Reflection electron microscopy of triangular quantum wells

1993 ◽  
Vol 51 ◽  
pp. 828-829
Author(s):  
M. Gajdardziska-Josifovska
Keyword(s):  
Electron Microscopy ◽  
Quantum Wells ◽  
Alloy Composition ◽  
Electronic Devices ◽  
Thin Layers ◽  
Compositional Gradient ◽  
Digital Alloy ◽  
Nominal Thickness ◽  
Reflection Electron Microscopy

Asymmetric triangular quantum wells (ATQW) have recently been developed to improve the absorption and emission characteristics of opto-electronic devices. A triangular compositional gradient is produced during epitaxial growth of AlxGa1-xAs on GaAs by either continuous variation of x or by alternate deposition of thin layers of the two compounds where the ratio of the layer thickness produces an average alloy composition. The knowledge of the compositional profile of the actual ATQW, as derived from HREM, has proven essential for the description of the photo-emission properties of the device. Recently, the technique of reflection electron microscopy has also been applied to multiple rectangular quantum wells of GaAs/AlxGa1-xAs with the encouraging result that layers with 1% Al can be distinguished from the GaAs layers. In this work we investigate the applicability of REM to characterization of ATQW.Triangular quantum wells were grown by MBE, employing the digital alloy method. Fig. 1 shows a schematic representation of the nominal thickness and composition of the studied ATQW.

Characterization of nanostructures by reflection electron microscopy

1990 ◽  
Vol 56 (25) ◽  
pp. 2566-2568 ◽  
Author(s):  
A. Scherer ◽  
B. P. Van der Gaag
Keyword(s):  
Electron Microscopy ◽  
Reflection Electron Microscopy

Complete Characterization of AlxGa1-xN/InxGa1-xN/GaN Devices by Sims

1997 ◽  
Vol 468 ◽  
Author(s):  
C. Huang ◽  
S. Mitha ◽  
J. W. Erickson ◽  
R. Clark-Phelps ◽  
Jack Sheng ◽  
...  
Keyword(s):  
Growth Rate ◽  
Reverse Engineering ◽  
Failure Analysis ◽  
Concurrent Engineering ◽  
Alloy Composition ◽  
Electronic Devices ◽  
Complete Characterization ◽  
Sims Analysis

ABSTRACTSIMS analysis was applied to the characterization of GaN, AlGaN/GaN and InGaN/GaN grown by MOCVD. Such characterization enables the control of purity and doping, and the determination of growth rate and alloy composition. The analysis can be performed on finished optoelectronic and electronic devices and this makes SIMS technique a powerful tool for failure analysis, reverse engineering, and concurrent engineering.

Characterization of Electrodeposited Cobalt/Platinum(Ill) Ultrathin Films and Multilayers

1995 ◽  
Vol 382 ◽  
Author(s):  
Y. Jyoko ◽  
S. Kashiwabara ◽  
Y. Hayashi
Keyword(s):  
Electron Microscopy ◽  
Ultrathin Films ◽  
Photoelectron Spectroscopy ◽  
Multilayered Structure ◽  
Cross Sectional ◽  
Composition Modulation ◽  
Potential Control ◽  
Transmission Electron ◽  
Reflection Electron Microscopy

ABSTRACTReflection electron microscopy (REM) studies of Co electrodeposition on Pt(111) singlecrystal surfaces under potential control have revealed a heteroepitaxial and simultaneous multinuclear multilayer growth in a range from several up to some ten monolayer coverages at room temperature. This growth process has been dependent upon the crystallization overpotential during electrodeposition. REM observations have also suggested the formation of an ordered CoPt3 alloy at the interface between the Pt/Co ultrathin bilayers grown epitaxially on Pt(111) surfaces. Auger and photoelectron spectroscopy experiments on the Pt/Co/Pt(111) system have confirmed a limited interdiffusion or interfacial alloying below the Pt overlayer leading to an induced magnetic moment on the Pt atoms. The Pt/Co interface exhibits electronic interface states of mainly Pt-5d character. Cross-sectional transmission electron microscopy (TEM) observations have provided the first direct experimental evidence for composition modulation across successive layers in a Pt/Co nanometer-multilayered structure prepared by electrodeposition.

Characterization of clean gallium phosphide (110) surfaces by reflection electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 284-285
Author(s):  
M. Gajdardziska-Josifovska ◽  
M.R. McCartney ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Gallium Phosphide ◽  
Compound Semiconductors ◽  
Ion Milling ◽  
Imaging Studies ◽  
Annealing Temperatures ◽  
Reflection Electron Microscopy ◽  
Reconstructed Surface

The clean (110) surface of GaP has been studied in UHV systems with diffraction and spectroscopy techniques and found to have a 1×1 reconstruction. However, no imaging studies have been reported characterizing the topography of the reconstructed surface. In this work we use reflection electron microscopy (REM) to determine the effects of ion-milling and annealing treatments used to clean the surface. The annealing temperatures for the compound semiconductors are limited by preferential sublimation of one component so we have undertaken heating to higher temperatures to study the surface dissociation and melting processes.

Structural Characterization of Molecular Beam Epitaxy Grown GaInNAs and GaInNAsSb Quantum Wells by Transmission Electron Microscopy

2004 ◽  
Vol 817 ◽  
Author(s):  
Tihomir Gugov ◽  
Mark Wistey ◽  
Homan Yuen ◽  
Seth Bank ◽  
James S. Harris
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Wells ◽  
Phase Segregation ◽  
Dark Field ◽  
Lower Growth ◽  
Transmission Electron ◽  
Material Uniformity

AbstractIn the past decade, the quaternary GaInNAs alloy has emerged as a very promising material for lasers in the 1.2-1.6 μm range with application in telecommunication fiber-optic networks. While most of the challenges in growing high quality laser material with emission wavelength out to 1.3 μm have been successfully resolved, extending the emission beyond 1.3 μm has proven to be quite difficult. Achieving emission out to 1.5 μm requires higher In (up to 40%) and N (up to 2%) compositions. This makes the growth of this thermodynamically unstable alloy quite difficult with phase segregation occurring even at lower growth temperatures. Recently, adding small amounts of antimony has dramatically improved the quality of the material and high luminescence has been demonstrated at wavelengths beyond 1.5 μm. In this study, high-resolution transmission electron microscopy (HRTEM) was used in a novel way in conjunction with dark-field (DF) TEM to elucidate the role of antimony in improving the material quality. The results show that antimony improves the material uniformity via reduction of the local compositional fluctuations of indium.

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