Microwave and hot filament chemical vapour deposition of diamond multilayers on Si and WC-Co substrates

A serious problem in the use of chemical-vapour-deposited polycrystalline diamond coatings in electronics, optics as well as in cutting tools is the high surface roughness. In our work, microcrystalline and nanocrystalline diamond films with a thickness of 0.5-5 μm were deposited using microwave chemical vapour deposition (MW CVD), and with a thickness of 1-4 μm by hot filament chemical vapour deposition (HF CVD). For both deposition technologies, we investigated the effect of a negative bias upon the formation of microcrystalline and nanocrystalline diamond multilayers. In the cases of smooth Si and relief WC-Co substrate surfaces, the multilayers were found to have a “cauliflower” look. The structure and composition of deposited layers were checked by scanning electron microscopy and Raman spectroscopy.     

Highly rectifying Au-contacts on diamond-on-silicon substrate

Au Schottky diodes have been fabricated on highly oriented diamond (HOD) films, grown on silicon using AC-bias nucleation and microwave plasma chemical vapor deposition. The active layers were selectively grown and doped by solid boron source. High rectification ratios were obtained up to 500°C in a bias voltage range up to ±15 V. A current density of more than 1 A/cm² and a breakdown field strength up to 2.0·10⁶ V/cm for point contacts has been demonstrated     

CVD金刚石膜用作TaN2热敏打印头表面保护层的研究

报道了用微波等离子体化学气相淀积技术在ＴａＮ２电阻材料上淀积高质量金刚石薄膜的制备工艺，以及扫描电镜、Ｘ射线衍射、拉曼光谱、压痕测试的测试结果。探讨了提高金刚石膜在非金刚石衬底成核密度与粘附性的实验方法，从实验上证实了ＣＶＤ金刚石膜可以用作ＴａＮ２热敏打印头表面保护层。     

Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond

The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm² V^?1 s^?1 (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.     

Dependence of surface morphology of CVD diamond films on deposition conditions

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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 hy-drogen.The surface morphologies of the obtained diamond films under various de-position conditions have been observed by scanning electron microscope (SEM).The experimental results strongly indicate that the surface morphologies of the re-sulting films have closely related to the deposition conditions,i.e.,reaction pres-sure.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 .     

衬底位置对大面积CVD金刚石薄膜质量的影响

采用石英钟罩式微波等离子体化学气相沉积(MWPCVD)设备制备了大面积金刚石薄膜,结合X射线衍射谱(XRD)、扫描电子显微镜(SEM)和激光喇曼(Raman)谱等实验手段,较系统地研究了衬底位置对金刚石薄膜质量的影响规律.结果表明,在等离子体球内部的空间范围内,距等离子体球中心垂直距离越远衬底上所沉积的金刚石薄膜质量越好;通过调整衬底位置,可明显改善其上不同区域所沉积的金刚石薄膜质量,最后在等离子体球边缘附近可沉积出晶粒均匀一致几乎不舍非晶碳的大面积高质量金刚石薄膜.此研究为进一步改善大面积金刚石薄膜均匀性和薄膜质量提供了一种实用的途径.     

激光诱导等离子体在金刚石表面沉积金属薄膜

介绍了一种利用脉冲准分子激光轰击钛(或镍)靶诱导出等离子体从而在金刚石颗粒表面沉积Ti，Ni等金属保护层的新方法。使用抗压强度测定仪测定并比较了金刚石颗粒表面镀敷金属层前后的抗压强度值，使用金相显微镜观察了金刚石镀膜前后的表面微观状态，并利用x射线衍射仪(XRD)测定了沉积在金刚石颗粒表面金属层的组份。结果表明，利用脉冲准分子激光在金刚石颗粒表面镀Ti后其抗压强度显著增加，而且由于脉冲准分子激光轰击金属靶材后诱导的等离子体能量较高，即使在非高温工作情况下也可在金刚石表面生成TiC膜，这大大提高了金属膜层与金刚石颗粒之间的结合紧密度，这种TiC膜层的形成对于延长金刚石锯片的使用寿命具有重大意义。     

