Observation of GaAs/Si Interface by Tem: Effect of Annealing on the Structure

1987 ◽  
Vol 102 ◽  
Author(s):  
H. Heral ◽  
A. Rocher ◽  
M. N. Charasse ◽  
A. Georgakilas ◽  
J. Chazelas ◽  
...  
Keyword(s):  
Cross Section ◽  
Gaas Layer ◽  
Heat Treatments ◽  
Interface Roughness ◽  
Crystalline Quality ◽  
Threading Dislocations ◽  
Section Technique ◽  
Before And After ◽  
Plane View

ABSTRACTWe present in this paper the effect of heat treatments applied to a 400 nm GaAs layer grown by MBE on a (001) Silicon substrate. These heat treatments have been applied during or after the growth of the GaAs, in order to improve the crystalline quality of the layer. RBS and TEM observations have been performed to study the improvement of the crystalline quality of the GaAs layer. Specimens, prepared by cross-section technique along both (110) and (170) planes and plane view, have been studied by TEM. Observations of cross-section by HREM show an interface roughness of about 1.5 nm before and after heat treatments. A roughness, observed also by RHEED, appears in the first stage of growth. Although the density of threading dislocations decreases after heat treatments.

scholarly journals Moderate heat treatments enhance the quality of traded natural shea butter

2020 ◽  
Vol 22 (1) ◽  
pp. 17-26
Author(s):  
A.O. Oyedele ◽  
O.A. Igbeneghu ◽  
T.I. Alade ◽  
O.O. Akinmusire
Keyword(s):  
Microbiological Quality ◽  
Poor Quality ◽  
Heat Treatments ◽  
Shea Butter ◽  
Physicochemical Quality ◽  
Melting Temperatures ◽  
Before And After ◽  
Human Use ◽  
C 30

Natural shea butter (NSB), extracted by traditional methods resulting in its poor quality, is nevertheless widely traded within Africa and beyond due to its several useful applications. This study examined effects of simulated laboratory/domestic heat treatments on quality of the commodity obtained from a cross section of Nigerian markets. Physicochemical and microbiological qualities of NSB samples procured from four selected  markets located across three Nigerian states were evaluated by standard methods before and after graduated thermal stress treatments from 50 through 120 °C over 5, 15, or 30 min durations, respectively, and filtration at 60 °C. Mean physicochemical quality values of NSB samples determined, namely: specific gravity at 29 °C (0.90-0.94); softening, melting temperatures (33-36, 36-39 °C; respectively); acid, iodine, and saponification values (10.5- 29.3, 46.4-59.1, 110-470; respectively), were not adversely or significantly altered by the thermal treatment types and stresses. Whereas all untreated NSB samples demonstrated microbial contamination (total viable counts: 3 6 10 -10 cfu/g) with Pseudomonas, Klebsiella, Staphylococcus, Bacillus, Aspergillus, or Candida species, the graduated heat treatments produced varied sanitizing effects. Higher temperatures (100, 120 °C) gave greater and more rapid cleansing action than the lower temperatures (50, 75 °C), both intensity-ranges being aided by length of holding time. Hot filtration eliminated all the NSB contaminants. In conclusion, while untreated NSB is found grossly contaminated by microbes, unhygienic and unsafe for human use, this study has demonstrated efficient contaminants-cleansing action of heat treatments (³100 °C × ³ 30 min) on NSB, and the total sanitizing effect of hot filtration process. Key words: Natural shea butter, Physicochemical quality, Microbiological quality, Heat treatment, Hot filtration.

Crystalline Quality Evaluation of SiC p/n Column Layers Formed by Trench-Filling-Epitaxial Growth

2020 ◽  
Vol 1004 ◽  
pp. 445-450
Author(s):  
Kohei Adachi ◽  
Ryoji Kosugi ◽  
Shi Yang Ji ◽  
Yasuyuki Kawada ◽  
Hiroyuki Fujisawa ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Epitaxial Growth ◽  
Epitaxial Layer ◽  
Quality Evaluation ◽  
Crystalline Quality ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Threading Dislocation Density

We evaluated crystalline quality of SiC p/n column layers over 20 μm thickness formed by trench-filling-epitaxial growth. Although threading dislocation density of trench-filling-epitaxial layer is almost same as flat n-type epitaxial layer, threading dislocations are localized in only trench-filled p-columns. We consider that threading dislocations migrated toward p-columns around trench bottom during trench-filling-epitaxial growth.

