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  • 1
    Online Resource
    Online Resource
    Initial stages of growth during boron carbide chemical vapor deposition
    American Vacuum Society ; 1987
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 5, No. 5 ( 1987-09-01), p. 2823-2828
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 5, No. 5 ( 1987-09-01), p. 2823-2828
    Abstract: The initial stages of growth of boron carbides from a BCl3/H2/hydrocarbon vapor on molybdenum were investigated. The initial growth of boron carbide was strongly dependent on the type and concentration of hydrocarbon in the vapor. From the results of the experiments it was concluded that an ‘‘overlayer’’ of adsorbed hydrocarbons was formed on the surface. The overlayer inhibited some reactions on the surface and affected the growth rate, the morphologies of the nuclei, as well as the growth rates of molybdenum borides.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.574315
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1987
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 2
    Online Resource
    Online Resource
    Selective deposition of tungsten—prediction of selectivity
    American Vacuum Society ; 1985
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 3, No. 6 ( 1985-11-01), p. 2298-2302
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 3, No. 6 ( 1985-11-01), p. 2298-2302
    Abstract: Preferential or selective chemical vapor deposition to a substrate region is based on a difference in thermochemical stability between different substrate regions. The higher this difference is, the higher selectivity is expected. In this paper a thermodynamic analysis of selective deposition of tungsten from H2 and WF6 on silicon regions in the presence of silicon dioxide is presented. At the initial stages of growth—silicon present in the vapor—the selectivity is favored by a low temperature, a low total pressure and a high WF6 concentration in the vapor. For the continuation—growth on the deposited tungsten—a low total pressure, a low WF6 concentration in the vapor and a higher temperature than that used initially should be chosen for highest selectivity. From the analysis it is also seen that simultaneous etching and tungsten oxide/tungsten deposition may occur on the silicon dioxide. The technique used to analyze the selective tungsten deposition process seems to be a useful tool for optimizing the selectivity in a given system and for reducing or eliminating undesired side reactions.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.572868
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1985
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 3
    Online Resource
    Online Resource
    Chemical and structural study of electrically passivating Al2O3/Si interfaces prepared by atomic layer deposition
    American Vacuum Society ; 2012
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 30, No. 4 ( 2012-07-01)
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 30, No. 4 ( 2012-07-01)
    Abstract: Aluminum oxide (Al2O3) layers, prepared by atomic layer deposition (ALD), provide excellent surface passivation properties on crystalline Si surfaces, which are of major importance for photovoltaic applications. Beyond the chemical passivation by reduction of the electronic surface state density, a supportive field effect passivation mechanism emerges at the Al2O3/Si interface. The atomic origin of the fixed negative charges that are responsible for the field effect is currently under discussion. In this contribution, thin layers of Al2O3 with thicknesses ranging from the submonolayer region to several nanometers have been grown on Si substrates by means of thermal ALD. The principle elements of the samples have been quantified by x-ray photoelectron spectroscopy as a function of the film thickness. Changes at the interface upon thermal annealing have been investigated in detail. After the first few ALD cycles an imperfect Al2O3 layer is found together with the formation of an ultrathin SiOx interlayer. Continued deposition leads to stoichiometric Al2O3 growth. Within the first ∼1 nm from the Si interface, additional O (“excess O”), surpassing the Al2O3 and SiO2 stoichiometry, is observed. The excess O does not completely react with the Si surface to SiO2 during thermal annealing. Therefore, interstitial O in near-interface Al2O3 is suggested to provide the fixed negatively charged states.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.4704601
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2012
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 4
    Online Resource
    Online Resource
    Growth characteristics of photolytic laser-induced chemical vapor deposition of tungsten from WF6
    American Vacuum Society ; 1992
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 10, No. 5 ( 1992-09-01), p. 3131-3135
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 10, No. 5 ( 1992-09-01), p. 3131-3135
