金刚石微米聚晶结构的生长及其场发射特性研究

在覆盖金属钛层的陶瓷上,利用微波等离子体化学气相沉积(MPCVD)法制备出类球状微米金刚石聚晶薄膜.利用扫描电子显微镜、拉曼光谱、X射线衍射,分析了薄膜的结构和表面形貌.测试了类球状微米金刚石聚晶膜的场致电子发射特性.开启电场仅为0.55V/μm,在2.18V/μm的电场下,其场发射电、流密度高达11mA/cm2.对类球状微米金刚石聚晶阵列形成机理和场发射机理进行了研究.     

氢等离子体处理对类金刚石膜场发射性能的影响

采用大功率、高重复频率、准分子激光溅射热解石墨靶制备了类金刚石膜,研究了直流辉光氢等离子体处理对类金刚石膜的场发射性能的影响。结果表明:氢等离子体处理后,类金刚石膜的场发射性能明显提高,其发射阈值电场由26V/μm下降到19V/μm。氢等离子体刻蚀除去了类金刚石膜生长表面的富含石墨的薄层,露出的新表面具有较低的功函数;膜表面的悬键被氢原子饱和,进一步降低了电子亲和势,改善了膜的场发射性能。     

氢、氧等离子体处理对氮化硼薄膜场发射特性的影响

用RF磁控溅射的方法在Si(100)基底上沉积了纳米氮化硼薄膜,然后分别用氢、氧等离子体对薄膜表面进行了处理,用红外光谱、原子力显微镜、光电子能谱以及场发射试验对薄膜进行了研究,结果表明氢等离子体使BN薄膜表面NEA增加,阈值电场降低,发射电流明显增大.氧等离子体处理对BN薄膜的场发射特性影响不大,只是发射电流略有降低,这只能是由于氧化层存在的原因.     

MPCVD法在氧化铝陶瓷上的金刚石膜沉积及其成核分析

用微波等离子体化学气相沉积（ＭＰＣＶＤ）法在氧化铝陶瓷基片上沉积了金刚石薄膜。实验表明，对基片进行适当的预处理，包括用金刚石研磨膏仔细研磨和沉积前原位沉积一层无定形碳层，可显著提高成核密度；对硅衬底和氧化铝基片上金刚石膜的成核过程进行了对比分析，并提出了提高氧化铝基片上沉积金刚石的成核的措施。     

大面积印刷纳米金刚石薄膜的场致发射的研究

研制了特定比例的纳米金刚石浆料,采用了丝网印刷工艺在石墨衬底上大面积印制了纳米金刚石场发射薄膜,实验探索了石墨衬底纳米金刚石薄膜的烧结工艺和后处理过程,利用扫描电镜(SEM)观察了纳米金刚石膜的表面形貌,经后处理的薄膜中纳米金刚石露出薄膜表面,纳米金刚石的棱角是天然的发射体.采用本课题组研制的多功能场发射测试台在10-6Pa的真空条件下进行了场发射特性的测试,结果发现石墨上低成本大面积印刷的纳米金刚石薄膜具有均匀稳定的场发射特性,作为电子器件的理想冷阴极发射,可在宇宙飞船、原子反应堆等恶劣条件下工作的平面显示器中得到应用.     

类金刚石薄膜的获得和应用

类金刚石薄膜是七十年代初期出现的新型非金属薄膜材料之一.这种与金刚石的特性相接近的薄膜具有优良的耐磨、耐蚀性以及许多优良的光学性能.在文章的第二部分介绍了离子束沉积和等离子沉积两种获得类金刚石薄膜的原理和方法,其中,离子束沉积法又分为低能碳离子束沉积法和双离子束及磁控溅射石墨沉积法两种:等离子体沉积法又分为辉光放电等离子体沉积法和大面积微波放电沉积法两种.介绍了薄膜的组分与结构和主要的沉积条件的关系.第三部分介绍了薄膜的物理性能、机械性能、光学性能.在介绍的同时继续以具体的文献说明主要的沉积条件对这些特性的影响.最后展望了类金刚石薄膜在8个方面的应用.文末附有参考文献19篇.     

微米及纳米金刚石薄膜的制备及其组织性能研究.

采用微波等离子体化学气相沉积(MPCVD)方法在铜衬底上沉积了微米和纳米两种金刚石薄膜,过渡层均为钛一铝一钼.用场发射扫描电子显微镜(FESEM)观察薄膜的表面及断面形貌,用拉曼(Raman)光谱测量所得金刚石薄膜的质量,利用压痕法测试了所得薄膜的附着性能,研究结果表明:过渡层可有效提高微米金刚石薄膜在铜衬底上的附着力,反应气氛中Ar的存在可促使纳米金刚石薄膜的形成,改善薄膜表面的粗糙度.     

