Growth and electron field emission of ZnO nanorods on diamond films

Zinc oxide (ZnO) nanorods grown on chemical vapor deposited diamond films by thermal vapor transport method have been investigated. In the initial growth status, the semi-spherical ZnO nuclei were preferably deposited near the growth steps on the terraces and the boundaries of diamond grains. With increasing the growth time, the [0 0 0 1] orientated ZnO nanorods appeared and further covered the whole diamond film. It is found that the size of diamond grains would determine the diameter of ZnO nanorods. The electron field emission properties of the ZnO nanorods/diamond system have been significantly improved with respect to pure diamond film. The feature of the ZnO nanorods grown on diamond films played an important role in further enhancing the electron field emission performances.     

热丝CVD生长金刚石薄膜喇曼散射研究

本文报道热丝化学气相沉积法（ＨＦＣＶＤ）生长金钢石薄膜的喇曼散射结果。选取多种峰型，对金钢石薄膜喇曼谱（１１０－１８００ｃｍ－１）采用最小二乘法进行非线性拟合，得到最佳拟合模型，其计算得到的拟合曲线怀实验谱图符合得较好。该模型揭示，石墨Ｄ峰（１３５５ｃｍ－１）是金刚石薄膜喇曼谱中不可缺少的一个组份，并且结合石墨Ｄ峰和金刚石喇曼的空间相关线型，可以解释金刚石喇曼区特殊峰形的物理机制，拟合参量的进一步     

Simulation of the graphite–diamond transition in an isentropic process

An equation of state for graphite and diamond has been derived in wide density and temperature ranges. A set of equations for the graphite–diamond phase transition has been presented. Hugoniots for graphite and diamond have been calculated. Numerical simulation data for the graphite–diamond transition in the isentropic compression process using a metallic z-pinch with diamond saving have been reported.     

Growth and Characteristics of Freestanding Hemispherical Diamond Films by Microwave Plasma Chemical Vapor Deposition

Freestanding hemispherical diamond films have been fabricated by microwave plasma chemical vapor deposition using graphite and molybdenum （Mo） as substrates. Characterized by Raman spectroscopy and scanning electron microscopy, the crystalline quality of the films deposited on Mo is higher than that on graphite, which is attributed to the difference in intrinsic properties of the two substrates. By decreasing the methane concentration, the diamond films grown on the Mo substrate vary from black to white, and the optical transparency is enhanced. After polishing the growth side, the diamond films show an infrared transmittance of 35-60% in the range 400-4000 cm^- 1.     

Effect of nitrogen addition on hydrogen incorporation in diamond nanorod thin films

The effect of nitrogen addition in the feed gas on the finally incorporated amount of hydrogen in the diamond nanorods (DNRs) thin films has been investigated. The Raman spectroscopy measurements helped to understand the structural and quality changes with increasing nitrogen gas flow rate during CVD deposition. The hydrogen concentration was measured with 3.0 MeV He²⁺ beam using elastic recoil detection analysis technique and it was found that with the addition of nitrogen, the hydrogen concentration was increased. The results of non-Rutherford backscattering spectroscopy (NRBS) used to measure the amount of nitrogen in the DNRs thin films have shown that the incorporated nitrogen is below the detection limit of NRBS technique. Our results suggested that the addition of nitrogen has affected the overall quality of diamond films in two ways; increasing the thickness of diamond films by increasing the non-diamond carbon content and increasing the hydrogen impurity incorporation. The role of nitrogen additive on diamond growth and hydrogen incorporation is discussed.     

Laser Induced Damage in CVD Diamond Films

ＬａｓｅｒＩｎｄｕｃｅｄＤａｍａｇｅｉｎＣＶＤＤｉａｍｏｎｄＦｉｌｍｓＱＩＵＨｏｎｇＦＡＮＺｈｅｎｇｘｉｕ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈａｎｉｃｓ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｐ．Ｏ．...     

Copper-induced diamond formation in amorphous carbon

Diamond formation in hydrogenated amorphous-carbon films containing ultradisperse copper has been studied by measuring IR absorption at two-phonon diamond frequencies. The anomalously high two-phonon absorption observed in the experiments has permitted improving the sensitivity of the method. Mechanisms of the two-phonon absorption enhancement are discussed in terms of the theory of a medium containing nanosized copper-doped graphite fragments. It is shown that the observed enhancement of two-phonon absorption is caused by electrical induction of the local fields induced by irradiation in diamond nanocrystals acting on adjoining copper-doped graphite fragments. Fiz. Tverd. Tela (St. Petersburg) 41, 1863–1866 (October 1999)     

