Laser-induced positive ion and neutral atom/molecule emission from single-crystal CaHPO 4 ·2 H 2 O: The role of electron-beam-induced defects

1999 ◽  
Vol 69 (7) ◽  
pp. S547-S552 ◽  
Author(s):  
M.L. Dawes ◽  
W. Hess ◽  
Y. Kawaguchi ◽  
S.C. Langford ◽  
J.T. Dickinson
Keyword(s):  
Electron Beam ◽  
Single Crystal ◽  
Neutral Atom ◽  
Induced Defects ◽  
Positive Ion

The Adsorption of Liquid and Vapor Water on TiO2 (110) Surfaces: The Role of Defects

1994 ◽  
Vol 357 ◽  
Author(s):  
Li-Qiong Wang ◽  
Don R. Baer ◽  
Mark. H. Engelhard
Keyword(s):  
Electron Beam ◽  
Vapor Pressure ◽  
Liquid Water ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Water Exposure ◽  
Pressure Water ◽  
Electronic Defects ◽  
Induced Defects

AbstractThe adsorption of liquid and vapor water on defective and nearly defect-free TiO2 (110) surfaces has been examined using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). The study has focused on examining electronic defects as created in vacuum and after exposure to both liquid and vapor water. The defective surfaces were prepared by electron-beam exposure and Ar+ bombardment. With exposure up to 104 L low vapor pressure (<10−5 Torr) water to defective surfaces, little or no changes on Ti 3d defect intensities were observed, in agreement with the previous studies. However, defect intensities were greatly reduced after exposing defective surfaces to ∼ 108 L higher vapor pressure (0.2 - 0.6 Torr) water for 5 min. More significantly, XPS and UPS spectra showed that electron-beam induced defects were completely removed upon liquid water exposure, while defects created by Ar+ bombardment were only partially removed. It was found that surface defects created by Ar+ bombardment were removed more readily than sub-surface defects. For a nearly defect-free surface, water coverages were ∼ 0.02 ML at 104 L exposure to low vapor pressure water, ∼ 0.07 ML at 108 L exposure to higher vapor pressure water, and ∼ 0.125 ML with liquid water exposure, respectively.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

Oxide Mediated Epitaxial Growth of CoSi2 in a Single Deposition Step

1999 ◽  
Vol 564 ◽  
Author(s):  
S. Ohmi ◽  
R. T. Tung
Keyword(s):  
Single Crystal ◽  
Epitaxial Growth ◽  
Diffusion Barrier ◽  
Blocking Layer ◽  
Deposition Step

AbstractA number of modifications of the oxide-mediated epitaxy (OME) technique are presented which have enabled the growth of thick (∼25–40nm) epitaxial CoSi2 layers in a single deposition sequence. The uses of (a) a thin Ti cap, (b) a thin Ti blocking layer, (c) the codeposition of Co-rich CoSix, and (d) the co-deposition of Col−xTix. have all been shown to lead to improved epitaxial quality over the pure Co OME process, for Co thickness greater than 6nm. Essentially uniform, single crystal silicide layers of over 25nm have been grown in a single deposition step. These results are supportive of the proposed role of a diffusion barrier/kinetics retarder on the part of the interlayer in the OME and the Ti-interlayer mediated epitaxy processes.

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