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.

Effect of Gas Sources on the Deposition of Nano-Crystalline Diamond Films Prepared by Microwave Plasma Enhanced Chemical Vapor Deposition

Nano-crystalline diamond （NCD） films were deposited on silicon substrates by a microwave plasma enhanced chemical vapor deposition （MPCVD） reactor in C2H5OH/H2 and CH4/H2/O2 systems, respectively, with a constant ratio of carbon/hydrogen/oxygen. By means of atomic force microscopy （AFM） and X-ray diffraction （XRD）, it was shown that the NCD films deposited in the C2H5OH/H2 system possesses more uniform surface than that deposited in the CH4/H2/O2 system. Results from micro-Raman spectroscopy revealed that the quality of the NCD films was different even though the plasmas in the two systems contain exactly the same proportion of elements. In order to explain this phenomenon, the bond energy of forming OH groups, energy distraction in plasma and the deposition process of NCD films were studied. The experimental results and discussion indicate that for a same ratio of carbon/hydrogen/oxygen, the C2H5OH/H2 plasma was beneficial to deposit high quality NCD films with smaller average grain size and lower surface roughness.

Microscopic mechanical characteristics analysis of ultranano-crystalline diamond films

The microscopic mechanical characteristics of ultranano-crystalline diamond films which were prepared in four different atmospheres were investigated for the applications in microelectron-mechanical system（MEMS）.The loading-unloading curves and the change of modulus and hardness of samples along with depth were achieved through nanoindenter.The results show that the films which are made in atmosphere without Ar have the highest recovery of elasticity,hardness（72.9 GPa） and elastic modulus（693.7 GPa） among the samples.Meanwhile,samples fabricated at a low Ar content have higher hardness and modulus.All the results above demonstrate that atmosphere without Ar or low Ar content leads to better mechanical properties of nanodiamond films that are the candidates for applications in MEMS.

Enhancement and Optimization of ATO Nano-crystalline Films Properties by the Addition of Acetylacetone as Modifier in the Sol-gel Process

Sb-doped Sn O2(ATO) thin films have been prepared using the spin coating method by selecting the proper amount of acetylacetone as solution modifier. All ATO powders and films exhibited the cassiterite rutile-like structure in a crystal size below 10 nm under all the experimental conditions and a nonpreviously reported crystal structure was observed at high acetylacetone loads. The acetylacetone molar ratio influenced notably the optical and electrical properties of ATO films. When prepared at an acetylacetone molar ratio of 4, ATO films exhibited optical transparencies above 90% in the visible region and above 40% in the UV region for thicknesses of 100 and 300 nm. Films in a thickness of 100 nm and at an annealing temperature of 650 ℃ accounted for a high transparency of 97% in the visible wavelength. Films prepared at an acetylacetone molar ratio of 4 exhibited an electric resistivity of 1.33×10-3 Ω·cm at an annealing temperature of 650 ℃. The optimal Sb content for ATO films was found to be 8 at%. The relationships among the properties of starting solutions, the experimental parameters, and properties of ATO films are discussed.

Deposition and Boron Doping of Nano-Crystalline Diamond Thin Films on Poly-Crystalline Diamond Thick Films

Boron-doped nano-crystalline diamond （NCD） thin films have been successfully deposited on well-polished poly-crystalline diamond （PCD） thick films in a microwave plasma enhanced chemical vapor deposition （MPCVD） reactor for the first time. Different surface pretreatment techniques are carried out under different gas conditions （CH4, H2, Ar, and CH4/H2） to eliminate the effect of grain boundaries on the growth of a smooth NCD intrinsic layer. Well doped NCD films have been fabricated in CH4/H2/B2H6 plasma by varying the atomic ratio of B/C and the substrate temperature. Atomic force microscopy （AFM） results show that pretreatment in pure CH4 plasma at 1000℃ is most effective for NCD growth, while hydrogen containing plasma is harmful to the surface smoothness of NCD thin fihns. Doping research indicates that the optimum parameters for the boron-doping of high-quality NCD thin films are B/C=300 ppm （10-6） and 800℃.

Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films

In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth processes.The transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow rate.The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate.The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture structure.There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.

Synthesis of Nano-Crystalline Diamond Film in Hot Filament Chemical Vapour Deposition by Adding Ar

Nano-crystalline diamond films are successfully deposited on silicon substrates via the hot filament chemical vapour deposition process using a CH_(4)/H_(2)/Ar gas mixture.The as-grown films are analysed by using field emission scanning electron microscopy,micro-Raman spectroscopy and x-ray diffraction.These results show that the films consist of nano-diamond grains with sizes ranging from 10 to 100 nm,and argon is an important element in the formation of nano-crystalline diamonds.