氢原子侵蚀作用的研究

通过热力学计算和动力学分析，研究了热丝ＣＶＤ金刚石薄膜沉积过程中，氢原子对石墨相和金刚石相的侵蚀作用。结果表明；当衬底温度在８２３Ｋ－１２７３Ｋ间变化时，氢原子和石墨相反应的表观活化能小于氢原子和金刚石相反应的表观活化能，这是氢原子更易侵蚀石墨相的原因所在。     

Selective deposition of diamond films

Polycrystalline diamond films have been selectively deposited on a silicon surface. A novel process was developed which exposes a patterned, scratch damaged silicon area, surrounded by SiO₂, to a high pressure microwave plasma of hydrogen containing methane. The hydrogen plasma dissociates the methane injected into the reaction chamber, resulting in diamond deposition, which occurs only on the exposed silicon. Under the process conditions described in this work, some in situ plasma etching of the oxide is observed, resulting in little or no growth of diamond in unwanted areas, and further enhancing the selectivity. A variety of patterns and structures have been fabricated. Raman spectroscopy confirmed the films were diamond.     

脉冲激光沉积类金刚石膜技术

脉冲激光沉积(PLD)技术制备类金刚石(DLC)薄膜存在着金刚石相含量较低、石墨颗粒多、薄膜与衬底附着力差、膜内应力大等技术难题,为此,研究人员研究出了多种技术措施,如通过引入背景气体、超快激光、偏压、磁场以及加热等措施提高了薄膜金刚石相含量;采用金刚石或丙酮靶材、减小单脉冲能量等措施减少了石墨颗粒;采用间歇沉积、真空退火、超快激光等措施减少了膜内应力;合理没计过渡层改善了膜与衬底间的附着力等.这些技术有力地推动了脉冲激光沉积技术的发展.     

金刚石薄膜低压气相生长中衬底表面缺陷的成核理论

在低压气相生长金刚石薄膜过程中,通过在衬底表面引入缺陷,通常是一种行之有效的提高成核密度的方法。但是,至今尚无公论的关于这种缺陷成核机制的详细报导和理论解释。本文在实验观测的基础上,提出了金刚石膜在衬底表面凹陷结构缺陷内成核的理论,并且讨论了该理论对于试图通过控制衬底表面缺陷来控制金刚石膜成核密度等人工微结构设计研究的意义。     

碳纳米管在金刚石薄膜化学沉积上的应用

碳纳米管的端头部位,具有一定的金刚石结构。用于金刚石薄膜气相化学沉积,作为籽晶,可使薄膜沉积的速度加快,结晶的定向性强,生长的温度低等优点。本文探讨了碳纳米管的结构,初步研究了其在金钢石薄膜气相化学沉积上的应用,得到了较好的〈１００〉方向结果的薄膜。     

金刚石镶嵌非晶碳膜表面微尖对场致发射的增强作用

用微波等离子体化学气相沉积设备,在金属钼衬底上沉积出了表面存在大量微尖的金刚石镶嵌非晶碳膜,分别用扫描电子显微镜（ＳＥＭ）、金相显微镜和Ｘ射线衍射谱（ＸＲＤ）及Ｒａｍ ａｎ谱对样品进行了分析测试,并研究了各样品的场致电子发射特性。结果发现：在笔者的实验范围内,金刚石薄膜表面微尖对场致电子发射具有增强作用,且薄膜表面微尖数目越多,场发射电流密度和发射点密度越高,场发射的发射阈值越低。最后建立了一个二次场增强模型对实验结果进行了解释     

Research on the hydrogen terminated single crystal diamond MOSFET with MoO3 dielectric and gold gate metal

The single crystal diamond with maximum width about 10 mm has been grown by using microwave plasma chemical vapor deposition equipment.The quality of the grown diamond was characterized using an X-ray diffractometer.The FWHM of the (004) rocking curve is 37.91 arcsec,which is comparable to the result of the electronic grade single crystal diamond commercially obtained from Element Six Ltd.The hydrogen terminated diamond field effect transistors with Au/MoO3 gates were fabricated based on our CVD diamond and the characteristics of the device were compared with the prototype Al/MoO3 gate.The device with the Au/MoO3 gate shows lower on-resistance and higher gate leakage current.The detailed analysis indicates the presence of aluminum oxide at the Al/MoO3 interface,which has been directly demonstrated by characterizing the interface between Al and MoO3 by X-ray photoelectron spectroscopy.In addition,there should be a surface transfer doping effect of the MoO3 layer on H-diamond even with the atmospheric-adsorbate induced 2DHG preserved after MoO3 deposition.     

