In-Situ Caiciss Study Of Dynamic Process Of Oxygen Desorption On TiO2-Terminated SrTiO3(001) Surface

1997 ◽  
Vol 474 ◽  
Author(s):  
T. Nishihara ◽  
O. Ishiyama ◽  
S. Hayashi ◽  
M. Shinohara ◽  
M. Yoshimoto ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Room Temperature ◽  
Incident Angle ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ion Scattering ◽  
Peak Intensity ◽  
Ion Scattering Spectroscopy ◽  
Topmost Layer

ABSTRACTThe topmost atoms of TiO2 - terminated SrTiO3(001) annealed at temperatures between room temperature and 800°C in ultra high vacuum (UHV), have been studied by means of in-situ coaxial impact collision ion scattering spectroscopy (CAICISS). Both time-of-flight spectra at the incident angle of 45.0°C along [ 100] azimuth and of 35.3°C along [110] azimuth revealed Ti and weak O peaks and no Sr peak at 150°C, which means that the topmost layer at 150°C is terminated by TiCh-plane, completely. On the other hand, as increasing the substrate temperature, Sr peak began to appear above 400°C. This Sr peak intensity from both directions was drastically increased with elevating the substrate temperature. This indicates that the topmost O and Ti atoms desorb from the surface at the higher substrate temperature. The ratio Sr/Ti corresponds to the amount of the topmost oxygen or titanium vacancies due to the desorption. It was found that 40 % of the topmost oxygen atoms and 32% of the topmost titanium atoms desorb from TiO2-terminated SrTiO3(001) surface at 800°C. The activation energies for oxygen and titanium desorption were 0.28eV and 0.40eV, respectively.

Investigation of Thin Pd-Ge Layer Formation Using Synchrotron Vacuum Ultraviolet Photoemission Spectroscopy

1990 ◽  
Vol 181 ◽  
Author(s):  
P. L. Meissner ◽  
J. C. Bravman ◽  
T. Kendelewicz ◽  
K. Miyano ◽  
W. E. Spicer ◽  
...  
Keyword(s):  
Room Temperature ◽  
Vacuum Ultraviolet ◽  
Diffusion Mechanism ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Photoemission Spectroscopy ◽  
Layer Formation ◽  
Primary Reaction ◽  
Ultraviolet Photoemission Spectroscopy

ABSTRACTThe formation of Pd-Ge layers was studied as a function of deposition and annealing using synchrotron Ultraviolet Photoemission Spectroscopy (UPS). Pd depositions ranging in thickness from 0.5 monolayers (ML) to 44 ML were examined in-situ on Ge (111) cleaved in ultra-high vacuum. The primary reaction components appear to be Pd2Ge and PdGe. Comparison of bulk and surface sensitive Ge 3d core levels for even the highest coverages indicates that Ge segregates to the surface at room temperature. Such low temperature segregation suggests that Ge can diffuse via a rapid diffusion mechanism.

IN SITU STM INVESTIGATION OF Ge NANOSTRUCTURES WITH AND WITHOUT Sb ON GRAPHITE

2006 ◽  
Vol 13 (02n03) ◽  
pp. 241-249
Author(s):  
SUNIL SINGH KUSHVAHA ◽  
ZHIJUN YAN ◽  
MAO-JIE XU ◽  
WENDE XIAO ◽  
XUE-SEN WANG
Keyword(s):  
Room Temperature ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Initial Stage ◽  
Defect Sites ◽  
Substrate Defects

Germanium was deposited onto highly oriented pyrolytic graphite (HOPG) with and without antimony in ultra-high vacuum. The surface morphology was analyzed using in situ scanning tunneling microscopy (STM) at room temperature (RT). The film grows exclusively in 3D island mode and was affected significantly by substrate defects. At initial stage, nucleation of cluster occurred at step edges and defect sites. Later, we found various types of Ge nanostructures on HOPG in different deposition conditions and stages, including cluster chains, cluster islands, nanowires, and double layer ramified islands at RT. Compact Ge islands were observed when depositing at a substrate temperature of 450 K or after an annealing at 600 K following RT deposition. In addition, the pre-deposited Sb on graphite enhances the sticking probability and suppresses the surface diffusion of Ge atoms, resulting in a significant increase in Ge cluster island density on HOPG terraces.

