scholarly journals AlAs as a Bi blocking barrier in GaAsBi multi-quantum wells: Structural analysis

2017 ◽  
Vol 57 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Renata Butkutė ◽  
Martynas Skapas ◽  
Algirdas Selskis ◽  
Virginijus Bukauskas ◽  
Sandra Stanionytė ◽  
...  
Keyword(s):  
High Resolution ◽  
Quantum Wells ◽  
Crystal Quality ◽  
Ex Situ ◽  
High Temperature Treatment ◽  
Structural Quality ◽  
Technological Parameters ◽  
Quantum Well Structures ◽  
The Impact

Crystallographic properties of AlAs barriers in GaAsBi-based multi-quantum well structures grown on GaAs substrates by molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE) were studied. The quantum wells were grown at temperatures ranging from 160 to 350 °C. The width of GaAsBi quantum wells varied from 4 to 20 nm. The optimization of technological parameters for the growth of high crystalline quality AlAs barriers at low temperatures was performed. To explore the impact of high temperature treatment on crystal quality, surface roughness and chemical composition stability, ex situ rapid thermal annealing was performed at 650–750 °C for 180 s in nitrogen ambiance. The structural quality of AlAs barriers, the morphology and sharpness of the interfaces between GaAsBi quantum wells and AlAs barriers were studied by high resolution X-ray diffraction, atomic force microscopy and high resolution transmission electron microscopy, respectively. In this study it was demonstrated that MEE allows one to achieve higher crystal quality of AlAs barriers at much lower temperatures in comparison to MBE. The blocking of Bi out-diffusion from the GaAsBi quantum wells toward the surface was shown for both MBE and MEE grown AlAs barriers.

scholarly journals Problems of Analyzing Microstructure Images in Assessing the Impact of Technological Parameters of Combined Strain Wave Hardening on the Quality of the Surface Layer

2019 ◽  
Author(s):  
Андрей Киричек ◽  
Andrey Kirichek ◽  
Дмитрий Соловьев ◽  
Dmitriy Solovyev ◽  
Александр Хандожко ◽  
...  
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Strain Wave ◽  
Technological Parameters ◽  
Steel Microstructure ◽  
Main Indicator ◽  
Metallographic Images ◽  
Surface Layer Quality ◽  
The Impact

The problems of analyzing metallographic images and the method of their solution using modern software for the analysis of metallographic images are described. There is given an analysis of microstructure images as the main indicator of the surface layer quality by the example of studying the research results of strain wave hardening combinations and chemical-thermal treatment, in particular the influence of previous strain wave hardening and subsequent thermal and chemical- thermal treatment on the alloy steel microstructure or previous thermal and chemical- thermal treatment and subsequent strain wave hardening. On the basis of the analysis the effectiveness of strain wave hardening and chemical and thermal treatment is established.

scholarly journals Study of the Influence of Technological Parameters on Generating Flat Part with Cylindrical Features in 3D Printing with Resin Cured by Optical Processing

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1941
Author(s):  
Aurel Tulcan ◽  
Mircea Dorin Vasilescu ◽  
Liliana Tulcan
Keyword(s):  
3D Printing ◽  
Flat Surface ◽  
Coordinate Measuring Machine ◽  
3D Printer ◽  
Light Control ◽  
Technological Parameters ◽  
Optical Processing ◽  
Measuring Machine ◽  
The Impact

The objective of this paper is to determine how the supporting structure in the DLP 3D printing process has influences on the characteristics of the flat and cylindrical surfaces. The part is printed by using the Light Control Digital (LCD) 3D printer technology. A Coordinate Measuring Machine (CMM) with contact probes is used for measuring the physical characteristics of the printed part. Two types of experiment were chosen by the authors to be made. The first part takes into consideration the influence of the density of the generated supports, at the bottom of the printed body on the characteristics of the flat surface. In parallel, it is studying the impact of support density on the dimension and quality of the surface. In the second part of the experiment, the influence of the printed supports dimension on the flatness, straightness and roundness of the printed elements were examined. It can be observed that both the numerical and dimensional optimum zones of the support structure for a prismatic element could be determined, according to two experiments carried out and the processing of the resulting data. Based on standardized data of flatness, straightness and roundness, it is possible to put in accord the values determined by measurement within the limits of standardized values.