PREPARATION OF NANO-CRYSTALLINE Fe-Cu THIN FILMS AND THEIR MAGNETIC PROPERTIES

Fe-Cu thin films of 0.2 mum in thickness with different Cu contents wereprepared by using r.f. magnetron sputtering onto glass substrate. The effect of sputteringparameters, including Ar gas pressure and input rf power, on the structure and magnetic propertieswas investigated. It was found that when the power is lower than 70W, the structure of the filmsremained single bcc-Fe phase with Cu solubility of up to 50at. percent. TEM observations for thebcc-Fe phase showed that the grain size was in the nanometer range of less than 20nm. The coercivityof Fe- Cu films was largely affected by not only Ar gas pressure but also rf power, and reachedabout 2.5Oe in the pressure of 0.67-6.67Pa and in the power of less than 100W. In addition,saturation magnetization, with Cu content less than 60at. percent, was about proportional to thecontent of bcc-Fe. When Cu content was at 60at. percent, however, saturation magnetization was muchsmaller than its calculation value.

Preparation of Nano-Crystalline Diamond Films on Poly-Crystalline Diamond Thick Films by Microwave Plasma Enhanced Chemical Vapor Deposition

Nano-crystalline diamond （NCD） films were prepared on poly-crystalline diamond （PCD） thick flims by the microwave plasma enhanced chemical vapor deposition （MPCVD） method. Free standing PCD thick film （50 mm in diameter） with a thickness of 413 μm was deposited in CHn/H2 plasma. It was then abraded for 2 hours and finally cut into pieces in a size of 10×10 mm^2 by pulse laser. NCD fihns were deposited on the thick film substrates by introducing a micro-crystalline diamond （MCD） interlayer. Results showed that a higher carbon concentration （5%） and a lower substrate temperature （650℃） were feasible to obtain a highly smooth interlayer, and the appropriate addition of oxygen （2%） into the gas mixture was conducive to obtaining a smooth nano-crystalline diamond film with a tiny grain size.

Brightness of Blue/Violet Luminescent Nano-Crystalline AZO and IZO Thin Films with Effect of Layer Number:For High Optical Performance

From different reports, it （AZO） and indium-doped including usage areas. We nanocrystalline films with is realized that there is a need to consider all sides of aluminum-doped zinc oxide zinc oxide （IZO） thin films with their optical, luminescence and surface properties establish an assessment to carry out further information to summarize AZO and IZO impact of the layer number.

Preparation of Nano-crystalline Tungsten Carbide Thin Film by Magnetron Sputtering and Their Electrocatalytic Property for PNP Reduction

Nano-crystalline tungsten carbide thin films were deposited on Ni substrates by magnetron sputtering using WC as target material. The crystal structure and morphology of the thin films were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM） Electrochemical investigations showed that the electrode of the thin film exhibited higher electrocatalytic activity in the reaction of p-nitrophenol （PNP） reduction. FT-IR analysis indicated that p-aminophenol （PAP） was synthesized after two step reduction of PNP on nano-crystalline tungsten carbide thin film electrode.

Preparation of Nano-Crystalline ZnO Thin Films

Zinc oxide (ZnO) thin films were identified as very suitable piezoelectric material for SAW on the basis of its relatively high electromechanical coupling coefficient,as well as high resistivity for low insertion loss and little distortion in the frequency.In this paper ZnO thin films were deposited on Si(100) substrate covered with SiO_2 using a reactive DC magnetic sputtering system from a zinc target.The effects of various deposition parameters on structural and performances have been investigated through experiments.Theoretical and experimental results are also discussed in this paper.XRD showed that the prepared ZnO films had strongly c-axis preferred-orientation.The composition of the film was also determined through high-resolution photoelectron spectroscopy (XPS).AFM showed that the films had smooth surface and that the crystallite sizes of deposited films were in the range 30 nm～50 nm.The above results showed that the films deposited by magnetic sputtering met the demands for surface acoustic wave (SAW) devices.

Hexagonal Nano-Crystalline BCN Films Grown on Si (100) Substrate Studied by X-Ray Absorption Spectroscopy

Hexagonal nano-crystalline boron carbonitride (h-BCN) films grown on Si (100) substrate have been precisely investigated. The films were synthesized by radio frequency plasma enhanced chemical vapor deposition using tris-dimethylamino borane as a single-source molecular precursor. The deposition was performed by setting RF power at 400 - 800 W. The reaction pressure was at 2.6 Pa and the substrate temperature was recorded at 700°C - 800°C. Formation of the nano-crystalline h-BCN compound has been confirmed by X-ray diffraction analysis. The diffraction peaks at 26.3° together with a small unknown peak at 29.2° were elucidated due to the formation of an h-BCN structure. The films composed of B, C, and N atoms with different B-N, B-C, C-N chemical bonds in forming the sp2-BCN atomic configuration studied by X-ray photoelectron spectroscopy. Orientation and local structures of the h-BCN hybrid were studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The dominant presence of p* and s* resonance peaks of the sp2-hybrid orbitals in the B K-edge NEXAFS spectra revealed the formation of the sp2-BCN configuration around B atoms like-BN3 in h-BN. The orientation was suggested on the basis of the polarization dependence of B K-edge and N K-edge of the NEXAFS spectra.

