Chemical Bonding, Structure, and Morphology of Mg/∝-Al2O3 and MGO / ∝-Al2O3 Interfaces

1994 ◽  
Vol 357 ◽  
Author(s):  
Yan Yu ◽  
R.J. Lad
Keyword(s):  
Photoelectron Spectroscopy ◽  
Spinel Phase ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
High Energy Electron ◽  
Sapphire Surface ◽  
X Ray ◽  
Bonding Structure ◽  
Oxygen Anions

AbstractUltra-thin films of Mg and MgO were grown on ∝-Al2O3 (1012) surfaces (r-cut sapphire) and studied using reflection high energy electron diffraction (RHEED) and x-ray photoelectron spectroscopy (XPS). When Mg is deposited at 30°C in ultra-high vacuum (UHV), the first monolayer of Mg atoms chemically bonds to the oxygen anions of the sapphire surface. At Mg coverages above a monolayer, a polycrystalline metallic Mg overlayer is formed. Annealing above 250°C in UHV causes the metallic Mg to desorb from the surface. However, annealing above 250°C in 10−6 torr O2 produces a polycrystalline MgO film. This MgO film recrystallizes after annealing in O2 at 900°C for 60 minutes and exhibits a crystallographic orientation of MgO (100) // ∝-Al2O3 (1012). RHEED indicates that the recrystallized MgO layer dewets the sapphire surface and forms islands. When Mg is deposited at 30°C in 10−6 torr O2, a polycrystalline MgO layer is created. This layer also becomes recrystallized and dewets the sapphire surface after extended annealing in O2 at 900°C. No evidence for a MgAl2O4 spinel phase was observed.

Surface Structure of Sulfur Coated GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
Yoshihisa Fujisaki ◽  
Shigeo Goto
Keyword(s):  
Electron Beam ◽  
Surface Structure ◽  
Chemical Bond ◽  
Photoelectron Spectroscopy ◽  
Strong Dependence ◽  
High Energy ◽  
Chemical Bonds ◽  
High Energy Electron ◽  
X Ray ◽  
Beam Diffraction

AbstractSurface structure of (NH4)2S treated GaAs. is investigated using PL (PhotoLuminescence), XPS (X-ray Photoelectron Spectroscopy) and RHEED (Reflection of High Energy Electron beam Diffraction). The data taken with these techniques show the strong dependence upon the crystal orientations coming from the stabilities of chemical bonds of Ga-S and As-S on GaAs crystals. The greater enhancement of PL intensity, the clearer RHEED patterns and the smaller amount of oxides on (111)A than (111)B implies the realization of a more stable structure composed mainly of the Ga-S chemical bond.

Fundamental study of the interaction of Ti atoms with spruce surfaces

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 523-527 ◽  
Author(s):  
Lothar Klarhöfer ◽  
Florian Voigts ◽  
Dominik Schwendt ◽  
Burkhard Roos ◽  
Wolfgang Viöl ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Strong Interactions ◽  
Titanium Oxide Film ◽  
Fundamental Study ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Atoms

Abstract Metastable induced electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were applied to study the interaction of Ti metal atoms with spruce surfaces. Spruce surfaces were produced by planing splints from a spruce bar. Ti atoms were adsorbed from a metal evaporator under ultra-high vacuum conditions. The amount adsorbed corresponds to 10 monolayer equivalents. Strong interactions between the spruce surface and metals atoms occurred. Impinging Ti atoms were oxidized by the spruce surface. No Ti agglomeration or particle formation was observed. The surface was smoothed by the Ti applied and was completely covered by a titanium oxide film.

CORRELATION AMONG THE ELECTRONIC STATE IN Sn-DOPED YBCO SYSTEM

1991 ◽  
Vol 05 (08) ◽  
pp. 581-585
Author(s):  
H. ZHANG ◽  
S.Q. FENG ◽  
Q.R. FENG ◽  
X. ZHU
Keyword(s):  
Content Analysis ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Strong Correlation ◽  
Single Phase ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Electronic States ◽  
Ultra High Vacuum ◽  
X Ray

We have performed an X-ray photoelectron spectroscopy investigation on single-phase samples of Sn -doped YBCO system, together with structure analysis, oxygen content analysis, and superconductivity measurements. The experiment gave evidence that there is a strong correlation between the electronic states of copper and oxygen. When the sample was heated to 600°C for 20 minutes in vacuum chamber, the oxygen escaped from the sample, the binding energy of Cu 2p was decreased, and the two indistinct components of O 1s became clear. Keeping the sample in ultra-high vacuum for 24 hours, a similar result was obtained.

scholarly journals Investigation of interaction of Co, Mn and Fe atoms with the calcite by X-ray photoelectron spectroscopy

2019 ◽  
Vol 64 (1) ◽  
pp. 89-95
Author(s):  
T. T. Magkoev ◽  
V. B. Zaalishvili ◽  
O. G. Burdzieva ◽  
G. E. Tuaev ◽  
G. S. Grigorkina
Keyword(s):  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
X Ray ◽  
Surface Compounds ◽  
Adsorption Systems

Adsorption of atoms of Co, Mn, Fe on the calcite surface in ultra-high vacuum and the interaction of the formed adsorption systems with the water have been studied by means of X-ray photoelectron spectroscopy. It is shown that Mn and Fe form solid solutions CaCO3/Mn(Fe)CO3 on the calcite surface, whereas Co preferentially forms CoO and Co3O4. Upon interaction with water the surface compounds formed by Mn and Fe do not undergo notable changes, unlike the Co oxides which partially transform into soluble hydroxylated complexes.

