Temperature Dependence of Nanoscale Friction Investigated with Thermal AFM Probes

2009 ◽  
Vol 1226 ◽  
Author(s):  
Christian Greiner ◽  
Jonathan R. Felts ◽  
Zhenting Dai ◽  
William P. King ◽  
Robert W. Carpick
Keyword(s):  
Room Temperature ◽  
Capillary Condensation ◽  
Constant Load ◽  
Native Oxide ◽  
Silicon Substrates ◽  
Ambient Atmosphere ◽  
Ambient Conditions ◽  
Nanoscale Friction ◽  
Kinetics Of

AbstractMeasurements of nanoscale friction between silicon AFM tips featuring an in-situ solid state heater and silicon substrates (both with native oxide) were performed. The temperature of the heater was varied between room temperature and approximately 650 °C. For these temperatures and the silicon substrate, the temperatures at the point of contact are estimated to range from room temperature to approximately 120±20 °C. Experiments were carried out in ambient atmosphere (˜30% relative humidity) and under dry nitrogen. Tests under constant load revealed that in the presence of ambient, friction increased with heater temperature whereas it did not change in dry nitrogen. For experiments carried out for different tip velocities (40 to 7800 nm/s), friction decreased with velocity in ambient and did not change in dry nitrogen. Both trends can be explained by thermally-assisted formation of capillary bridges between tip and substrate and the kinetics of capillary condensation under ambient conditions.

Surface Stability of Siderite Under Acidic Atmosphere: an Atomic Force Microscopy Study

1996 ◽  
Vol 453 ◽  
Author(s):  
R. M. Weaver ◽  
D. E. Grandstaff ◽  
G. H. Myer
Keyword(s):  
Microscopy Study ◽  
Ambient Atmosphere ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Preferential Growth ◽  
Surface Stability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Kinetics Of

AbstractThe reactivity of siderite (FeCO3) was investigated under ambient atmosphere and acidic aerosols using an atomic force microscope (AFM). Scans of freshly cleaved siderite crystals showed a relatively irregular microtopography, consisting of high-density kink-steps, compared to other isostructural carbonates (e.g. Iceland-spar calcite). Under ambient conditions siderite is inert with no spontaneous surface reconstruction as is reported for calcite. Under controlled conditions of pH and humidity, siderite was exposed to mists of HC1 and H2CO3 and the reaction was imaged with submicron resolution. The kinetics of the reaction varied with pH, humidity levels, and also as a function of the initial microtopography. Preferential growth and dissolution were observed as a function of initial topography and due to crystallographic anisotropies. Although extreme reaction conditions were excluded by certain aspects of AFM (high capillary forces, tip corrosion, charged surface), this technique has allowed real-time, in situ observations of surface reactions.

Kinetics of Pt Silicide Formation Studied by Spectral Ellipsometry

1997 ◽  
Vol 470 ◽  
Author(s):  
R. Schwarz ◽  
A. Dittrich ◽  
S. M. Zhou ◽  
M. Hundhausen ◽  
L. Ley ◽  
...  
Keyword(s):  
Activation Energy ◽  
Crystalline Silicon ◽  
Silicon Substrates ◽  
Silicide Formation ◽  
Spectral Ellipsometry ◽  
Step Process ◽  
Depth Profiles ◽  
Ellipsometric Angle ◽  
Kinetics Of

ABSTRACTSuicide formation during thermal annealing of thin Pt layers deposited by evaporation onto crystalline silicon substrates was studied by in-situ spectral ellipsometry. As was shown in an earlier study, Pt suicide is formed in a two-step process with intermediate stages of Pt2Si and PtSi at temperatures of about 190 and 240 °C, respectively. We observed a shift of about 15 °C of the di- and monosilicide formation, when the anneal rate was lowered from 3 to 1 K/min. The analysis of the reaction kinetics using the normalized ellipsometric angle δ yields a good fit to the data for different anneal rates with an activation energy of (1.6 ± 0.2) eV. The underlying model of suicide formation through a multilayer system was checked with depth profiles and compositional information obtained from Rutherford Backscattering.