Plasma Processing of Boron-Doped Nano-Crystalline Diamond Thin Film Fabricated on Poly-Crystalline Diamond Thick Film

Plasma treatments of boron-doped nano-crystalline diamond （NCD） thin films were carried out in order to improve their electrical properties of the films. Boron-doped NCD thin films were fabricated on well polished poly-crystalline diamond （PCD） thick films in a microwave plasma enhanced chemical vapor deposition （MPCVD） reactor, then they were processed in methane, ar- gon, hydrogen and B2H~ （0.1% diluted by H~） plasmas, respectively. Scanning electron microscopy （SEM） and atomic force microscope （AFM） results show that the surface morphology changed lit- tle during the 10 min treatment. Secondary ion mass spectroscopy （SIMS） results indicate that B2H6 plasma was efficient for increasing boron concentration in NCD films, while the carrier anal- yses demonstrates that CH4 plasma processing was effective to activate the dopants and resulted in good electrical properties.

Preparation and characterization of nano-crystalline diamond films on glass substrate

Adherent nano diamond films were successfully deposited on glass substrate bymicrowave plasma assisted CVD method in H_2-CH_4 and Ar-CH_4 environment. Raman, AFM (Atomic ForceMicroscope), TEM (Transmission Electron Microscope), FTIR, and Nano Indentation techniques were usedfor characterization of the obtained nano diamond films. It was found that the average grain sizewas less than 100 nm with a surface roughness value as low as 2 nm. The nano diamond films werefound to have excellent transparency in visible and IR spectrum range, and were as hard as naturaldiamond. Experimental results were presented. Mechanisms for nano diamond film deposition werediscussed.

Electrical Properties of Lead Zirconate Titanate Thick Film Containing Micro-and Nano-Crystalline Particles

We report the ferroelectric,dielectric and piezoelectric properties of a dense and crack-free lead zirconate titanate (Pb(Zro.52 Tio.48)O3,PZT) thick film containing micro- and nano-crystalline particles. The results show that these electrical properties are dependent strongly on the annealing temperature and film thickness. For the different-annealing-temperature and different-thickness films,the higher-annealing-temperature thicker ones show the larger remnant polarization and smaller coercive field. The dielectric results show that relative dielectric constant achieves the largest value at annealing temperature of 700℃,and increases with the increasing film thickness.For the piezoelectric properties,the longitudinal piezoelectric coefficient increases linearly with the film thickness increasing and the 4-μm-thick PZT film shows the largest value of about 200.65 pC/N.Therefore,the PZT thick films present good electric properties and enlarged potential in MEMS applications.

Synthesis of Nano-crystalline Diamond Films

We have deposited nano-crystalline diamond films in a routine hot filament chemical vapor deposition system,using CH_(4)/H_(2) gas mixture.Wfe used various measurements such as Reid emission scanning electron microscopy,micro-Raman spectroscopy,x-ray photoelectron spectroscopy,and transmission electron microscopy for characterization.The result show that the films consist of a crystalline diamond phase with small grain sizes ranging from 20 to 100nm.

Ellipsometric analysis and optical absorption characterization of nano-crystalline diamond film

A nano-crystalline diamond (NCD) film with a smooth surface was successfully deposited on silicon by a hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscopy (SEM), atomic force microscopy (AFM), RAMAN scattering spectra, as well as spectroscopic ellipsometry were employed to characterize the as-grown film. By fitting the spectroscopic ellipsometric data in the energy range of 0.75?1.50 eV with a three-layer model, Si|diamond+non-diamond|diamond+ non-diamond+void|air, the optical constants are obtained. The refractive index of the NCD film varies little from 2.361 to 2.366 and the extinction coefficient is of the order of 10?2. According to the optical transmittance and absorption coefficient in the wavelength range from 200 to 1 100 nm, the optical gap of the film is estimated to be 4.3 eV by a direct optical transition mechanics.

PREPARING NANO-CRYSTALLINE La DOPED WC/Co POWDER BY HIGH ENERGY BALL MILLING

The La doped WC/Co powder was prepared by high energy ball milling. The changes of crystal structure, micrograph and defect of the powder were investigated by means of XRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differential thermal analysis). The results show that adding trace La element into carbides is effective to minish the grain size of WC/Co powder. The La doped carbides powder with grain size of 30nm can be obtained after 10h ball milling. The XRD peak of Co phase disappeared after 20h ball milling, which indicated solid solution (or secondary solid solution) of Co phase in WC phase. The La doped powder with grain size of 10nm is obtained after 30h ball milling. A peak of heat release at the temperature of 470℃ was emerged in DTA curve within the range of heating temperature, which showed that the crystal structure relaxation of the powder appeared in the process of high energy ball milling. After consolidated the La doped WC/Co alloy by high energy ball milling exhibits ultra-fine grain sizes and better mechanical properties.

Synthesis and Characterization of Storage Energy Materials Prepared from Nano-crystalline Cellulose/Polyethylene Glycol

This paper gives a brief report of the synthesis of a new kind of solid-solid phase change materials （SSPCMs）, nano-crystalline cellulose/polyethylene glycol （NCC/PEG）. These PCMs have very high ability for energy storage, and their enthalpies reach 103.8 J/g. They are composed of two parts, PEG as functional branches for energy storage, and NCC as skeleton. The flexible polymer PEG was grafted onto the surface of rigid powder of NCC by covalent bonds. The results of DSC, FT-IR were briefly introduced, and some comments were also given.