The Formation of Defects and Growth Interface Shapes in CZ Silicon

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

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Observations on the structure at the transformation interface of pearlite in steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174138 ◽

1990 ◽

Vol 48 (4) ◽

pp. 200-201

Author(s):

F. A. Khalid ◽

D. V. Edmonds

Keyword(s):

Room Temperature ◽

Thin Foil ◽

Carbon Steels ◽

Model Alloy ◽

Growth Interface ◽

Medium Carbon ◽

Solution Treated ◽

Medium Carbon Steels ◽

Alloy Carbide ◽

Hot Rolled

The austenite/pearlite growth interface in a model alloy steel (Fe-1 lMn-0.8C nominal wt%) is being investigated. In this particular alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature, thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the austenite/pearlite interface, as part of a programme of aimed at studying alloy carbide precipitation reactions at this interface which can result in significant strengthening of microalloyed low- and medium- carbon steels L Similar studies of interface structure, made on a partially decomposed high- Mn austenitic alloy, have been reported recently.The experimental alloys were made as 50 g argon arc melts using high purity materials and homogenised. Samples were hot- rolled, swaged and machined to 3mm diameter rod, solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised between 1250 °C and 1000 °C and isothermally transformed between 610 °C and 550 °C for 10-18 hr and WQ.

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Precipitation at the transformation interface of pearlite in steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177696 ◽

1990 ◽

Vol 48 (4) ◽

pp. 912-913

Author(s):

F. A. Khalid ◽

D. V. Edmonds

Keyword(s):

Thin Foil ◽

Carbon Steels ◽

Model Alloy ◽

Low Carbon ◽

High Carbon ◽

Growth Interface ◽

Medium Carbon ◽

Interphase Precipitation ◽

Solution Treated ◽

Wide Range

The austenite/pearlite growth interface in a model alloy steel (Fe-1lMn-0.8C-0.5V nominal wt%) is being studied in an attempt to characterise the morphology and mechanism of VC precipitation at the growth interface. In this alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the precipitation of VC at the austenite/ferrite interface, which reaction, termed interphase precipitation, occurs in a number of low- carbon HSLA and microalloyed medium- and high- carbon steels. Some observations of interphase precipitation in microalloyed low- and medium- carbon commercial steels are also reported for comparison as this reaction can be responsible for a significant increase in strength in a wide range of commercial steels.The experimental alloy was made as 50 g argon arc melts using high purity materials and homogenised. Samples were solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised at 1300 °C for 15 min. and isothermally transformed at 620 °C for 10-18hrs. and WQ. Specimens of microalloyed commercial steels were studied in either as-rolled or as- forged conditions. Detailed procedures of thin foil preparation for TEM are given elsewhere.

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Semiconductor growth interface from solution in short-duration low-gravity environment

10.1117/12.351271 ◽

1999 ◽

Cited By ~ 2

Author(s):

Yuko Inatomi ◽

Thomas Kaiser ◽

Peter W. Dold ◽

Klaus-Werner Benz ◽

Kazuhiko Kuribayashi

Keyword(s):

Short Duration ◽

Low Gravity ◽

Growth Interface

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Thermal Analysis of AlGaN/GaN HEMTs Considering Anisotropic And Inhomogeneous Thermal Conductivity

10.21203/rs.3.rs-1064478/v1 ◽

2021 ◽

Author(s):

Yao Li ◽

Zixuan Zheng ◽

Qun Li ◽

Hongbin Pu

Keyword(s):

