Fundamental Study of the Temperature Ramp-Up Influence for 3C-SiC Hetero-Epitaxy on Silicon (100)

2010 ◽  
Vol 645-648 ◽  
pp. 151-154 ◽  
Author(s):  
Philip Hens ◽  
Günter Wagner ◽  
Astrid Hölzing ◽  
Rainer Hock ◽  
Peter J. Wellmann
Keyword(s):  
Nucleation Rate ◽  
Carbon Layer ◽  
Low Density ◽  
High Quality ◽  
Fundamental Study ◽  
Temperature Range ◽  
Peak Intensity ◽  
Temperature Ramp ◽  
Domain Boundaries

Usually a waiting step at around 1000°C to 1100°C during the carbonization step for 3C-SiC on silicon is implemented for establishing a closed carbon layer to prevent the formation of voids. The latter, however, may lead to non-ideal nucleation conditions for high quality layers with a low density of domain boundaries. Our investigations indicate that a continuous ramp-up as fast as possible with no waiting step would be preferable. The worst layer quality, as measured by peak intensity and FWHM of the (200) reflection of 3C SiC, can be found at a temperature of about 1000°C, which indicates that here the nucleation rate would be the highest. So longer periods within this temperature range should be avoided by applying high ramping speeds during the carbonization step.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

scholarly journals STUDY OF EFFECT OF DIFFERENT ORIGIN PIGMENTS ON FRICTIONAL PROPERTIES OF POLYUREA GREASES

2018 ◽  
Vol 59 (7) ◽  
pp. 68
Author(s):  
Vladimir N. Koshelev ◽  
Boris P. Tonkonogov ◽  
Anastasia Yu. Kilyakova ◽  
Karine G. Aleksanyan ◽  
Eldar M. Movsumzade ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Wide Temperature Range ◽  
Chemical Resistance ◽  
Important Task ◽  
High Quality ◽  
Urea Derivatives ◽  
Temperature Range ◽  
Frictional Properties ◽  
High Speeds ◽  
Different Origin

In connection with development of techniques and technologies and unification and substitution the most important task for Russia is to solve the problem of development and introduction of modern high-quality domestic greases. The most suitable in this respect is greases with the urea derivatives thickener — organic compounds containing in molecules one or more urea (urea, wreath) groups. In recent years, the production of these lubricants attracts increased attention of specialists, because they have unique exploitation characteristics: the combination of high-hydrolytic and chemical resistance, operability in a wide temperature range, thermo-strengthening lack, retention its properties at high speeds and specific loads, in contact with adverse environments, etc.  We received greases based on poly urea with the addition of pigment. The synthesized pigments have different structure and belong to different classes of compounds. We conducted a search for the most optimal structures and concentrations of pigments which are included in the poly urea grease.

Collision induced microwave absorption in N2, CH4, and CF4 in the gaseous and liquid phases

1977 ◽  
Vol 55 (6) ◽  
pp. 496-505 ◽  
Author(s):  
J. L. Urbaniak ◽  
I. R. Dagg ◽  
G. E. Reesor
Keyword(s):  
Liquid Phase ◽  
Microwave Absorption ◽  
Low Density ◽  
Temperature Range ◽  
Liquid Phases ◽  
Gas To Liquid

Measurements of collision induced microwave absorption at 2.3 cm−1 have been carried out on gaseous N2 in the temperature range from 124 to 156 K and on liquid N2 in the temperature range from 77 to 125 K. The low density gaseous measurements have been found to agree well with the previous microwave and infrared results and with existing theories. The dependence of the absorption on density has been obtained at 156 K up to a density of 400 amagat and the results compared with the absorption in the liquid at the same density. The absorption is found to be a function of temperature and density but does not depend on the molecules being in a gas or liquid phase. Results for liquid CH4 and CF4 are reported and compared with previous microwave gaseous results. In contrast to the results for N2 the dependence on the square of the density changes by a relatively small amount in going from the low density gas to liquid densities.

Control of Iron Disilicide Crystal Structure by Using Liquid Phase Obtained by Au-Si Eutectic Reaction

2015 ◽  
Vol 1760 ◽  
Author(s):  
Kensuke Akiyama ◽  
Yuu Motoizumi ◽  
Hiroshi Funakubo
Keyword(s):  
Liquid Phase ◽  
Photoluminescence Spectrum ◽  
Radiative Recombination ◽  
Single Phase ◽  
Eutectic Reaction ◽  
Substrate Surface ◽  
Low Density ◽  
Si Substrate ◽  
High Quality ◽  
Iron Disilicide

ABSTRACTThe Au-Si liquid phase was obtained by melting the Si surface via Au-Si eutectic reaction, which contributed to the formation of semiconducting iron disilicide (β-FeSi2), on Au-coated Si(100) substrates. By coating a substrate with an Au layer of 60 nm or more, the Au-Si liquid phase covered the entire Si substrate surface, and single-phase β-FeSi2 was grown on Si(100) substrates. A clear photoluminescence spectrum of β-FeSi2 indicated the formation of high-quality crystals with a low density of the non-radiative recombination center in the grains.