    Abstract: ArF laser induced chemical vapor deposition (CVD) of W onto (100)Si from a WF6/H2/Ar mixture and with the laser beam in parallel to the substrate surface was studied. The influence of substrate temperature on the deposition rate was investigated in a broad range (25–450 °C) for both focused and unfocused beam conditions and compared with thermal CVD data. Above the threshold temperature for the thermal process, 250 °C, a combined thermal and photolytic process takes place. Below 250 °C the laser induced photolytic process yields deposition with a nearly temperature independent deposition rate of about 100 Å/min when a focused beam is used. For an unfocused beam a slightly lower deposition rate was observed. The distance between the laser beam and the substrate surface had only a slight influence on the deposition rate. For the focused beam conditions the deposition rate was only reduced by roughly 10% when the distance was increased from 0 to 8 mm. For the unfocused case the deposition rate increased, without reaching the focused beam values, upon increasing the beam to substrate distance in the range 0–8 mm. The substrate temperature had a strong influence on the resistivity of the deposited films for both laser-induced and thermal processes. For obtaining a low resistivity value, 8 μΩ cm, a substrate temperature above 350 °C was required. This was mainly due to the fact that the high-resistivity β phase was formed at lower temperatures. The influence of H2 concentration on the growth rate was investigated by replacing H2 with Ar. A small amount of H2 was enough to increase the deposition rate considerably. Use of Ar diluted gas resulted also in a higher deposition rate. Finally, the deposition rate increased linearly with increased total pressure.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.577876
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1992
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 5
    Online Resource
    Online Resource
    Step-type and step-density influences on CO adsorption probed by reflection absorption infrared spectroscopy using a curved Pt(1 1 1) surface
    American Vacuum Society ; 2017
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 35, No. 3 ( 2017-05-01)
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 35, No. 3 ( 2017-05-01)
    Abstract: In comparison to flat single crystals, the continuous variation of structure provided by curved crystals offers many benefits for the study of physical and chemical processes at surfaces. However, the curvature of the surface also creates experimental challenges. For infrared spectroscopy, in particular, adsorbates on metal samples are typically probed by grazing-incidence reflection-absorption infrared spectroscopy (RAIRS). In this geometry, a convex crystal acts as a strongly diverging mirror. The authors describe how the experimental difficulties introduced by a cylindrical surface can be resolved for RAIRS. A complementary mirror, placed directly downfield of the curved crystal within the vacuum chamber, minimizes the divergence created by the sample. By simply translating the infrared focus across the sample, the authors probe adsorbate vibrational spectra as a function of local step-type and step-density with high sensitivity and spatial resolution. Time-consuming sample exchange, and the concomitant sample-to-sample experimental errors, are eliminated. The authors apply this new technique to carbon monoxide adsorption on a curved Pt(1 1 1) crystal and use it to resolve the influence of step-type and step-density on the CO stretch vibration as a function of coverage.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.4976617
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2017
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 6
    Online Resource
    Online Resource
    Chemical vapor deposition of alpha aluminum oxide for high-temperature aerospace sensors
    American Vacuum Society ; 2000
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 18, No. 4 ( 2000-07-01), p. 1653-1658
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 18, No. 4 ( 2000-07-01), p. 1653-1658
    Abstract: Thin-film thermocouples and strain gages are being developed for high-temperature application on aerospace propulsion hardware for both development test purposes and as active control sensors. The critical technology necessary in the fabrication of the sensor is an adherent, dense, and homogeneous dielectric to provide electrical isolation at engine operating temperatures. Techniques are being developed to create a crystalline aluminum oxide dielectric formed by a combination of a thermally grown oxide (TGO) from a NiCoCrAlY hardcoating, which is then enhanced with the addition of a chemical vapor deposited (CVD) crystalline aluminum oxide layer. This article will focus on the process development used to deposit the α alumina layer on the TGO using CVD in a coldwall reactor at 1100 °C. The chemistry employed in this process is the pyrolitic decomposition of aluminum tri-isopropoxide. The hexagonal (HCP) α phase is achieved at deposition temperatures of 1000–1100 °C, as confirmed by x-ray diffraction analysis. By eliminating gas phase and hot wall decomposition, this approach minimizes precursor depletion effects, yielding a more dense and uniform film morphology. Conformal coatings up to 10 μm thick with high resistivity and good adhesion and hardness have been observed on complex airfoil geometries. Growth rates up to 10 μm/h are possible, although low growth rates lead to more desirable film properties. The kinetics of the deposition indicate that the reaction proceeds by a mass transport limited mechanism. Uniform temperature control over highly complex geometry is desirable, but not essential for uniform film growth. Results indicate that the gas flow uniformity and the precursor transport rate are the critical variables.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.582401