Thermal Conductivity ◽

Temperature Rise ◽

Power Dissipation ◽

Thermal Characteristics ◽

Maximum Temperature ◽

Base Temperature ◽

Initial Growth ◽

Boltzmann Transport ◽

Growth Interface ◽

Anisotropic Thermal Conductivity

Abstract To examine the differences of thermal characteristics introduced by material thermal conductivity, anisotropic polycrystalline diamond (PCD) and GaN are analyzed based on the accurate model of grain sizes in the directions of parallel and vertical to the interface and an approximate solution of the phonon Boltzmann transport equation. Due to the space-variant grain structures of PCD, the inhomogeneous-anisotropic local thermal conductivity, homogeneous-anisotropic thermal conductivity averaged over the whole layer and the typical values of inhomogeneous-isotropic thermal conductivity are compared with/without anisotropic GaN thermal conductivity. The results show that the considerations of inhomogeneous-anisotropic PCD thermal conductivity and anisotropic GaN thermal conductivity are necessary for the accurate prediction of temperature rise in the GaN HEMT devices, and when ignoring both, the maximum temperature rise is undervalued by over 16 K for thermal boundary resistance (TBR) of 6.5 to 60 m2K/GW at power dissipation of 10 W/mm. Then the dependences of channel temperature on several parameters are discussed and the relations of thermal resistance with power dissipation are extracted at different base temperature. Compared with GaN, SiC and Si substrates, PCD is the most effective heat spreading layer though limited by the grain size at initial growth interface.

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Three Dimensional Effect of Axial Magnetic Field to Suppress Convection in the Solvent of Ge0.98Si0.02 Grown By the Traveling Solvent Method

10.32920/ryerson.14657451 ◽

2021 ◽

Author(s):

Leily Abidi

Keyword(s):

Magnetic Field ◽

Stokes Equations ◽

Axial Magnetic Field ◽

Three Dimensional ◽

Maximum Velocity ◽

Navier Stokes ◽

Growth Interface ◽

Navier Stokes Equations ◽

Solvent Method ◽

Element Technique

A three dimensional numerical simulation of the effect of an axial magnetic field on the fluid flow, heat and mass transfer within the solvent of GE0.98Si0.02 grown by the travelling solvent method is presented. The full steady state Navier-Stokes equations, as well as the energy, continuity and the mass transport equations, were solved numerically using the finite element technique. It is found that a strong convective flow exists in the solvent, which is known to be undesirable to achieve a uniform crystal. An external axial magnetic field is applied to suppress this convection. By increasing the magnetic induction, it is observed that the intensity of the flow at the centre of the crucible reduces at a faster rate than near the wall. This phenomenon creates a stable and flat growth interface and the silicon distribution in the horizontal plane becomes relatively homocentric. The maximum velocity is found to obey a power law with respect to the Hartmann number Umax Ha⁻⁷/⁴

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Three Dimensional Effect of Axial Magnetic Field to Suppress Convection in the Solvent of Ge0.98Si0.02 Grown By the Traveling Solvent Method

10.32920/ryerson.14657451.v1 ◽

2021 ◽

Author(s):

Leily Abidi

Keyword(s):

Magnetic Field ◽

Stokes Equations ◽

Axial Magnetic Field ◽

Three Dimensional ◽

Maximum Velocity ◽

Navier Stokes ◽

Growth Interface ◽

Navier Stokes Equations ◽

Solvent Method ◽

Element Technique

A three dimensional numerical simulation of the effect of an axial magnetic field on the fluid flow, heat and mass transfer within the solvent of GE0.98Si0.02 grown by the travelling solvent method is presented. The full steady state Navier-Stokes equations, as well as the energy, continuity and the mass transport equations, were solved numerically using the finite element technique. It is found that a strong convective flow exists in the solvent, which is known to be undesirable to achieve a uniform crystal. An external axial magnetic field is applied to suppress this convection. By increasing the magnetic induction, it is observed that the intensity of the flow at the centre of the crucible reduces at a faster rate than near the wall. This phenomenon creates a stable and flat growth interface and the silicon distribution in the horizontal plane becomes relatively homocentric. The maximum velocity is found to obey a power law with respect to the Hartmann number Umax Ha⁻⁷/⁴

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Effect of Chemicals on the Microbial Evolution in Foods

Journal of Food Protection ◽

10.4315/0362-028x-67.9.1977 ◽

2004 ◽

Vol 67 (9) ◽

pp. 1977-1990 ◽

Cited By ~ 14

Author(s):

F. DEVLIEGHERE ◽

K. FRANCOIS ◽

K. M. VEREECKEN ◽

A. H. GEERAERD ◽

J. F. VAN IMPE ◽

...

