Surface Microchemical Reactions during Hydrogenated Silicon Growth Studied by In-situ ESR Technique

2000 ◽  
Vol 609 ◽  
Author(s):  
Satoshi Yamasaki
Keyword(s):  
Crystalline Silicon ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Dynamic Surface ◽  
Hydrogenated Silicon ◽  
Silicon Growth ◽  
Hydrogenated Amorphous

ABSTRACTThe in-situ ESR technique is applied to a plasma-enhanced chemical vapor deposition (PECVD) system in order to investigate the surface microchemical reactions during the growth of hydrogenated amorphous silicon (a-Si:H) and plasma treatments of H2 and Ar gases on a- Si:H. The growth model of a-Si:H and the role of H atoms on a-Si:H films are discussed using the experimental results. The recent results on the dynamic surface reactions of crystalline silicon with oxygen molecules in an ultra-high-vacuum ESR system are introduced.

Effects of Substrate Temperature and Atomic Hydrogen Flow on the Mircocrystallinity of Evaporated Hydrogenated silicon Films

2002 ◽  
Vol 715 ◽  
Author(s):  
A.J. Stoltz ◽  
Whitney Mason ◽  
J.D. Benson ◽  
J.H. Dinan ◽  
K. McCormack ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Atomic Hydrogen ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Hydrogenated Silicon ◽  
Hydrogen Flow ◽  
A Value ◽  
Hydrogenated Amorphous

AbstractAs a first step toward an understanding of the chemical and structural role of hydrogen in hydrogenated amorphous silicon, we utilized electron beam evaporation in an ultra high vacuum environment to deposit films of amorphous silicon and systematically dosed these films with atomic hydrogen during deposition. Secondary Ion Mass Spectroscopy (SIMS) data indicated that hydrogen concentration can be varied from the detection limit of SIMS to a value in excess of 1021 atoms cm-3. The intentional addition of hydrogen caused the concentration to fall from in an excess of 1021 atoms*cm-3 to below 1018 atoms*cm-3.

Ultra-high vacuum chemical vapor deposition and in situ characterization of titanium oxide thin films

1991 ◽  
Vol 6 (9) ◽  
pp. 1913-1918 ◽  
Author(s):  
Jiong-Ping Lu ◽  
Rishi Raj
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Titanium Oxide ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Titanium Isopropoxide ◽  
Ultra High Vacuum

Chemical vapor deposition (CVD) of titanium oxide films has been performed for the first time under ultra-high vacuum (UHV) conditions. The films were deposited through the pyrolysis reaction of titanium isopropoxide, Ti(OPri)4, and in situ characterized by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). A small amount of C incorporation was observed during the initial stages of deposition, through the interaction of precursor molecules with the bare Si substrate. Subsequent deposition produces pure and stoichiometric TiO2 films. Si–O bond formation was detected in the film-substrate interface. Deposition rate was found to increase with the substrate temperature. Ultra-high vacuum chemical vapor deposition (UHV-CVD) is especially useful to study the initial stages of the CVD processes, to prepare ultra-thin films, and to investigate the composition of deposited films without the interference from ambient impurities.

New Insights on Superlow Friction Mechanisms of Hydrogenated Amorphous Carbon

2005 ◽  
Author(s):  
Julien Fontaine
Keyword(s):  
Mechanical Properties ◽  
Amorphous Carbon ◽  
Friction Mechanisms ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Critical Importance ◽  
Hydrogenated Amorphous Carbon ◽  
Friction Regime ◽  
Hydrogenated Amorphous

Some hydrogenated amorphous carbon (a-C:H) films have the peculiarity to exhibit coefficients of friction in the millirange, known as “superlow friction”, under inert environments like dry nitrogen or high vacuum. However, this “superlubricity” is only observed for some coatings and sometimes for very short duration. The role of tribofilm in the superlow friction regime observed on various a-C:H films sliding against steel pins has been investigated by performing experiments in ultra-high vacuum and hydrogen ambient. Tribofilm build-up appears to be controlled by interactions with oxide layers. Then, evolutions of the tribofilm will depend both on the composition of a-C:H film and on interactions with environment, through tribochemical reactions. Furthermore, the mechanical properties of the films are correlated with the achievement of superlow friction. All these results suggest that surface rheological properties are of critical importance in reaching superlow friction regime with a-C:H films.

A Mechanism of Sliding on the Nanometer-Thick Ag Layers

2005 ◽  
Author(s):  
F. Honda ◽  
M. Goto
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
High Vacuum ◽  
High Energy ◽  
Thin Layers ◽  
Ultra High Vacuum ◽  
Wear And Friction ◽  
Thickness Measurements

Tribological performance of sub-nano to nanometer-thick Ag layers deposited on Si(111) have been examined to understand the role of surface thin layers to the wear and friction characteristics. The slider was made of diamond sphere of 3 mm in radius. Sliding tests were carried out in an ultra-high vacuum environment (lower than 4 × 10−8 Pa) and analyzed in-situ by Auger electron spectroscopy (AES) for the quantitative thickness-measurements, by reflection high-energy electron diffraction (RHEED) to clarify the substrate cleanliness and crystallography of the Ag films, and by scanning probe microscopy (SPM) for the morphology of the deposited/slid film surfaces. As the results, a minimum of the friction coefficient 0.007 was observed from the film thickness range of 1.5–10 nm, and exactly no worn particles were found after 100 cycles of reciprocal sliding. Results have directly indicated that solid Ag(111) sliding planes allowed to reduce the friction coefficient very low without any detectable wear particles, and Ag nanocrystallites in Ag polycrystalline layers increase the size to 20–40 nm order, during sliding. The friction coefficient was slightly dependent to the normal load. Results were discussed on the role of the surface atoms to the friction, and a mechanism of sliding on Ag thin layers.