Initial Oxidation Kinetics of Copper (110) Thin Films As Investigated By IN SITU UHV-TEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 1274-1275
Author(s):  
Guang-Wen Zhou ◽  
Mridula D.Bharadwaj ◽  
Judith C.Yang
Keyword(s):  
Surface Science ◽  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Science Methods ◽  
Metal Oxidation ◽  
Initial Oxidation ◽  
Transmission Electron ◽  
Kinetics Of

In the study of metal oxidation, there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mostly examined the adsorption of up to ∽1 monolayer (ML) of oxygen on the metal surface, where as both low and high temperature bulk oxidation studies have mainly focused on the growth of an oxide layer at the later stages of oxidation. Hence, we are visualizing the initial oxidation stages of a model metal system by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), where the surfaces are atomically clean, in order to gain new understanding of these ambiguous stages of oxidation. We have previously studied the growth of Cu2O islands during initial oxidation of Cu(100) film. We are presently investigating the initial stages of Cu(110) oxidation, from 10−4 Torr O2 to atmospheric pressures and temperature range from room temperature to 700 °C.

XPS, AES and Leed Studies of The Interaction Between The Si(100) 2×1 Surface and Cadmium Deposited at Room Temperature

1995 ◽  
Vol 382 ◽  
Author(s):  
S. Santucci ◽  
S. Di Nardo ◽  
L. Lozzi ◽  
M. Passacantando ◽  
P. Picozzi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Early Stage ◽  
High Vacuum ◽  
Amorphous Structure ◽  
Ultra High Vacuum ◽  
Energy Position ◽  
X Ray

ABSTRACTVery thin films of cadmium, with a mean thickness between 1 Å and 500 Å, were deposited by thermal evaporation in ultra-high-vacuum on a Si(100) 2×1 surface held at room temperature. In situ X-ray Photoelectron Spectroscopy and Auger Electron Spectroscopy were performed in order to investigate the interaction between the silicon substrate and the deposited cadmium. In samples with deposited mean thickness up to 3 Å, cadmium and silicon are found to be strongly interacting. In fact both XPS and AES spectra show evident changes in shape and energy position leading to the conclusion that a chemical compound between Cd and Si is formed. No diffusion between cadmium and silicon is observed, so the cadmium atoms deposited after the first 3 Å show a bulk character. The analysis of the first derivative intensity of the Si L23VV and Cd M5N45N45 Auger signals, varying the amount of deposited Cd, indicates the formation of islands in the early stage of the Cd growth. These islands show an amorphous structure as observed by using the LEED spectroscopy.

Influence of Oxidation On Boron Sgregation to Grain Boundaries of In-Situ Fractured Ni3Al Alloys

2000 ◽  
Vol 654 ◽  
Author(s):  
S. A. Koch ◽  
D. T. L van Agterveld ◽  
G. Palasantzas ◽  
J. Th. M. De Hosson
Keyword(s):  
Grain Boundaries ◽  
Room Temperature ◽  
High Vacuum ◽  
Spot Size ◽  
Ultra High Vacuum ◽  
Nucleation Sites ◽  
Ni Oxidation ◽  
Subsequent Exposure ◽  
Auger Microscopy

AbstractScanning electron and scanning Auger microscopy studies were performed on in-situ fractured B-doped hypostoichiometric Ni3Al alloys. The Auger measurements on the fracture surface showed a very small amount or the total absence of B. Further, B segregated to the grain boundaries during subsequent exposure to the ambient system ultra-high vacuum environment at room temperature. The B segregation appeared to be driven by a mechanism of electronic nature related to Ni enrichment and O supplied from the environment. Ni-oxidation at room temperature is in accordance with model predictions for small beam sizes (≤10 µm) based on the premise that the electron beam creates additional nucleation sites around of which oxide growth occurs. With increasing the size of the e-beam the oxidation process becomes slower and chemisorption of oxygen plays a significant role. As a result the Ni-oxide depth decreases drastically with increasing spot size and offers an alternative route for monitoring the thickness of NiO in a nanometer range.