金刚石基底上制备(002)AlN薄膜的研究

首先采用微波等离子体化学气相沉积(MPCVD)方法,在O2/H2/CH4混合气体气氛下利用大功率微波在(100)Si片上生长出了异质外延金刚石膜,X-射线衍射(XRD)、拉曼光谱和场发射扫描电子显微镜(FESEM)对薄膜的表征分析结果表明,制备的金刚石膜具有很高的金刚石相纯度,且晶粒排列紧密;继而采用射频磁控反应溅射法,在抛光的金刚石基底上成功制备了高C轴择优取向的氮化铝(AlN)薄膜,研究了不同的溅射气压、靶基距对AlN薄膜制备的影响,XRD检测结果表明,溅射气压低,靶基距短,有利于AlN(002)面择优取向,相反则更有利于AlN薄膜的(103)面和(102)面择优取向;研究了AlN薄膜在以N终止的金刚石基底和纯净金刚石基底两种表面状态上的生长机制,结果发现,以N终止的金刚石基底非常有利于AlN(002)面择优取向生长;从Al-N化学键的形成以及溅射粒子平均自由程的角度,探讨了其对AlN薄膜择优取向的影响。     

Deposition of diamond from alcohol precursors in an electron cyclotron resonance plasma system

Microstructural control is a critical issue in the use of diamond films in a variety of engineering applications. Using a novel, electrostatic-based particle seeding process, we have investigated the deposition of diamond films with varying areal nucleation densities. Depositions were performed at low pressures (1.000 and 1.500 Torr) in a modified electron cyclotron resonance plasma system. Methyl alcohol was the primary diamond precursor species. Scanning electron microscopy and Raman spectroscopy were used to evaluate microstructure and composition characteristics. Comparisons in deposition characteristics were made based on relative nucleation density and gas-phase composition.     

Study of oriented growth of oligofluorene–thiophene films onto aligned vacuum-deposited polytetrafluoroethylene layers

An analysis of a vacuum-deposited fluorene-thiophene-based material 5,5′-Di(9,9′-di-(butyl)-fluorene-2,2′-bithiophene) (DBFBT) onto different substrates, which can act as dielectric gate for organic field-effect transistor is made. Also a new method for preparation of high-quality dielectric thin films made of polytetrafluoroethylene (PTFE) is described. This method includes film formation by means of a special kind of vacuum deposition polymerization (VDP) of PTFE, assisted by electron cloud activation. Rubbing of these layers makes them orienting substrate materials which induce spontaneous ordering of deposited organic semiconductor layers. We investigated structure and morphology of PTFE layers deposited by vacuum process in dependence on deposition parameters: deposition rate, deposition temperature, electron activation energy and activation current. The molecular structure of the PTFE films was investigated by use of infrared spectroscopy. By means of ellipsometry, values of refractive index between 1.33 and 1.36 have been obtained for PTFE films in dependence on deposition conditions. Using the cold friction technique orienting PTFE layers with unidirectional grooves are obtained. We have shown that DBFBT layers growth on top of rubbed PTFE films present a certain alignment suitable for building organic field-effect transistors with better transport parameters.     

异质外延立方氮化硼薄膜的微结构研究

利用离子束辅助沉积技术在金刚石薄膜衬底上制备立方氮化硼薄膜,傅立叶变换红外谱的结果表明,在高度(001)织构金刚石薄膜衬底上沉积的立方氮化硼薄膜是纯的立方相,而在多晶金刚石薄膜衬底上制备的立方氮化硼薄膜中还含少量的六角氮化硼。高分辨透射电镜的分析表明,在金刚石晶粒上异质外延的c-BN直接成核于金刚石衬底,界面没有六角氮化硼过渡层;而在含有大量缺陷的晶粒边界,存在六角氮化硼的成核与生长。     

化学气相沉积光学级金刚石薄膜的研究进展

化学气相沉积（CVD））金刚石薄膜优异的光学性能在近几年得到了广泛的重视,关于它的研究也在近几年取得了较大的突破。综述了CVD金刚石薄膜的光学性能,着重从成核、生长和后期处理三个方面对光学级CVD金刚石薄膜的制备进行了讨论,并对今后的研究作了展望。