WC-Co硬质合金表面MW-PCVD制备金刚石薄膜去钴预处理的研究

研究了ＷＣ－Ｃｏ硬质合金刀具表面微波等离子体化学气相沉积（ＭＷ－ＰＣＶＤ）制备金刚石薄膜时不同的去钴预处理方式的影响。扫描电子显微镜形貌观察和喇曼谱分析表明，利用氢－氧等离子体处理方式有显著的去钴效果，相应沉积获得的金刚石薄膜质量相对较高。与酸腐蚀处理相比，微波等离子体化学气相沉积装置中实现氢－氧等离子体处理方式具有独特的优越性。     

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．     

WC—Co硬质合金表面MW—PCVD制备金刚石薄膜去钴预处理的研究

研究了ＷＣ－Ｃｏ硬质合金刀具表面微波等离子体化学气相沉积（ＭＷ－ＰＣＶＤ）制备金刚石薄膜时不同的去钴预处理方式的影响。扫描电子显微镜形貌观察和喇曼谱分析表明，利用氢－氧等离子体处理方式有显著的去钴效果，相应沉积获得的金刚石薄膜质量相对较高。与酸腐蚀处理相比，微波等离子体化学气相沉积装置中实现氢－氧等离子体处理方式具有独特的优越性。     

The effects of plasma pre-treatment and post-treatment on diamond-like carbon films synthesized by RF plasma enhanced chemical vapor deposition

Diamond-like carbon (DLC) films were synthesized by RF plasma enhanced chemical vapor deposition and the effects of plasma pre-treatment and post-treatment on the DLC films were investigated. Experimental results show that the surface roughness of the substrate, ranging from 0.2 to 1.2 nm, created by the plasma pre-treatment, will affect the surface roughness of the DLC films deposited using methane as the carbon source. However, the film surface roughness (0.1-0.4 nm) is much smaller than that of the substrate. Raman analysis and hardness measurement by nanoindentation indicate that the structure and the hardness of the DLC films are relatively unchanged for the film surface roughness investigated. For the argon or hydrogen plasma post-treatment of the DLC films deposited using acetylene as the carbon source, it is found that surface roughness decreases with the post-treatment time. Although the hardness decreases after post-treatment, it remains relatively constant with increasing post-treatment time.     

CVD of hard DLC films in a radio frequency inductively coupled plasma source

Chemical vapor deposition (CVD) of hard diamond-like carbon (DLC) films on silicon (100) substrates from methane was successfully carried out using a radio frequency (r.f.) inductively coupled plasma source (ICPS). Different deposition parameters such as bias voltage, r.f. power, gas flow and pressure were involved. The structures of the films were characterized by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The hardness of the DLC films was measured by a Knoop microhardness tester. The surface morphology of the films was characterized by atomic force microscope (AFM) and the surface roughness (R_a) was derived from the AFM data. The films are smooth with roughness less than 1.007 nm. Raman spectra shows that the films have typical diamond-like characteristics with a D line peak at 1331 cm⁻¹ and a G line peak at 1544 cm⁻¹, and the low intensity ratio of I_D/I_G indicate that the DLC films have a high ratio of sp³ to sp² bonding, which is also in accordance with the results of FTIR spectra. The films hardness can reach approximately 42 GPa at a comparatively low substrate bias voltage, which is much greater than that of DLC films deposited in a conventional r.f. capacitively coupled parallel-plate system. It is suggested that the high plasma density and the suitable deposition environment (such as the amount and ratio of hydrocarbon radicals to atomic or ionic hydrogen) obtained in the ICPS are important for depositing hard and high quality DLC films.     

X-ray reflectivity study of bias graded diamond like carbon film synthesized by ECR plasma

Diamond like carbon (DLC) coatings were deposited on silicon substrates by microwave electron cyclotron resonance (ECR) plasma CVD process using plasma of Ar and CH ₄ gases under the influence of negative d.c. self bias generated on the substrates by application of RF (13·56 MHz) power. The negative bias voltage was varied from ?60 V to ?150 V during deposition of DLC films on Si substrate. Detailed X-ray reflectivity (XRR) study was carried out to find out film properties like surface roughness, thickness and density of the films as a function of variation of negative bias voltage. The study shows that the DLC films constituted of composite layer i.e. the upper sub surface layer followed by denser bottom layer representing the bulk of the film. The upper layer is relatively thinner as compared to the bottom layer. The XRR study was an attempt to substantiate the sub-plantation model for DLC film growth.     

Emission properties of DLC films on Si substrates

DLC films were deposited on polished both n-type and p-type silicon substrates. The silicon resistivity was ～0.02 Θ cm. Some of the DLC films 20 nm thick were deposited on the n-type Si surface with the submicron cones. SEM and Raman spectroscopy were used for structural investigations. Field electron emission occurs after dielectric breakdown, except for the samples with Si cones for which the emission seems to originate from SiC formed during the first stage of electron emission. It seems that too much sp² graphite phase may give rise to the observed increase in the turn-on field from 50 V/μm up to 150 V/μm.     

