra indicate that Si doping can enhance the formation of sp2 phase in diamond films. Moreover, Raman signal of SiC was detected, which suggests the existence of Si in the diamond films. Smooth fine-grained diamond （SFGD） film was synthesized at Si to C ratio of 1%.

Amorphous SiO_2 interlayers for deposition of adherent diamond films onto WC-Co inserts

Amorphous Si O2（a-Si O2） films were synthesized on WC-Co substrates with H2 and tetraethoxysilane（TEOS） via pyrolysis of molecular precursor.X-ray diffraction（XRD） pattern shows that silicon-cobalt compounds form at the interface between a-Si O2 films and WC-Co substrates.Moreover,it is observed by transmission electron microscope（TEM） that the a-Si O2 films are composed of hollow mirco-spheroid a-Si O2 particles.Subsequently,the a-Si O2 films are used as intermediate films and chemical vapor deposition（CVD） diamond films are deposited on them.Indentation tests were performed to evaluate the adhesion of bi-layer（a-Si O2 ＋ diamond） films on cemented carbide substrates.And the cutting performance of bi-layer（a-Si O2 ＋ diamond） coated inserts was evaluated by machining the glass fiber reinforced plastic（GFRP）.The results show that a-Si O2 interlayers can greatly improve the adhesive strength of diamond films on cemented carbide inserts;furthermore,thickness of the a-Si O2 interlayers plays a significant role in their effectiveness on adhesion enhancement of diamond films.

Effect of deposition temperature on properties of boron-doped diamond films on tungsten carbide substrate

Boron-doped diamond(BDD)films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850°C by hot filament chemical vapor deposition(HFCVD)method.The effect of deposition temperature on the properties of the boron-doped diamond films on tungsten carbide substrate was investigated.It is found that boron doping obviously enhances the growth rate of diamond films.A relatively high growth rate of 544 nm/h was obtained for the BDD film deposited on the tungsten carbide at 650°C.The added boron-containing precursor gas apparently reduced activation energy of film growth to be 53.1 kJ/mol,thus accelerated the rate of deposition chemical reaction.Moreover,Raman and XRD analysis showed that heavy boron doping(750 and 850°C)deteriorated the diamond crystallinity and produced a high defect density in the BDD films.Overall,600-700°C is found to be an optimum substrate temperature range for depositing BDD films on tungsten carbide substrate.

Influence of methane on hot filament CVD diamond films deposited on high-speed steel substrates with WC-Co interlayer

Diamond films were deposited on high-speed steel substrates by hot filament chemical vapor deposition （HFCVD） method. To minimize the early formation of graphite and to enhance the diamond film adhesion, a WC-Co coating was used as an interlayer on the steel substrates by high velocity oxy-fuel spraying. The effects of methane content on nucleation, quality, residual stress and adhesion of diamond films were investigated. The results indicate that the increasing methane content leads to the increase in nucleation density, residual stress, the degradation of quality and adhesion of diamond films. Diamond films deposited on high-speed steel （HSS） substrate with a WC-Co interlayer exhibit high nucleation density and good adhesion under the condition of the methane content initially set to be a higher value （4%, volume fraction） for 30 min, and then reduced to 2% for subsequent growth at pressure of 3 kPa and substrate temperature of 800 ℃.

Nanoindentation tests on single crystal copper thin film with an AFM

Nanoindentation tests performed in a commercial atomic force microscope have been utilized to directly measure the elastic modulus and the hardness of single crystal copper thin films fabricated by the vacuum vapor deposition technique. Nanoindentation tests were conducted at various indentation depths to study the effect of indentation depths on the mechanical properties of thin films. The results were interpreted by using the Oliver-Pharr method with which direct observation and measurement of the contact area are not required. The elastic modulus of the single crystal copper film at various indentation depths was determined as (67.0±(6.9) GPa) on average which is in reasonable agreement with the results reported in literature. The indentation hardness constantly increases with decreasing indentation depth, indicating a strong size effect.