The Effect of Different Oxidizing Atmospheres on the Initial Kinetics of Copper Oxidation as Studied In Situ UHV-TEM

1999 ◽  
Vol 589 ◽  
Author(s):  
Mridula D. Bharadwaj ◽  
Anu Gupta ◽  
J. Murray Gibson ◽  
Judith C. Yang
Keyword(s):  
Water Vapor ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Solid State Reactions ◽  
Copper Oxidation ◽  
High Vacuum Condition ◽  
Ultra High Vacuum Condition ◽  
Kinetics Of

AbstractEffect of moisture on the oxidation of copper was studied using in situ UHV-TEM. The ultra high vacuum condition is required for minimum contamination effects. The initial observations show that the water vapor reduces the oxide as well as reduces the rate of oxidation if both oxygen gas and water vapor are simultaneously used. Based on these observations, we have speculated on the role of moisture in the solid state reactions involved in copper oxidation

A Comparison of Magnetic Properties of Thin Films of Fe/GaAs(100) and Ni/MICA

1992 ◽  
Vol 280 ◽  
Author(s):  
Bruce Andrien ◽  
David Miller
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Film Thickness ◽  
Gaas Substrate ◽  
High Vacuum ◽  
Auger Spectroscopy ◽  
Ultra High Vacuum ◽  
In Situ Adsorption

ABSTRACTA comparison between the morphology and magnetic properties has been made with thin films of Fe grown on GaAs(lOO) and of Ni grown on natural mica in the 10Å to 1000Å thickness range, in ultra high vacuum. The films are characterized in-situ by Auger spectroscopy and by an in-situ UHV M/H hysteresis loop tracer. If the films are thermally annealed, above 550°C for less than a few seconds, the film morphology changes. The Fe films form surface assembled clusters which are epitaxial with the GaAs substrate with diameters of order of the original average film thickness, while the Ni films grow large grains. The Auger signals show that the Fe clustering exposes the GaAs substrate while the Ni films are continuous and cover the mica substrate. In-situ adsorption studies of CO on the Ni films were consistent with the continuous nature of the Ni films. Hysteresis M/H curves are taken as a function of thickness and plots of coercivity versus film thickness or average cluster size shows a maximum near 100Å for both the Ni and the Fe films. The maximum is believed to be due to a trade-off between super-paramagnetism and magnetostatic forces, but with the grains in the Ni film playing the role of the clusters in the Fe film.

Heteroepitaxy: The Missing Link Between Surface Chemistry and Dry Corrosion

2000 ◽  
Vol 619 ◽  
Author(s):  
Judith C. Yang ◽  
Mridula Dixit Bharadwaj ◽  
Lori Tropia
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Oxygen Gas ◽  
Cu Oxidation

ABSTRACTWe have investigated the initial stages of Cu (001) oxidation in dry and moist oxidizing conditions using in situ ultra-high vacuum (UIHV) transmission electron microscopy (TEM). To investigate the role of moisture in the solid state reactions in Cu oxidation, we have examined the oxidation of Cu (001) with water vapor. Our observation indicate that water vapor causes reduction of Cu2O and retards the oxidation rate if both oxygen gas and water vapor are used simultaneously which contradicts the thermochemical data. We are also modeling the nucleation to coalescence of the oxide scale using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and have noted a qualitative agreement.

Self-assembled Ge quantum dots on SiC substrates grown by UHV-CVD

2002 ◽  
Vol 742 ◽  
Author(s):  
C. Calmes ◽  
V. Le ◽  
D. Bouchier ◽  
S. E. Saddow ◽  
V. Yam ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Vacuum ◽  
Chemical Vapor ◽  
High Energy ◽  
Surface Cleaning ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
First Results ◽  
Ge Quantum Dots

AbstractWe report our first results using a ultra high vacuum chemical vapor deposition (UHV-CVD) system to form Ge quantum dots on off-axis SiC substrates. Pure SiH4 and hydrogen-diluted GeH4 were used as gas precursors. The SiC substrates were chemically cleaned using the modified RCA process and the SiO2 layer was removed in-situ under a low SiH4 flow rate at a temperature between 1030°C and 1080°C. The Ge quantum dots were grown at a temperature of 750°C. In-situ reflection high-energy electron diffraction (RHEED) was used to monitor the surface cleaning and the Ge quantum dot growth. Ex-situ scanning electron microscope and atomic force microscopy were used to confirm the presence of Ge dots. The observed dots are smaller (350 Å width and 100 Å height) than similar Ge dots grown on Si.

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