chemical vapor deposition of ceramics

... conclusion, by chemical vapor deposition of silane, the large-scale SiNWs were grown under the catalysis of Fe particles at the lower temperature – 450 °C These nanowires have a diameter of 50–70 nm ... al / Chemical Physics Letters 411 (2005) 198–202 not only have a size-confined effect on the growth of SiNWs, but also facilitate the pyrolysis and deposition of silane on iron and growth of the ... fourier transform of the outer layer of the triangle (indicated by arrow) depicting lattice spacing of Si(1 1) of 0.31 nm, Si(2 1) of 0.22 nm and Si(2 0) of 0.38 nm, respectively, the bottom-right...

Ngày tải lên: 16/03/2014, 15:06

... in the results and are coated by plenty of amorphous carbons Conclusions A temperature window of SWCNTs growth by catalytic chemical vapor deposition of CH4 over Mo-Fe/MgO catalyst has been studied ... the influence of growth temperature on the purity of prepared tube samples, we give the curve (Fig 4) showing the dependence of ID/IG on the growth temperature From Fig 4, two kinds of ID/IG distributions ... the self-decomposition of CH4 The temperature window of SWCNTs efficiently growth is between 800 and 950 °C, and the optimum growth temperature is about 900 °C Fig Influence of growth temperature...

Ngày tải lên: 22/06/2014, 00:20

... TEM image of the as-grown SiNWs Inset is a SAED pattern; (b) HREM image of a typical SiNW 50 Y.F Zhang et al / Chemical Physics Letters 330 (2000) 48±52 After the deposition, the color of the nanowires ... HRTEM image of a nanowire consisting of a crystalline Si core and a sheath of multi-walled CNTs; (b) a nanowire with a part of the core transformed into b-SiC and coated with a sheath of CNTs b-SiC ... image of the nanowires with carbon deposition at $1300°C and the higher magni®cation image of a part of the sample in the upper image feather-like carbon sheets sprouting from the surface of the...

Ngày tải lên: 16/03/2014, 15:04

... orientation of the evolving Si-NWs In this study, we investigate the morphological evolution of Si-NWs on Si substrates grown by nanoscale Au–Si island-catalyzed rapid thermal chemical vapor deposition ... bright tips of the NWs seem to be Au–Si droplets in Fig 1(d) The diameters of the NWs are similar to those of the Au–Si droplets The existence of a critical Au film thickness for initiation of NW nucleation ... transformation of the liquid into Au–Si alloy droplet structures, whose shape is determined by minimization of the surface and interface energy of the liquid/substrate Also, the composition of the Au–Si...

Ngày tải lên: 16/03/2014, 15:15

... 200-nm-thick silicon on insulator thin films [8–10] Simulation of the emission spectrum of an ehp by a convolution product of the density of states of the carriers affected by the Fermi–Dirac distribution ... of the passivated SiNWs PL as a function of pump power When pump power increases, the 1.08 eV contribution progressively dominates the spectrum (Fig 3a) And the plot (Fig 3b) of the maximum of ... take into account the dynamics of the system, and gives mean values of the density and the temperature (/nS$5.1018 cmÀ3, /TS$86 K) of the system In any case, the shape of the simulation is in good...

Ngày tải lên: 16/03/2014, 15:19

... diameter of the nanotubes can also be tuned by control of the diameter of template fiber by simply adjusting the physical properties of polymer solution, this usually begeted changes of the solution ... average outer diameter of the nanotubes is around 170 nm and the surface of nanotubes is smooth The tubular structures are clearly shown in Fig 3c The SEM image of a crosssection of nanotubes reveals ... high-magnification SEM images of aligned SiOx nanotubes c SEM image of a cross-section of SiOx nanotubes structure Figure 4a and b show, respectively, the TEM images of aligned nanotubes and an...

Ngày tải lên: 22/06/2014, 00:20

... In this study, the effects of H2 flow rate during plasma pretreatment on the synthesis of MWCNTs on a Ni/TaN/Si substrate by using a microwave plasma chemical vapor deposition (MPCVD) system are ... parameter The synthesis of MWCNTs by CVD often involves three main steps: (1) decomposition of hydrocarbon gas at the surface of the catalyst nanoparticles; (2) diffusion of resultant carbon atom ... carbon atoms The change of elastic energy and surface energy of the carbon layer caused the radius of curvature of the Ni catalyst particle to become small The rising gradient of the surface energy,...