高气压MPCVD沉积金刚石的光谱研究

采用微波等离子体化学气相沉积方法(microwave plasma chemical vapor deposition, MPCVD)在高沉积气压(34.5 kPa)下制备多晶金刚石,利用发射光谱(optical emission spectroscopy, OES)在线诊断了CH₄/H₂/O₂等离子体内基团的谱线强度及其空间分布,并利用拉曼(Raman)光谱评价了不同O₂体积分数下沉积出的金刚石膜质量,研究了金刚石膜质量的均匀性分布问题。结果表明：随着O₂体积分数的增加,C₂, CH及H_α基团的谱线强度均呈下降的趋势,而C₂,CH与H_α谱线强度比值也随之下降,表明增加O₂体积分数不仅导致等离子体中碳源基团的绝对浓度下降,而且碳源基团相对于氢原子的相对浓度也降低,使得金刚石的沉积速率下降而沉积质量提高。此外,具有刻蚀作用的OH基团的谱线强度却随着O₂体积分数的增加而上升,这也有利于降低金刚石膜中非晶碳的含量。光谱空间诊断发现高沉积气压下等离子体内基团分布不均匀,特别是中心区域C₂基团聚集造成该区域内非晶碳含量增加,最终导致金刚石膜质量分布的不均匀。     

Effects of N2 addition on nanocrystalline diamond films by HFCVD in Ar/CH4 gas mixture

Nanocrystalline diamond (NCD) films were grown on silicon substrates by hot filament chemical vapor deposition in Ar/N₂/CH₄ gas mixtures. The effects of seeding process prior to deposition, the total gas pressure, and concentration of nitrogen on the grain size, morphology and bonding nature in HFCVD technique were investigated. The results indicated that a low total gas pressure is favorable for nanosized diamond crystallites. Films micrograph obtained from scanning electron microscopy showed diamond nanograins elongated with the addition of nitrogen in the plasma. Crystal structure investigations were carried out by X-ray diffraction measurements for deposited films. An increase in the size of crystallite is also observed from XRD measurements in NCD film when nitrogen was added in plasma. From Raman spectra, it was observed that the relative intensity of G peak increases indicating more graphite content after nitrogen added in the plasma. The effects of the nitrogen incorporation in nanocrystalline films in HFCVD are discussed.     

B离子注入引起的金刚石薄膜体积膨胀现象

离子注入是获得金刚石N型或P型导电材料的有效途径之一。然而,离子注入对金刚石的晶格结构有破坏作用,造成金刚石薄膜体积的膨胀。本文对B离子注入合成Ib型金刚石薄膜后体积膨胀现象进行了研究,分析了引起体积膨胀的可能因素及原因。     

Cu-MgF2复合纳米金属陶瓷薄膜的电导特性研究

用射频磁控共溅射法制备了Cu体积分数分别为10%，15%，20%和30%的Cu-MgF₂复 合金属陶 瓷薄膜.用x射线衍射、x射线光电子能谱和变温四引线技术对薄膜的微结构、组分及电导特 性进行了测试分析.微结构分析表明：制备的Cu-MgF₂复合薄膜由fcc-Cu晶态纳 米微粒镶嵌 于主要为非晶态的MgF₂陶瓷基体中构成，Cu晶粒的平均晶粒尺寸随组分增加从1 1.9nm增 至17.8nm.50—300K温度范围内的电导测试结果表明：当Cu体积 关键词： 2复合纳米金属陶瓷膜')" href="#">Cu-MgF₂复合纳米金属陶瓷膜 微结构 组分 电导特性 激活能 渗透阈     

Structural and compositional analyses of nanocrystalline diamond/β-SiC composite films

Nanocrystalline diamond/β-SiC composite films are synthesized by microwave plasma chemical vapor deposition using a gas mixture of H₂, CH₄, and tetramethylsilane (Si(CH₃)₄, TMS) in a single process step. Structural and compositional analyses revealed that the films consist of a mixture of diamond and β-SiC nanocrystalline phases in a desired volume fraction combinatorial form. Transmission electron microscopy analysis confirmed the X-ray diffraction results and showed that the major diffraction lines corresponded to a two-component nanocrystalline composite film. Infrared spectroscopic analysis showed that the content of β-SiC in the films can be increased by increasing the TMS concentration. This correlated very well with electron probe microanalysis and Rutherford backscattering analysis that showed an almost linear correspondence of β-SiC content in the films with the TMS concentration in the gas phase. The phase purity of the diamond crystallites decreased with increase in the β-SiC content in the films, as shown by micro Raman scattering studies. Smooth surface morphologies are measured for these films by using atomic force microscopy; the root mean square roughness was 12 ± 1 nm. The β-SiC volume fraction (vol. %) was identified as an important compositional factor to determine any mechanical and frictional properties of these films. PACS 68.55.-a; 68.55.Nq; 68.60.-p     

Raman scattering spectra and electrical conductivity of thin silicon films with a mixed amorphous-nanocrystalline phase composition: Determination of the nanocrystalline volume fraction

Raman spectra and electrical conductivity of thin films of hydrogenated silicon with mixed amorphous-nanocrystalline phase composition have been studied. It is shown that interpretation of experimental data in terms of percolation theory permits one to determine the integrated Raman-scattering cross-section ratio of the nanocrystalline to amorphous phase and to obtain a quantitative estimate of the volume fraction of each phase. Fiz. Tverd. Tela (St. Petersburg) 39, 1348–1353 (August 1997)     

Enhanced diamond nucleation on copper substrates by graphite seeding and CO2 laser irradiation

