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.

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.

Energy-Dispersive Spectroscopy in A 400Kv Electron Microscope

1985 ◽  
Vol 43 ◽  
pp. 146-147
Author(s):  
S. Suzuki ◽  
Y. Bando ◽  
H. Kitajima ◽  
T. Honda ◽  
Y. Harada ◽  
...  
Keyword(s):  
Electron Beam ◽  
Energy Dispersive Spectroscopy ◽  
High Energy ◽  
Energy Dispersive ◽  
Resolving Power ◽  
Total Thickness ◽  
High Energy Electron ◽  
X Ray ◽  
Basic Performance ◽  
Electron Energy Loss

A Si(Li) detector for X-ray energy dispersive spectroscopy (EDS) has been installed on a 400 kV EM, the JEM-4000EX, which is also interfaced with a scanning device (ASID40) and electron energy loss spectrometer (ASEA40). The EM's basic performance, i.e., resolving power, is 0.23 nm at 400 kV. X-ray microanalysis in a high-voltage EM has many advantages, but few reports have been published because of some severe instrumental problems originating from it's high energy electron beam. To overcome these problems many modifications have been made on the EM column.The modifications are divided into two aspects. One is the reduction of bremsstrahlung and the other is the protection of the Si(Li) detector from hard X-ray radiation from the upper parts of the detector, especially condenser lens (CL) aperture. To reduce bremsstrahlung many parts of the wall which electron beam might hit are covered with graphite and the materials for CL fixed apertures are changed to light elements. To protect the detector X-ray shielding parts made of heavy metals (W, Ta, Pb) and with a total thickness of more than 30 mm are set between the CL aperture and the Si(Li) detector.

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.

Reflection Electron Diffraction of Catalase

1975 ◽  
Vol 33 ◽  
pp. 672-673
Author(s):  
T. K. Chatterjee ◽  
J. A. Spadaro ◽  
R. W. Vook
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Preliminary Report ◽  
Water Vapor Pressure ◽  
High Energy ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Reflection Electron Diffraction

Matricardi et al. have shown that high energy electron diffraction patterns of unstained and unfixed catalase may be obtained with a high voltage TEM using a hydration stage and that without such a stage TED patterns could not be obtained. They showed that such patterns were observed only when the water vapor pressure in the vicinity of the catalase was greater than 90 percent of the equilibrium value. They attributed their results to the destruction of the crystallinity of catalase when it is vacuum dried. Similar results using X-ray diffraction techniques have been reported. Matricardi et al. also noted effects due to radiation damage, whereby the number of reflections observed using the hydration stage decreased substantially with electron beam exposure. In the present preliminary report, it is shown that electron diffraction patterns can be obtained from unstained and unfixed catalase even when the crystals are exposed directly to the vacuum of the TEM but under such conditions whereby the electron beam intensity is reduced by up to approximately two orders of magnitude from that usually obtained in normal TED work on a TEM.

Study of KTiOPO4 surface by x-ray photoelectron spectroscopy and reflection high-energy electron diffraction

2002 ◽  
Vol 34 (1) ◽  
pp. 320-323 ◽  
Author(s):  
V. V. Atuchin ◽  
V. G. Kesler ◽  
N. Yu. Maklakova ◽  
L. D. Pokrovsky ◽  
V. N. Semenenko
Keyword(s):  
Electron Diffraction ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
X Ray
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