Ngày tải lên: 22/06/2014, 01:20

... Thus, TMGa has a vapor pressure of 65.4 Torr at 0°C while triethyl Ga (TEGa) has a vapor pressure of only 4.4 Torr at the much higher temperature of 20°C.[24] The lower vapor pressure of TEGa can ... proper name of the technique One still finds MOCVD referred to as organometallic chemical vapor deposition (OMCVD), metal-organic vapor phase epitaxy (MOVPE—the name used by one of the most important ... condensation of the chemical on the walls of the tubing that lead to the reaction chamber This favors the use of high vapor pressure sources Of course, if the most desirable source has a low vapor pressure,...

Ngày tải lên: 14/02/2014, 03:20

... electrodes of TFTs were next realized by the electron-beam evaporation of Ti/Pt/Au (20/30/150 nm) metal layers and the lift-off process The TFT fabrication process was completed with the opening of vias ... same as those of the samples used for fabricating TFTs 3.4.1 XRD and PL The XRD spectra of the as-grown and N2 O-treated ZnO samples are shown in Fig The intensity of the (0002) peak of the N2 O-treated ... by the use of an insulating glass substrate Because of this, all spectra were calibrated using C 1s at 284.6 eV as a reference Figure shows the XPS spectra of O 1s on the surface of as-grown...

Ngày tải lên: 05/03/2014, 21:20

... observe the peak position of E2 modes lies at 437.4 cmÀ1 The slight discrepancy of the position of the E2 mode of ZnO films and powder shows that our samples are almost free of stress We find the second ... Raman spectra of ZnO films and ZnO powder (a) Raman spectrum of non-doped ZnO film; (b) Raman spectrum of N-doped ZnO film; (c) Raman spectrum of ZnO powder 128 X Wang et al / Journal of Crystal Growth ... of A1(LO) mode and the observation of E2 mode and A1(LO) mode coinciding with the prediction of group theory imply the better crystal quality of nitrogen doped ZnO film In the Raman spectrum of...

Ngày tải lên: 05/03/2014, 21:20

... Table 2.1 Typical deposition parameters for deposition of oxide layers in the present work Deposition temperature, °C 600 - 750 Temperature of flash evaporator, °C 230 - 240 Deposition pressure, ... thin film of the required composition In Fig 2.3 the real view of key components of the MOCVD deposition system used in this work is shown Fig 2.3 MOCVD reactor used for the deposition of oxide ... 89 3.3 Deposition of epitaxial SrRuO3 films 92 3.3.1 Control of SrRuO3 film composition 92 3.3.2 Surface morphology of SrRuO3 films in dependence of deposition temperature,...

Ngày tải lên: 14/03/2014, 19:20

... measurement The presence of trace of P confirms our previous 544 M Lu et al / Chemical Physics Letters 374 (2003) 542–547 Fig (a) TEM image of a single SiNW, (b) SAED pattern of the single SiNW, the ... are the cubic indices of the diffractive spots Fig (a) SEM image of SiNWs arrays, (b) TEM image of SiNWs arrays, (c) EDS spectrum of SiNWs arrays finding that anion ions of anodizing electrolytes ... large of Lewis acid nature of surface sites in amorphous and transition alumina and these sites have the intrinsic catalytic activity of transition alumina in front of the decomposition of silane...

Ngày tải lên: 16/03/2014, 15:08

... following conditions: oxygen flow rate of 20 sccm, operating pressure of 0.5 Torr, microwave power of 600 W, process duration of 5–35 s, and average sample temperature of about 30 °C It was demonstrated ... ethanol molecules The conductance of the sensors adjusts itself when they are exposed to ethanol gas Experimental In this work, microwave plasma enhanced chemical vapor deposition (MPECVD) was used ... illustrates the sensitivity of various surface modification durations As we can see, the sensitivity of the specimen with 20 s of oxygen plasma treatment is superior to that of the other specimens,...