Surface characterization and nanomechanical properties of diamond-like carbon films synthesized by RF plasma enhanced chemical vapor deposition

Diamond-like carbon (DLC) films were synthesized by RF plasma enhanced chemical vapor deposition using acetylene as the carbon source and the effects of acetylene/nitrogen ratio in the reaction atmosphere, deposition pressure, and plasma post-treatment using different atmospheres on the surface roughness and mechanical properties of DLC films were investigated. Although the surface roughness, characterized by AFM, decreased as the acetylene/nitrogen ratio in the reaction atmosphere decreased, the hardness of DLC films measured by nanoindentation also decreased with the decrease of the acetylene/nitrogen ratio, which is consistent with the Raman results of the I_D/I_G ratio. Rougher films with higher residual stress were obtained when using a deposition pressure higher than 40.0 Pa (0.3 torr). For the effect of plasma post-treatment using different atmospheres, surface smoothing was found for the hydrogen plasma post-treatment, whereas nitrogen and argon plasma post-treatments resulted in surface roughening. Hydrogen plasma post-treatment was found to lower the surface roughness without significantly sacrificing the hardness.     

Influence of hydrogen on the mechanical properties and microstructure of DLC films synthesized by r.f.-PECVD

This paper aims to investigate the influence of hydrogen on the variation of mechanical properties and microstructure of diamond-like carbon (DLC) films synthesized by radio frequency plasma chemical vapor deposition (r.f.-PECVD). The DLC films were deposited on a silicon substrate (p-type). The reactant gases employed in this paper are a mixture of acetylene and hydrogen. The ratio of hydrogen in the gas mixture was successively varied to clarify its influence on the roughness, thickness, microstructure, hardness, modulus, residual stress and wear depth for the DLC films. The results reveal that increasing the concentration of hydrogen decreases thickness and roughness. Meanwhile, increasing the hydrogen concentration causes the decrease of sp³ ratio, hardness as well as modulus. Finally, wear behavior is correlated to the surface morphology and hydrogen concentration for deposition with hydrogen-containing reactant gas.     

Study of the ability to field emission from diamond-like carbon layers and carbon nanotubes

The aim of this work was to study the relationship between parameters of the electron field emission and the film deposition method. In this study two methods were applied: classical radio frequency plasma-assisted chemical vapor deposition (RF PACVD) to produce diamond-like carbon (DLC) layers and chemical vapor deposition (CVD) to produce carbon nanotubes (CNT). DLC layers were grown on n-type silicon substrates and CNT were grown on n-type and p-type silicon substrates.Atomic force microscopy (AFM) and Raman spectroscopy were used to investigate the physical and chemical parameters of DLC films after deposition process. The electrical parameters of capacitors with the DLC layer as an insulator were extracted from the capacitance-voltage (C-V) and current-voltage (I-V) characteristics. Measurements of the field emission were performed after characterization of the layer properties.     

射频磁控溅射制备类金刚石薄膜的特性

采用射频磁控溅射技术,用高纯石墨靶在单晶硅片、抛光不锈钢片上制备了类金刚石薄膜(DLC)。采用Raman光谱、原子力显微镜、显微硬度分析仪,表征了类金刚石薄膜的微观结构、表面形貌、硬度。结果表明,制备的类金刚石薄膜中含sp2、sp3杂化碳键,具有典型的类金刚石结构特征。计算表明,对应sp3杂化碳原子含量的ID1IG为3.18;薄膜的表面十分平整光滑,表面粗糙度极低,平均粗糙度Ra为0.17 nm;薄膜硬度可以高达30.8 GPa。     

Improved electrochemical performance of nitrocarburised stainless steel by hydrogenated amorphous carbon thin films for bone tissue engineering

In this study, hydrogenated amorphous carbon thin films, structurally similar to diamond‐like carbon (DLC), were deposited on the surface of untreated and plasma nitrocarburised (Nitrocarburizing‐treated) stainless steel medical implants using a plasma‐enhanced chemical vapour deposition method. The deposited DLC thin films on the nitrocarburising‐treated implants (CN+DLC) exhibited an appropriate adhesion to the substrates. The results clearly indicated that the applied DLC thin films showed excellent pitting and corrosion resistance with no considerable damage on the surface in comparison with the other samples. The CN+DLC thin films could be considered as an efficient approach for improving the biocompatibility and chemical inertness of metallic implants.Inspec keywords: tissue engineering, bone, biomedical materials, electrochemistry, amorphous state, carbon, hydrogen, thin films, plasma CVD, adhesion, corrosion resistance, surface hardeningOther keywords: electrochemical performance, plasma nitrocarburised stainless steel medical implants, hydrogenated amorphous carbon thin films, bone tissue engineering, plasma‐enhanced chemical vapour deposition method, adhesion, corrosion resistance, biocompatibility, chemical inertness, metallic implants, C:H     

Field electron emission from hydrogen plasma treated nano-ZnO thin films

A nano-Zno films are deposited on the Mo film/ceramic substrates by using the electron beam vapor deposition technique. Then a hydrogen plasma treated method is used to improve the characteristics of ZnO thin films by microwave plasma chemical vapor deposition system. Effects of process parameters on morphologies and structures of the ZnO thin films are detected and analysed by field emission scanning electron microscopy, X-ray diffraction spectrum and energy dispersive spectrum. The experimental result indicates that the hydrogen plasma treated techniques can essentially reduce the surface resistance and improve the field emission current density of the nano-ZnO thin films. For the hydrogen plasma treated sample, its field emission current density can increased more than three times at 2.2 V/microm electric field condition.