Ion induced formation of Silicon nitride substrate and GaN overlayer growth at room temperature on Si (111) surface

2009 ◽  
Vol 1202 ◽  
Author(s):  
Praveen Kumar ◽  
Mahesh Kumar ◽  
Govind Gupta ◽  
Bodh R. Mehta ◽  
Sonanda M. Shivaprasad
Keyword(s):  
Silicon Nitride ◽  
Room Temperature ◽  
Chemical Shifts ◽  
High Vacuum ◽  
Ion Bombardment ◽  
Ultra High Vacuum ◽  
Nitride Semiconductors ◽  
Interface Reactions ◽  
Lower Temperature

AbstractGaN and related nitride semiconductors have attracted great attention in view of their wide applications in photonics and high temperature & high power electronic devices. Among other issues, reduction of defect densities by forming these interfaces at lower temperature and on novel substrates has been the motivation for several researchers. In the present study ion-induced conversion of Si (111) surface into silicon nitride at room temperature is optimized and used as substrate for the growth of Ga films. These Ga films are again nitrided by optimal N+ ion bombardment. Experiments have been performed in-situ in an ultra high vacuum chamber equipped with a Ga source and X-ray photoelectron spectrometer (XPS) at base pressure of 2×10-10 torr. The energy dependence of the nitridation is carefully performed at constant flux. The results clearly demonstrate the Si-N bond formation after a energy of 2 keV and the formation of GaN layer after 800eV of ion bombardment on Si (111) 7×7 surface and Ga adsorbed silicon nitride surface, respectively. The FWHM and chemical shifts in the core-level spectra of Si(2p), Ga(2p) and N(1s) have been analyzed to probe the interface reactions. The results demonstrate a possible novel and low temperature approach towards the integration of III-nitride & silicon technologies, since silicon nitride bonds can act as barriers to dislocation propagation.

In-situ Microscopic Study of Cu Intragranular Electromigration

2005 ◽  
Vol 907 ◽  
Author(s):  
Kuan-Chia Chen ◽  
Chien-Neng Liao ◽  
Wen-Wei Wu ◽  
Lih-Juann Chen
Keyword(s):  
Electric Current ◽  
Crystal Orientation ◽  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Selective Area ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Atomic Image

AbstractElectromigration (EM) in unpassivated copper lines at room temperature has been investigated in ultra-high vacuum by in-situ transmission electron microscopy (TEM). The electric current induced atomic migration in a (211)-oriented Cu grain has been successfully recorded in real-time video. The atomic image of the (211) grain was found to vanish directionally when applying an electric current density of 2 × 106 A/cm2 through the Cu line. The results suggested that the combination of {111} planes and <110> directions to be the easiest EM path in crystalline copper. By performing selective area diffraction (SAD) analysis on a single Cu grain with (111) crystal orientation, some unusual electron diffraction patterns appeared after passing an electric current through the Cu line. It is believed that the EM-induced Cu twinning may be held responsible for the unique diffraction patterns

Structural and Magnetic Properties of Epitaxially Grown Fcc Fe/Cu(100) and Fe/CaF2/Si(111)

1994 ◽  
Vol 332 ◽  
Author(s):  
M.R. Scheinfein ◽  
S.D. Healy ◽  
K.R. Heim ◽  
Z.J. Yang ◽  
J.S. Drucker ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Kerr Effect ◽  
Room Temperature ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Imaging

ABSTRACTWe have used nanometer spatial resolution secondary electron and Auger electron imaging in an ultra-high vacuum scanning transmission electron microscope to characterize microstructure in ultrathin films of Fe/Cu(100) grown at room temperature and Fe/CaF2/Si(111) grown at room temperature and 150 C. Thin film microstructure was correlated in situ with magnetic properties by using the surface magneto-optic Kerr effect.

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