Ngày tải lên: 20/03/2014, 13:06

... variation of the properties of tungsten oxide highly depended on the OGC of the gas mixture Slight rise of OGC from 0.3% to 0.7% in the mixture gas during deposition resulted in large change of the ... (a) N(E) Fig XPS plot of (a) low OGC and (b) high OGC WOx proved the assumption of deposition of atomic tungsten The two upper binding energy peaks exhibited the presence of oxygen modified W4f5/2 ... the trend of growth In summary, the stoichiometry phase evolution of tungsten oxide highly depended on the variation of OGC in mixture gases during deposition Following an increase of OGC, the...

Ngày tải lên: 22/06/2014, 18:20

... resulting valence band offset is only about 0.1 eV In this paper, we present a photoluminescence (PL) study on strained Si/Si0.66Ge0.34 CQWs grown by ultra high vacuum chemical vapor deposition (UHV-CVD) ... 151 (W) and barrier (B), and DEc and DEv are the band offsets of the conduction and valence bands, respectively Hence, out of the total FWHM of 40 meV, 13.1 meV is contributed by the interface ... DEv,1, DEv,2 and DEv,3 represent the band energy offsets of the light, heavy and split-off band at the valence band, respectively The energy splitting of the conduction band is given by the following...

Ngày tải lên: 22/06/2014, 22:20

... beaker in such a way that an approximately mm thick layer of deposition bath separates the substrates each other and the wall of the bath 25 ml of 1M CS(NH2)2 then is poured into the mixtures Finally, ... VNU Journal of Science, Mathematics - Physics 24 (2008) 119-123 (a) (b) Fig SEM images of CdS thin films prepared in the bath with ml of 1M CdSO4 solution for 9h (a) and with 25 ml of 1M CdSO4 ... powdered precipitation After deposition, the substrate were removed from the chemical bath, cleaned thoroughly in distilled water and dried in the air at room temperature The deposition time is chosen...

Ngày tải lên: 14/03/2014, 13:20

... number of books are available that deal with the chemical processing aspect of ceramic materials, but most of them are conference proceedings This revised edition of Chemical Processing of Ceramics ... questions are difficult, but the creativity of our responses may determine the quality of life for the new age This new edition of Chemical Processing of Ceramics offers a scientific and technological ... Composites, Peter Morgan 28 Chemical Processing of Ceramics: Second Edition, Burtrand Lee and Sridhar Komarneni © 2005 by Taylor & Francis Group, LLC Chemical Processing of Ceramics Second Edition...

Ngày tải lên: 02/04/2014, 15:39

... approach involving bias-enhanced nucleation (BEN) [14] of plasma-enhanced chemical vapor deposited (PECVD) diamond films To ensure the suitability of diamond films in a cooling design, thermal conductance ... PARAMETERS FOR THE GROWTH OF PECVD DIAMOND FILMS a set of 1-D heat conduction equations [15], [24] Details of the derivation process have been described in [15] The solution of in the gas can be the ... algorithm where trial values of the unknown thermal properties are used to calculate the phase shift of the PA signal at each experimental frequency The sum of the square of the difference between...

Ngày tải lên: 06/05/2014, 08:53

... direct nitridation of Sn over a broad range of temperatures i.e between 300–800 °C due to the formation of Sn droplets on the surface of the Si(111) While there is evidence of one dimensional ... rate of NH3 during the growth while keeping everything else equal at all temperatures so the direct nitridation of Sn alone under a flow of NH3 is not effective and leads to the deposition of Sn ... the direct nitridation of Sn with NH3 was promoted by the addition of NH4Cl into the Sn at a ratio of 1:1 by weight The reaction of NH4Cl with Sn was carried out under a flow of NH3 keeping the flow...

Ngày tải lên: 21/06/2014, 20:20

... ð3Þ In the case of In, we find that incorporation of NH4Cl leads to the complete transfer of the solids of In and NH4Cl into the gas stream of N2 Indium has a low melting point of 156 °C and once ... on Si(111) by direct oxidation of In with O2 at 1000 °C (a) Isolated NCs with diameter of 500 nm (b) Dendrite structure consisting of chains of NCs (c) Side view of NC chains 123 494 Nanoscale ... high temperatures [19–21] In the case of direct oxidation of In with O2 a shell of In2O3 forms around the molten source of In This shell inhibits the transfer of In into the gas stream, so it is...

Ngày tải lên: 22/06/2014, 01:20