The quantum second virial coefficient of 3He at low density in the temperature range 0.005–10 K

2017 ◽  
Vol 95 (12) ◽  
pp. 1208-1214 ◽  
Author(s):  
O.T. Al-Obeidat ◽  
A.S. Sandouqa ◽  
B.R. Joudeh ◽  
H.B. Ghassib ◽  
M.M. Hawamdeh
Keyword(s):  
First Principles ◽  
Virial Coefficient ◽  
Scattering Length ◽  
Second Virial Coefficient ◽  
Repulsive Interaction ◽  
Saturation Curve ◽  
Low Density ◽  
S Wave ◽  
Temperature Range ◽  
The Many

The quantum second virial coefficient Bq for 3He is calculated from first principles at low density in the temperature range 0.005–10 K. By “first principles”, it is meant that the many-body phase shifts are first determined within the Galitskii–Migdal–Feynman formalism; they are then plugged into the Beth–Uhlenbeck formula for Bq. A positive Bq corresponds to an overall repulsive interaction; a negative Bq represents an overall attractive interaction. The s-wave scattering length a0 is calculated quite accurately as a function of the temperature T. The effect of the (low-density) medium on Bq is studied. Bq is then used to determine the volume of 3He at the saturation curve. The compressibility is evaluated as a measure of the non-ideality of the system.

scholarly journals Immersion freezing of ice nucleation active protein complexes

2013 ◽  
Vol 13 (11) ◽  
pp. 5751-5766 ◽  
Author(s):  
S. Hartmann ◽  
S. Augustin ◽  
T. Clauss ◽  
H. Wex ◽  
T. Šantl-Temkiv ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Pseudomonas Syringae ◽  
Nucleation Rate ◽  
Protein Complex ◽  
Protein Complexes ◽  
Ice Nucleation ◽  
Minor Importance ◽  
Class Iii ◽  
Temperature Range ◽  
Immersion Freezing

Abstract. Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between −5 °C to −38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about −6 °C to about −10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached to the outer membrane of intact bacteria or membrane fragments, (c) the temperature range in which heterogeneous droplet freezing occurs, and the fraction of droplets being able to freeze, both depend on the actual number of INA protein complexes present in the droplet ensemble, and (d) possible artifacts suspected to occur in connection with the drop freezing method, i.e., the method frequently used by biologist for quantifying ice nucleation behaviour, are of minor importance, at least for substances such as P. syringae, which induce freezing at comparably high temperatures. The last statement implies that for single ice nucleation entities such as INA protein complexes, it is the number of entities present in the droplet population, and the entities' nucleation rate, which control the freezing behaviour of the droplet population. Quantities such as ice active surface site density are not suitable in this context. The results obtained in this study allow a different perspective on the quantification of the immersion freezing behaviour of bacterial ice nucleation.

Backside Nickel Based Ohmic Contacts to n-Type Silicon Carbide

2008 ◽  
Vol 600-603 ◽  
pp. 635-638 ◽  
Author(s):  
Reza Ghandi ◽  
Hyung Seok Lee ◽  
Martin Domeij ◽  
Carl Mikael Zetterling ◽  
Mikael Östling
Keyword(s):  
Silicon Carbide ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Contact Resistivity ◽  
Optimum Conditions ◽  
Power Devices ◽  
High Quality ◽  
Temperature Range ◽  
Type Silicon ◽  
Different Temperatures

This work focuses on Ni ohmic contacts to the C-face (backside) of n-type 4H-SiC substrates. Low-resistive ohmic contacts to the wafer backside are important especially for vertical power devices. Ni contacts were deposited using E-beam evaporation and annealed at different temperatures (700-1050 °C) in RTP to obtain optimum conditions for forming low resistive ohmic contacts. Our results indicate that 1 min annealing at temperatures between 950 and 1000 °C provides high quality ohmic contacts with a contact resistivity of 2.3x10-5 Ωcm2. Also our XRD results show that different Ni silicide phases appear in this annealing temperature range.

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