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2000
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 7
    Online Resource
    Online Resource
    Area selective chemical vapor deposition of boron carbide achieved by molecular masking
    American Vacuum Society ; 1988
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 6, No. 3 ( 1988-05-01), p. 1733-1735
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 6, No. 3 ( 1988-05-01), p. 1733-1735
    Abstract: The difference in adsorption behavior of hydrocarbons on molybdenum and titanium was used to attain area selective deposition of boron carbide to titanium substrate areas. Hydrocarbons, added to the reaction gas mixture, caused a considerable decrease in the nucleation rate on molybdenum but not on titanium. Hence conditions for selective deposition to titanium areas were obtained. The selectivity was improved by increasing the hydrocarbon concentration in the vapor or by substituting ethylene for methane. This demonstrates that molecular masking of substrate areas can be used to induce or improve the selectivity in a chemical vapor deposition process even at high temperatures (1400 K).
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.575281
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1988
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 8
    Online Resource
    Online Resource
    C49/C54 phase transformation during chemical vapor deposition of TiSi2
    American Vacuum Society ; 1994
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 12, No. 1 ( 1994-01-01), p. 161-168
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 12, No. 1 ( 1994-01-01), p. 161-168
    Abstract: The initial stages of chemical vapor deposition of TiSi2 from TiCl4, H2, and Si(100) have been investigated with respect to the phase formation sequence. The result showed that the metastable C49 TiSi2 phase was formed prior to the equilibrium C54 TiSi2 phase. As the growth continued, the C49 phase was transformed to the C54 phase. X-ray diffraction analyses showed that both TiSi2 phases exhibited an epitaxial-like growth with respect to the substrate. Moreover, the transformation from the C49 phase to the C54 phase was favored by increased film thickness rather than high-temperature annealing. The results could be explained by an interfacial stabilization effect where the metastable C49 phase is stabilized by epitaxy. In addition, the influence of oxygen and carbon on the process was investigated by adding O2and C2H4 to the reaction gas mixture. Oxygen had no effect while a minor stabilization of the C49 phase was observed when carbon was introduced during deposition.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.578914
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1994
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 9
    Online Resource
    Online Resource
    Determination of two‐dimensional crystal structures by infrared spectroscopy
    American Vacuum Society ; 1990
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 8, No. 3 ( 1990-05), p. 2653-2657
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 8, No. 3 ( 1990-05), p. 2653-2657
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.576688
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1990
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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  • 10
    Online Resource
    Online Resource
    Applications of ab   initio quantum molecular dynamical relaxation: Silicon(111)-5×5 surface reconstruction and aluminum deposited on silicon(100)
    American Vacuum Society ; 1992
    In:  Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 10, No. 4 ( 1992-07-01), p. 2046-2051
    Details
    In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 10, No. 4 ( 1992-07-01), p. 2046-2051
    Abstract: We present two applications of a first principles quantum molecular dynamics technique. In the first, we have determined the relaxed atomic geometry and the corresponding electronic structure of the Si(111) surface in the 5×5 dimer–adatom-stacking fault structure. We find a unique low temperature behavior for this surface, namely, corrugation of the adatoms on each side of the 5×5 unit cell, which we verify by the use of perturbation theory. In a second application, we have determined the relaxed atomic geometry and the corresponding electronic structure of the Al:Si(100) surface in both the 2×2 and the 2×3 reconstructions. In particular, we find that the Al dimers on this surface are parallel to, rather than perpendicular to, the Si dimer direction.
    Type of Medium: Online Resource
    ISSN: 0734-2101 , 1520-8559
    URL: Article
    DOI: 10.1116/1.578022
    RVK:
    UA 4921
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1992
    detail.hit.zdb_id: 1475424-1
    detail.hit.zdb_id: 797704-9
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