Keyword(s):

Food Product ◽

Microbial Evolution ◽

Microbial Inactivation ◽

Growth Interface ◽

Evolutionary Patterns ◽

Food Ingredients ◽

Microbial Risk Assessment ◽

Meal Preparation ◽

Number Of Microorganisms ◽

Microbial Proliferation

In contrast with most chemical hazardous compounds, the concentration of food pathogens changes during processing, storage, and meal preparation, making it difficult to estimate the number of microorganisms or the concentration of their toxins at the moment of ingestion by the consumer. These changes are attributed to microbial proliferation, survival, and/or inactivation and must be considered when exposure to a microbial hazard is assessed. The number of microorganisms can also change as a result of physical removal, mixing of food ingredients, partitioning of a food product, or cross-contamination (M. J. Nauta. 2002. Int. J. Food Microbiol. 73:297–304). Predictive microbiology, i.e., relating these microbial evolutionary patterns to environmental conditions, can therefore be considered a useful tool for microbial risk assessment, especially in the exposure assessment step. During the early development of the field (late 1980s and early 1990s), almost all research was focused on the modeling of microbial growth over time and the influence of temperature on this growth. Later, modeling of the influence of other intrinsic and extrinsic parameters garnered attention. Recently, more attention has been given to modeling of the effects of chemicals on microbial inactivation and survival. This article is an overview of different applied strategies for modeling the effect of chemical compounds on microbial populations. Various approaches for modeling chemical growth inhibition, the growth–no growth interface, and microbial inactivation by chemicals are reviewed.

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Bandstructure Near Misfit Dislocations in Si Quantum Wells

Microscopy and Microanalysis ◽

10.1017/s1431927600024090 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 794-795

Author(s):

P.E. Batson

Keyword(s):

Quantum Wells ◽

Conduction Band ◽

Electron Mobility ◽

Axial Strain ◽

Strain Relaxation ◽

Local Potential ◽

Misfit Dislocations ◽

High Electron ◽

Strained Si ◽

Growth Interface

High electron mobility structures have been built for several years now using strained silicon layers grown on SixGe(1-x) with x in the 25-40% range. In these structures, a thin layer of silicon is grown between layers of unstrained GeSi alloy. Matching of the two lattices in the plane of growth produces a bi-axial strain in the silicon, splitting the conduction band and providing light electron levels for enhanced mobility. If the silicon channel becomes too thick, strain relaxation can occur by injection of misfit dislocations at the growth interface between the silicon and GeSi alloy. The strain field of these dislocations then gives rise to a local potential variation that limits electron mobility in the strained Si channel. This study seeks to verify this mechanism by measuring the absolute conduction band shifts which track the local potential near the misfit dislocations.

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Nanomolded buried light-scattering (BLiS) back-reflectors using dielectric nanoparticles for light harvesting in thin-film silicon solar cells

EPJ Photovoltaics ◽

10.1051/epjpv/2019011 ◽

2020 ◽

Vol 11 ◽

pp. 2

Author(s):

Derese Desta ◽

Rita Rizzoli ◽

Caterina Summonte ◽

Rui N. Pereira ◽

Arne Nylandsted Larsen ◽

...

Keyword(s):

Solar Cells ◽

Light Scattering ◽

Silicon Nanoparticles ◽

Short Circuit ◽

Spatial Separation ◽

Short Circuit Current ◽

Silicon Solar Cells ◽

Growth Interface ◽

Inverted Pyramid ◽

Back Reflector

The article presents a nanoparticle-based buried light-scattering (BLiS) back-reflector design realized through a simplified nanofabrication technique for the purpose of light-management in solar cells. The BLiS structure consists of a flat silver back-reflector with an overlying light-scattering bilayer which is made of a TiO2 dielectric nanoparticles layer with micron-sized inverted pyramidal cavities, buried under a flat-topped silicon nanoparticles layer. The optical properties of this BLiS back-reflector show high broadband and wide angular distribution of diffuse light-scattering. The efficient light-scattering by the buried inverted pyramid back-reflector is shown to effectively improve the short-circuit-current density and efficiency of the overlying n-i-p amorphous silicon solar cells up to 14% and 17.5%, respectively, compared to the reference flat solar cells. A layer of TiO2 nanoparticles with exposed inverted pyramid microstructures shows equivalent light scattering but poor fill factors in the solar cells, indicating that the overlying smooth growth interface in the BLiS back-reflector helps to maintain a good fill factor. The study demonstrates the advantage of spatial separation of the light-trapping and the semiconductor growth layers in the photovoltaic back-reflector without sacrificing the optical benefit.

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