Diamond nucleation on copper (Cu) substrates was investigated by graphite seeding and CO₂ laser irradiation at initial stages of the combustion-flame deposition. A graphite aerosol spray was used to generate a thin layer of graphite powders (less than 1 μm) on Cu substrates. The graphite-seeded Cu substrates were then heated by a continuous CO₂ laser to about 750 °C within 1 min. It was found that diamond nucleation density after this treatment was more than three times as much as that on the virgin Cu substrates. As a consequence, diamond films up to 4 μm were obtained in 5 min. The enhancement of diamond nucleation on the graphite-seeded Cu substrates was attributed to the formation of defects and edges during the etching of the seeding graphite layers by the OH radicals in the flame. The defects and edges served as nucleation sites for diamond formation. The function of the CO₂ laser was to rapidly heat the deposition areas to create a favorable temperature for diamond nucleation and growth.     

Coherent Phonon-Mode Excitation in Submicron Single-Crystal Diamond Films with a Graphitized Layer Built-In

We report the first experimental observation of high-efficient phonon-mode coherent excitation using stimulated low-frequency Raman scattering (SLFRS) in submicron diamond{graphite{diamond heterostructure films with an ion-beam-induced graphitized layer. We show that the SLFRS process in submicron diamond heterostructures has a frequency shift in the gigahertz range and estimate experimentally the SLFRS conversion efficiency and threshold.     

高温高压下碳的状态方程及相变理论研究

 研究了高温高压下三相碳（石墨、金刚石、液相碳）的状态方程，包括高压下石墨到金刚石的固-固相变以及高温下石墨和金刚石的熔解曲线。计算所得到的金刚石熔解曲线具有正的斜率，石墨-金刚石-液相三相点为4 400 K，14 GPa左右。     

Investigation of atomic structures of diamond-like amorphous carbon by electron energy loss spectroscopy

Research into amorphous carbon films has been developed to such an extent that the film property can be fine tuned to mimic that of the crystalline counterparts, be it diamond, graphite, or even fullerene-like. This flexibility makes such films ideal for a wide range of applications from anti-abrasive window coating to lubricating layers on the surface of magnetic hard-disk. Not only are their mechanical properties interesting, electrically the diamond-like amorphous carbon films are also easier to dope than crystalline diamond, making them potentially a better alternative to amorphous silicon for photovoltaic devices. We will show that electron energy loss spectroscopy, in particular the carbon 1s core absorption spectroscopy, has been instrumental in revealing the nature of the bonding between carbon atoms. Such information allows microstructure models to be developed for proper understanding of the observed properties and providing scientific basis for future improvement.     

氦气对MPCVD沉积金刚石的影响

为了确定添加氦气对微波等离子体化学气相沉积(MPCVD)金刚石膜的影响,采用发射光谱法(OES)在线诊断了CH₄-H₂-He等离子体的发射光谱特性,研究了He对等离子体内基团空间分布的影响;并利用扫描电子显微镜(SEM)和拉曼(Raman)光谱对不同He体积分数下沉积出的金刚石膜进行了表征。结果表明：随着He体积分数的增加,等离子体内H_α, H_β, H_γ, CH和C₂基团的谱线强度均呈上升趋势,其中H_α基团的谱线强度增加最大。光谱空间诊断发现He的加入导致等离子体中各基团的空间分布均匀性变差,造成沉积出的金刚石膜厚度极不均匀。沉积速率测试表明,He的加入导致碳源基团相对浓度增加,有利于提高薄膜的沉积速率,当He体积分数由0 vol.%增加至4.7 vol.%时,沉积速率提高了24%。SEM测试结果表明,随着He体积分数的增加,金刚石膜表面形貌由(111)晶面取向向晶面取向混杂转变,孪晶生长明显。高He(4.7 vol.%)体积分数下由于C₂基团的相对浓度较高,导致二次形核密度增加。此外,由于基片台受到等离子体的刻蚀和溅射作用,导致薄膜沉积过程中引入了金属杂质原子。二次形核和杂质原子的存在使得孪晶大量的产生,薄膜呈现出压应力。     

IR spectra of small molecules adsorbed on carbon films. Adsorption potentials and spectral shifts

IR spectra of CO, NO and CH₃F adsorbed on graphite-like and diamond powder films were studied at low temperatures. The graphite-like films were prepared by laser evaporation of graphite in He atmosphere. The diamond films were obtained by sedimentation of fine diamond particles from a suspension. In a11 cases physical adsorption was observed. The spectrum of adsorbed NO showed clearly the presence of dimers. For CO, the adsorption potential and the shift in frequency from the gas phase were calculated for both adsorbents, and compared with the experimental values.     

Domain structure of cellulose triacetate

The topology of the surface of thin films obtained from cellulose triacetate solutions has been studied using electron microscopy. The domain structure of the physical network of macromolecules (percolation cluster) with the maximum size L ≈ 30 nm of regions with a local orientational order has been established. With an increase in the volume fraction Ω of the cluster to the critical value Ω = 0.91, repacking of domains takes place, which is connected with a decrease in the parameter Ω, L doubling bifurcation of the size L, and formation of regions of long-range orientational order: the mesophase of the polymer.