Chemical Vapor Deposition Mechanism of Copper Films on Silicon Substrates

A versatile metal-organic chemical vapor deposition （MOCVD） system was designed and constructed. Copper films were deposited on silicon （100） substrates by chemical vapor deposition （CVD） using Cu（hfac）2 as a precursor. The growth of Cu nucleus on silicon substrates by H2 reduction of Cu（hfac）2 was studied by atomic force microscopy and scanning electron microscopy. The growth mode of Cu nucleus is initially Volmer-Weber mode （island）, and then transforms to Stranski-Rastanov mode （layer-by-layer plus island）. The mechanism of Cu nucleation on silicon （100） substrates was further investigated by X-ray photoelectron spectroscopy. From Cu2p, O1s, F1s, Si2p patterns, the observed C=O, OH and CF3/CF2 should belong to Cu（hfac） formed by the thermal dissociation of Cu（hfac）2. H2 reacts with hfac on the surface, producing OH. With its accumulation, OH reacts with hfac, forming HO-hfac, and desorbs, meanwhile, the copper oxide is reduced, and thus the redox reaction between Cu（hafc）2 and H2 occurs.

Enhanced Property of Thin Cuprous Oxide Film Prepared through Green Synthetic Route

Thin cuprous oxide films have been prepared by chemical vapor deposition(pulsed spray evaporation-chemical vapor deposition)method without post-treatment.The synthesis of cuprous oxide was produced by applying a water strategy effect.Then,the effect of water on the morphology,topology,structure,optical properties and surface composition of the obtained films has been comprehensively investigated.The results reveal that a pure phase of Cu2O was obtained.The introduction of a small quantity of water in the liquid feedstock lowers the band gap energy from 2.16 eV to 2.04 eV.This finding was mainly related to the decrease of crystallite size due to the effect of water.The topology analyses,by using atomic force microscope,also revealed that surface roughness decreases with water addition,namely more uniform covered surface.Moreover,theoretical calculations based on density functional theory method were performed to understand the adsorption and reaction behaviors of water and ethanol on the Cu2O thin film surface.Formation mechanism of the Cu2O thin film was also suggested and discussed.

Dependence of surface morphology of CVD diamond films on deposition conditions

The diamond films have been deposited by the hot filament CVD method on molybdenum substrates from the mixture reactant gas of acetone and hydrogen.The surface morphologies of the obtained diamond films under various deposition conditions have been observed by scanning electron microscope(SEM).The experimental results strongly indicate that the surface morphologies of the resulting films have closely related to the deposition conditions,i.e.,reaction pressure.For molybdenum substrates,under the lower reaction pressure the surface morphologies of the grains comprising the resulting films mainly display the small single crystal cubo-octahedron and double small crystal cubo-octahedron;under the higher reaction pressure,the surface morphologies mainly display the large cauliflower-like.These results show that there are various crystal habits for CVD diamond under various deposition conditions.

Dependence of Optical Absorption in Silicon Nanostructures on Size of Silicon Nanoparticles

The amorphous silicon nanoparticles （Si NPs） embedded in silicon nitride （SiNx） films prepared by helicon wave plasma-enhanced chemical vapor deposition （HWP-CVD） technique are studied. From Raman scattering investigation, we determine that the deposited film has the structure of silicon nanocrystals embedded in silicon nitride （nc-Si/SiNx） thin film at a certain hydrogen dilution amount. The analysis of optical absorption spectra implies that the Si NPs is affected by quantum size effects and has the nature of an indirect-band-gap semiconductor. Further, considering the effects of the mean Si NP size and their dispersion on oscillator strength, and quantum-confinement, we obtain an analytical expression for the spectral absorbance of ensemble samples. Gaussian as well as lognormal size-distributions of the Si NPs are considered for optical absorption coefficient calculations. The influence of the particle size-distribution on the optical absorption spectra was systematically studied. We present the fitting of the optical absorption experimental data with our model and discuss the results.

Growth and low-energy electron microscopy characteri- zation of monolayer hexagonal boron nitride on epitaxial cobalt

Low-energy electron microscopy （LEEM） has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride （h-BN） films. The h-BN films are grown on heteroepitaxial Co using chemical vapor deposition （CVD） at low pressure. Our findings from LEEM studies include the growth of monolayer film having two, oppositely oriented, triangular BN domains commensurate with the Co lattice. The growth of h-BN appears to be self-limiting at a monolayer, with thicker domains only appearing in patches, presumably initiated between domain boundaries. Reflectivity measurements of the thicker h-BN films show oscillations resulting from the resonant electron transmission through quantized electronic states of the h-BN films, with the number of minima scaling up with the number of h-BN layers. First principles density functional theory （DFT） calculations show that the positions of oscillations are related to the electronic band structure of h-BN.