scholarly journals Growth Mode Study of MgCl2 on Ti (0001) and SiO2 under Ultra High Vacuum by XPS

2012 ◽  
Vol 2 (6) ◽  
pp. 291-294
Author(s):  
S. Karakalos
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Magnesium Chloride ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Growth Mode ◽  
X Ray ◽  
Mode Study

The growth mode of MgCl2 on Ti (0001) and on SiO2 grown on Si (100) was investigated by X-ray Photoelectron Spectroscopy (XPS) under UHV conditions. Magnesium chloride grows on both Ti (0001) single crystal and SiO2 following the Frank-van der Merve, (FM) growth mode.

scholarly journals Selective Growth of Al2O3 on Size-Selected Platinum Clusters by Atomic Layer Deposition

2019 ◽  
Author(s):  
Timothy J. Gorey ◽  
Yang Dai ◽  
Scott Anderson ◽  
Sungsik Lee ◽  
Sungwon Lee ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Atomic Layer ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Dimensional Structure ◽  
Alumina Layer ◽  
X Ray ◽  
Layer Deposition

In heterogeneous catalysis, atomic layer deposition (ALD) has been developed as a tool to stabilize and reduce carbon deposition on supported nanoparticles. Here, we discuss use of high vacuum ALD to deposit alumina films on size-selected, sub-nanometer Pt/SiO2 model catalysts. Mass-selected Pt24 clusters were deposited on oxidized Si(100), to form model Pt24/SiO2 catalysts with particles shown to be just under 1 nm, with multilayer three dimensional structure. Alternating exposures to trimethylaluminum and water vapor in an ultra-high vacuum chamber were used to grow alumina on the samples without exposing them to air. The samples were probed in situ using X-ray photoelectron spectroscopy (XPS), low-energy ion scattering spectroscopy (ISS), and CO temperature-programmed desorption (TPD). Additional samples were prepared for ex situ experiments using grazing incidence small angle x-ray scattering spectroscopy (GISAXS). Alumina growth is found to initiate at least 60 times more efficiently at the Pt24 cluster sites, compared to bare SiO2/Si, with a single ALD cycle depositing a full alumina layer on top of the clusters, with substantial additional alumina growth initiating on SiO2 sites surrounding the clusters. As a result, the clusters were completely passivated, with no exposed Pt binding sites.

scholarly journals Microstructure and Optical Properties of E-Beam Evaporated Zinc Oxide Films—Effects of Decomposition and Surface Desorption

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3510
Author(s):  
Lukasz Skowronski ◽  
Arkadiusz Ciesielski ◽  
Aleksandra Olszewska ◽  
Robert Szczesny ◽  
Mieczyslaw Naparty ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Oxide Films ◽  
Growth Direction ◽  
Ultra High Vacuum ◽  
X Ray ◽  
Force Microscopy ◽  
Zinc Oxide Films

Zinc oxide films have been fabricated by the electron beam physical vapour deposition (PVD) technique. The effect of substrate temperature during fabrication and annealing temperature (carried out in ultra high vacuum conditions) has been investigated by means of atomic force microscopy, scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. It was found that the layer deposited at room temperature is composed of Zn and ZnO crystallites with a number of orientations, whereas those grown at 100 and 200 ∘C consist of ZnO grains and exhibit privileged growth direction. Presented results clearly show the influence of ZnO decomposition and segregation of Zn atoms during evaporation and post-deposition annealing on microstructure and optical properties of zinc oxide films.

Modification of a TEM for ultra-high-vacuum reflection-EM (UHV-REM) applications

1995 ◽  
Vol 53 ◽  
pp. 582-583
Author(s):  
Tung Hsu ◽  
Min-Yi Shih ◽  
A. V. Latyshev
Keyword(s):  
Electron Microscope ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Pole Piece ◽  
High Energy Electron ◽  
Normal Position ◽  
Crystal Surfaces ◽  
Specimen Holder

A JEOL JEM-100C electron microscope was modified by adding a cryogenic UHV specimen holder for studying clean crystal surfaces with the reflection high energy electron diffraction (RHEED) and REM techniques. The Si(111) (l×l) and (7×7) phase transitions have been successfully observed (Fig. 1). Further modification is in progress for better resolution and other functions. Fig. 2.a shows the unmodified specimen holder and the objective lens of the microscope. The cryogenic holder based on the Novosibirsk design is shown in Fig. 2.b. Liquid nitrogen is continuously pumped through the shell of the holder for achieving UHV inside. The tilt/rotation controls and the current for heating of the specimen are fed through the holder. In this modification, the specimen was not placed at the normal position of the lens and therefore is not at the best position for imaging and diffraction.A new holder is shown in Fig. 2.c. This holder is inserted into the pole piece to place the specimen at the normal position.

Epitaxy of 3d Metals on Semiconductors

1998 ◽  
Vol 05 (01) ◽  
pp. 273-278 ◽  
Author(s):  
Xiaofeng Jin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Critical Role ◽  
High Energy ◽  
Interface Structure ◽  
High Energy Electron ◽  
X Ray ◽  
3D Metals ◽  
Transmission Electron ◽  
Lattice Mismatched Epitaxy ◽  
Metal Phases

Growth of fcc Mn on GaAs(001), as an example of the lattice-mismatched epitaxy of 3d metals on semiconductors, has been studied using reflection high energy electron diffraction (RHEED), X-ray photoelectron spectroscopy (XPS) and the high resolution transmission electron microscope (HRTEM). The result shows that the interface structure plays a critical role in the epitaxial growth of 3d metals on semiconductors. A new recipe is proposed to search for more epitaxially grown 3d metal phases.

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