In situ high temperature X-ray diffraction study of the kinetics of phase separation in the uranium-plutonium mixed oxide (U0.55Pu0.45)O2-x

2014 ◽  
Vol 1645 ◽  
Author(s):  
Romain VAUCHY ◽  
Renaud.C. BELIN ◽  
Anne-Charlotte ROBISSON ◽  
Fiqiri HODAJ
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Mixed Oxides ◽  
Oxygen Stoichiometry ◽  
X Ray Diffraction ◽  
Fundamental Interest ◽  
X Ray ◽  
Uranium Plutonium ◽  
Kinetics Of

ABSTRACTUranium-plutonium mixed oxides incorporating high amounts of plutonium are considered for future nuclear reactors. For plutonium content higher than 20%, a phase separation occurs, depending on the temperature and on the oxygen stoichiometry. This phase separation phenomenon is still not precisely described, especially at high plutonium content. Here, using an original in situ fast X-ray diffraction device dedicated to radioactive materials, we evidenced a phase separation occurring during rapid cooling from 1773 K to room temperature at the rate of 0.05 and 2 K per second for a (U0.55Pu0.45)O2-x compound under a reducing atmosphere. The results show that the cooling rate does not impact the lattice parameters of the obtained phases at room temperature but their fraction. In addition to their obvious fundamental interest, these results are of utmost importance in the prospect of using uranium-plutonium mixed oxides with high plutonium content as nuclear fuels.

In-situ Measurement of GaAs Optical Constants and Surface Quality, as Functions of Temperature

1991 ◽  
Vol 222 ◽  
Author(s):  
Huade Yao ◽  
Paul G. Snyder
Keyword(s):  
Room Temperature ◽  
Optical Constants ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Native Oxide ◽  
Time Data ◽  
Gaas Sample ◽  
Optical Thermometer ◽  
Surface Changes

ABSTRACTIn-situ spectroscopic ellipsometry (SE) was applied to monitor GaAs (100) surface changes induced at elevated temperatures inside an ultrahigh vacuum (UHV) chamber (<1×10−9 torr base pressure, without As overpressure). The real time data showed clearly the evolution of the native-oxide desorption at ∼577°C, on a molecular-beam-epitaxy (MBE)-grown GaAs (100) surface. In addition, surface degradation was found before and after the oxide desorption. A clean and smooth surface was obtained from an arsenic-capped, MBE-grown GaAs sample, after the arsenic coating was evaporated at ∼350 °C inside the UHV. Pseudodielectric functions <ε>GaAs, from 1.6 eV to 4.5 eV, were obtained through the SE measurements, from this oxide-free surface, at temperatures ranging from room temperature (RT) to ∼610 °C. These <ε> data were used as reference data to develop an algorithm for determining surface temperatures from in-situ SE measurements, thus turning the SE instrument into a sensitive optical thermometer.

LPCVD Si3N4growth retardation on silicon native oxide compared with in situ HF vapour-deglazed silicon substrates

1991 ◽  
Vol 6 (11) ◽  
pp. 1100-1102 ◽  
Author(s):  
F Martin ◽  
F Bertin ◽  
H Sprey ◽  
E Granneman
Keyword(s):  
Native Oxide ◽  
Silicon Substrates

Phase Transformations in Sol-Gel PZT Thin Films

2000 ◽  
Vol 623 ◽  
Author(s):  
D.P. Eakin ◽  
M.G. Norton ◽  
D.F. Bahr
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Structural Changes ◽  
Sol Gel ◽  
Ex Situ ◽  
Ambient Conditions ◽  
Crystalline Films ◽  
In Situ Heating

AbstractThin films of PZT were deposited onto platinized and bare single crystal NaCl using spin coating and sol-gel precursors. These films were then analyzed using in situ heating in a transmission electron microscope. The results of in situ heating are compared with those of an ex situ heat treatment in a standard furnace, mimicking the heat treatment given to entire wafers of these materials for use in MEMS and ferroelectric applications. Films are shown to transform from amorphous to nanocrystalline over the course of days when held at room temperature. While chemical variations are found between films crystallized in ambient conditions and films crystallized in the vacuum conditions of the microscope, the resulting crystal structures appear to be insensitive to these differences. Significant changes in crystal structure are found at 500°C, primarily the change from largely amorphous to the beginnings of clearly crystalline films. Crystallization does occur over the course of weeks at room temperature in these films. Structural changes are more modest in these films when heated in the TEM then those observed on actual wafers. The presence of Pt significantly influences both the resulting structure and morphology in both in situ and ex situ heated films. Without Pt present, the films appear to form small, 10 nm grains consisting of both cubic and tetragonal phases, whereas in the case of the Pt larger, 100 nm grains of a tetragonal phase are formed.