scholarly journals Introductory Talk

1988 ◽  
Vol 132 ◽  
pp. xxxiii-xxxiii
Author(s):  
G. Cayrel de Strobel
Keyword(s):  
High Resolution ◽  
The Sun ◽  
In The Beginning ◽  
The Impact

The idea to organize a Conference on high S/N spectroscopy came to me several years ago, in the beginning of the eighties, when the first tracings of Reticon spectra of 8 and 9 magnitude stars were published. I suddendly realized that the quality of those spectra was comparable to those we find in the at lasses of the Sun, Procyon, Arcturus and of a very few other very bright stars. I thought at that epoch, probably at the top of Mauna Kea, that when high-resolution spectroscopists will have collected enough high S/N results, then, time would be ripe to discuss the impact of these results on our Knowledge of Stellar Physics.

Study of the structural quality of heteroepitaxial silicon-on-sapphire structures by high-resolution X-ray diffraction, X-ray reflectivity, and electron microscopy

2014 ◽  
Vol 59 (3) ◽  
pp. 315-322 ◽  
Author(s):  
A. E. Blagov ◽  
A. L. Vasiliev ◽  
A. S. Golubeva ◽  
I. A. Ivanov ◽  
O. A. Kondratev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray

Analysis of Fracture Process and Common Defects in Casting Alloys EN43100 Manufactured by Die Casting Technology

2014 ◽  
Vol 1077 ◽  
pp. 39-43
Author(s):  
Stefan Gaspar ◽  
Ján Pasko
Keyword(s):  
Airline Industry ◽  
Fracture Process ◽  
Die Casting ◽  
Structural Quality ◽  
Quality Properties ◽  
Casting Technology ◽  
Casting Alloys ◽  
The Impact ◽  
Casting Production

Recent research in the process of die casting production of aluminium alloys which are nowadays deeply implemented in the rapidly developing automobile, shipping and airline industry aims to increase the manufacture and quality properties of the casting in order to obtain its high mechanical properties at acceptable economic costs. In terms of ensuring the quality indicators in the production of aluminium castings it is necessary to pay close attention to internal structural quality of the castings characterized by type and extent of foundry defects (cavities, Al2O3 particles, internal cold laps). The presenting contribution deals with the analysis of the fracture process, the microorganism disturbance of test samples, the impact of casting speed on the occurrence and extent of the castings porosity and reasons for the internal foundry defects of casting alloys EN 43100 manufactured by die casting technology.

The Influence of the Temperature Gradient on the Defect Structure of 3C-SiC Grown Heteroepitaxially on 6H-SiC by Sublimation Epitaxy

2010 ◽  
Vol 645-648 ◽  
pp. 367-370 ◽  
Author(s):  
Maya Marinova ◽  
Alkyoni Mantzari ◽  
Milena Beshkova ◽  
Mikael Syväjärvi ◽  
Rositza Yakimova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Temperature Gradient ◽  
Defect Structure ◽  
Temperature Gradients ◽  
Structural Quality ◽  
Fault Density ◽  
Transmission Electron

In the present work the structural quality of 3C-SiC layers grown by sublimation epitaxy is studied by means of conventional and high resolution transmission electron microscopy. The layers were grown on Si-face 6H-SiC nominally on-axis substrates at a temperature of 2000°C and different temperature gradients, ranging from 5 to 8 °C /mm. The influence of the temperature gradient on the structural quality of the layers is discussed. The formation of specific twin complexes and conditions for lower stacking fault density are investigated.

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