Improvement of the Crystalline Quality of β-Ga2O3 Films by High-Temperature Annealing

2012 ◽  
Vol 725 ◽  
pp. 273-276
Author(s):  
Motoki Takahara ◽  
Suguru Funasaki ◽  
Jyun Kudou ◽  
Isao Tsunoda ◽  
Kenichiro Takakura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Crystalline Quality ◽  
High Temperature Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Si Doped ◽  
Scanning Electron

For the purpose of improving the crystalline quality of undoped and Si doped β-Ga2O3 films, high temperature annealing at 900°C was performed. The crystalline quality of the films investigated using scanning electron microscopy and X-ray diffraction. Also the conductivity of the films is compared before and after the annealing. After the 900°C annealing, the XRD peaks intensity corresponding to β-Ga2O3 is increased. This result indicates that the crystalline quality improves by the high temperature annealing.

Confinement of Threading Dislocations in Simox with a GeSi Strained Layer

1990 ◽  
Vol 198 ◽  
Author(s):  
F. Namavar ◽  
E. Cortesi ◽  
D.L. Perry ◽  
E.A. Johnson ◽  
N.M. Kalkhoran ◽  
...  
Keyword(s):  
Alloy Layer ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Epitaxial Silicon ◽  
Strained Layers ◽  
Strained Layer ◽  
Si Substrates ◽  
Plane View ◽  
Gesi Layer

ABSTRACTWe have investigated improving the crystalline quality of epitaxial silicon grown on SIMOX by confining threading dislocations in the original Si top layer using a GeSi strained layer. Epitaxial Si/GeSi/Si structures were grown by CVD on SIMOX and Si substrates with a GeSi alloy layer about 1000 − 1500 angstroms thick with Ge concentrations of about 0−20%. A Ge concentration in the alloy layer of about 5.5% or higher appears to be necessary in order to bend any of the threading dislocations from the original SIMOX top layer. For a higher Ge concentration of about 16%, most of the threading dislocations appear to be bent and confined by the GeSi layer. In addition, the GeSi strained layers grown by CVD (at about 1000°C) appear to be high quality and no misfit dislocations were observed in the regions studied by XTEM and plane view TEM.

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

Kepuasan Masyarakat Terhadap Pelayanan Kelurahan Setelah Pemekaran Di Tangerang Selatan

Liquidity ◽  
2018 ◽  
Vol 2 (2) ◽  
pp. 151-159
Author(s):  
Pitri Yandri
Keyword(s):  
Public Perception ◽  
Service Personnel ◽  
Urban Services ◽  
Hospitality Workers ◽  
Care Workers ◽  
Before And After ◽  
Cartesian Diagram ◽  
Better Than

The purpose of this study is (1) to analyze public perception on urban services before and after the expansion of the region, (2) analyze the level of people's satisfaction with urban services, and (3) analyze the determinants of the variables that determine what level of people's satisfaction urban services. This study concluded that first, after the expansion, the quality of urban services in South Tangerang City is better than before. Secondly, however, public satisfaction with the services only reached 48.53% (poor scale). Third, by using a Cartesian Diagram, the second priority that must be addressed are: (1) clarity of service personnel, (2) the discipline of service personnel, (3) responsibility for care workers; (4) the speed of service, (5) the ability of officers services, (6) obtain justice services, and (7) the courtesy and hospitality workers.

Strategic Role of Zakat in Multidimensional Quality of Life in Sijunjung, Indonesia

2018 ◽  
Vol 15 (1) ◽  
pp. 55-72
Author(s):  
Herlin Hamimi ◽  
Abdul Ghafar Ismail ◽  
Muhammad Hasbi Zaenal
Keyword(s):  
Quality Of Life ◽  
Positive Impact ◽  
Wealth Distribution ◽  
Absolute Poverty ◽  
Before And After ◽  
The Status ◽  
Being There ◽  
The Impact

Zakat is one of the five pillars of Islam which has a function of faith, social and economic functions. Muslims who can pay zakat are required to give at least 2.5 per cent of their wealth. The problem of poverty prevalent in disadvantaged regions because of the difficulty of access to information and communication led to a gap that is so high in wealth and resources. The instrument of zakat provides a paradigm in the achievement of equitable wealth distribution and healthy circulation. Zakat potentially offers a better life and improves the quality of human being. There is a human quality improvement not only in economic terms but also in spiritual terms such as improving religiousity. This study aims to examine the role of zakat to alleviate humanitarian issues in disadvantaged regions such as Sijunjung, one of zakat beneficiaries and impoverished areas in Indonesia. The researcher attempted a Cibest method to capture the impact of zakat beneficiaries before and after becoming a member of Zakat Community Development (ZCD) Program in material and spiritual value. The overall analysis shows that zakat has a positive impact on disadvantaged regions development and enhance the quality of life of the community. There is an improvement in the average of mustahik household incomes after becoming a member of ZCD Program. Cibest model demonstrates that material, spiritual, and absolute poverty index decreased by 10, 5, and 6 per cent. Meanwhile, the welfare index is increased by 21 per cent. These findings have significant implications for developing the quality of life in disadvantaged regions in Sijunjung. Therefore, zakat is one of the instruments to change the status of disadvantaged areas to be equivalent to other areas.

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