Heteroepitaxial Metal Oxides on Silicon by Laser Ablation

1990 ◽  
Vol 191 ◽  
Author(s):  
D. B. Fenner ◽  
D. K. Fork ◽  
G. A. N. Connell ◽  
J. B. Boyce ◽  
F. A. Ponce ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Single Crystal Silicon ◽  
Native Oxide ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Crystal Silicon ◽  
Ybco Films ◽  
Zero Resistance ◽  
High Degree

ABSTRACTThin epitaxial films of cubic - fluorite structured PrO2 and YSZ (yttria- stabilized zirconia) were grown on single crystal silicon substrates using the laser ablation - deposition technique. X-ray diffraction theta two - theta, omega rocking and phi scans indicate a high degree of epitaxial orientation of the films to the Si lattice. The highest quality of epitaxy was obtained with the PrO2 [111] oriented normal to Si(111) surfaces and the cubic YSZ [100] normal to Si(100) surfaces. For both PrO2 and YSZ, high epitaxial quality required the removal of the Si native oxide prior to deposition and careful control of the deposition environment. It was further found that the YSZ films on Si(100) were an excellent surface for subsequent laser ablation of YBCO films by the usual in situ process. The resistivity of this YBCO was ≈ 250 micro-ohm-cm at 300 K, extrapolated to the resistivity -temperature origin, showed a sharp transition to zero resistance at ≈ 85 K and was nearly identical to high quality YBCO films deposited on (bulk) YSZ substrates.

Synthesis and kinetics of decomposition of some novel S-nitrosothiols

1999 ◽  
Vol 77 (5-6) ◽  
pp. 550-556 ◽  
Author(s):  
Andrew P Munro ◽  
D Lyn H. Williams
Keyword(s):  
Nitric Oxide ◽  
Room Temperature ◽  
Alternative Pathway ◽  
Copper Catalysis ◽  
Induction Periods ◽  
Kinetics Of Decomposition ◽  
Initial Generation ◽  
Kinetics Of ◽  
Reaction Schemes

TheS-nitrosothiols 2-acetamido-2-deoxy-S-nitroso-1-thio-β-D-glucopyranose 3,4,6-triacetate (GPSNO) and S-nitroso-N-carbamyl-D,L-penicillamine (SNCP) were synthesized by S-nitrosation of the corresponding thiols, isolated, and fully characterized. The nitrosothiol (TGSNO) from 1-thioglycerol was obtained as a red gelatinous liquid, which decomposed rapidly at room temperature and so was not characterized. The kinetics of decomposition of GPSNO showed that there is a surprisingly large thermal pathway overlaid with a Cu2+/RS- catalyzed reaction. The results strongly suggest that the product disulfide complexes Cu2+ (for which there is some spectral evidence), leading to incomplete conversion by that route. Ascorbate also acts as a Cu2+ reductant. Another S-nitroso sugar, S-nitroso-1-thio-β-D-glucose (SNTG), behaved very similarly from solutions generated and used in situ. The decomposition of TGSNO shows induction periods suggesting that slow initial generation of Cu+ (the true catalyst) is taking place. There appears to be also a significant alternative pathway (analogous to that found for GPSNO), where the rate appears to be independent of [Cu2+], but very unusually this pathway is effectively halted by addition of EDTA either at the start of the reaction or at a later time. Reaction schemes are put forward to account for these unusual reaction characteristics.Key words: S-nitrosothiols, nitric oxide, ascorbate, copper catalysis.

Transport in Thermal Dip Pen Nanolithography

2004 ◽  
Author(s):  
Brent A. Nelson ◽  
Tanya L. Wright ◽  
William P. King ◽  
Paul E. Sheehan ◽  
Lloyd J. Whitman
Keyword(s):  
Electron Beam ◽  
Atomic Force Microscope ◽  
Electron Beam Lithography ◽  
Room Temperature ◽  
Optical Lithography ◽  
Ambient Conditions ◽  
Atomic Force ◽  
Resolution Limits ◽  
Dip Pen Nanolithography

The manufacture of nanoscale devices is at present constrained by the resolution limits of optical lithography and the high cost of electron beam lithography. Furthermore, traditional silicon fabrication techniques are quite limited in materials compatibility and are not well-suited for the manufacture of organic and biological devices. One nanomanufacturing technique that could overcome these drawbacks is dip pen nanolithography (DPN), in which a chemical-coated atomic force microscope (AFM) tip deposits molecular ‘inks’ onto a substrate [1]. DPN has shown resolution as good as 5 nm [2] and has been performed with a large number of molecules, but has limitations. For molecules to ink the surface they must be mobile at room temperature, limiting the inks that can be used, and since the inks must be mobile in ambient conditions, there is no way to stop the deposition while the tip is in contact with the substrate. In-situ imaging of deposited molecules therefore causes contamination of the deposited features.

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