Growth and Properties of SiC On-Axis Homoepitaxial Layers

2010 ◽  
Vol 645-648 ◽  
pp. 83-88 ◽  
Author(s):  
Jawad ul Hassan ◽  
Peder Bergman ◽  
Justinas Palisaitis ◽  
Anne Henry ◽  
Patrick J. McNally ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Growth Parameters ◽  
Substrate Surface ◽  
High Surface ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
High Quality ◽  
Surface Damages ◽  
Homoepitaxial Layers

Homoepitaxial growth has been performed on 3” Si-face on-axis 4H–SiC substrates using standard gas system in a horizontal Hot-wall chemical vapor deposition system. Substrate surface damages are found to act as preferential nucleation sites for 3C inclusions also, the surface morphology after in-situ etching is found to largely influence the polytype stability in the epilayer. Different in-situ etching conditions were studied where Si-rich conditions are found to be better. Growth parameters and starting growth conditions are refined to obtain stable polytype in the epilayer. High quality homoepitaxial layers with 100% 4H–SiC are obtained on 3” substrates. Different optical and structural techniques are used to characterize the layers and to understand the growth mechanisms. The layers are found to be of high quality and no epitaxial defects typically found on off-axis epitaxial layers are observed. A high surface roughness is observed in these layers, however higher growth rate significantly lowers the surface roughness without affecting the polytype stability in the epilayer.

CVD Heteroepitaxial Growth of 3C-SiC on 4H-SiC (0001) Substrates

2012 ◽  
Vol 717-720 ◽  
pp. 189-192 ◽  
Author(s):  
Xun Li ◽  
Stefano Leone ◽  
Sven Andersson ◽  
Olof Kordina ◽  
Anne Henry ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Growth Parameters ◽  
Single Domain ◽  
Heteroepitaxial Growth ◽  
High Quality ◽  
Grown Layer ◽  
Afm Analysis ◽  
Background Doping ◽  
Nm Range

This study has been focused on 3C-SiC epitaxial growth on 4H-SiC (0001) on-axis substrates using the standard CVD chemistry. Several growth parameters were investigated, including growth temperature, in-situ etching process and C/Si ratio. High quality single domain 3C epilayers could be obtained around 1350 °C, with propane present during pre-growth etching and when the C/Si ratio was equal to 1. The best grown layer is 100% 3C-SiC and single domain. The net n-type background doping is around 2x1016 cm-3. The surface roughness of the layers from AFM analysis is in the 3 to 8 nm range on a 50x50 μm2 area.

scholarly journals High-quality net shape geometries from additively manufactured parts using closed-loop controlled ablation with ultrashort laser pulses

2020 ◽  
Vol 9 (1-2) ◽  
pp. 101-110 ◽  
Author(s):  
Daniel Holder ◽  
Artur Leis ◽  
Matthias Buser ◽  
Rudolf Weber ◽  
Thomas Graf
Keyword(s):  
Surface Roughness ◽  
Closed Loop ◽  
High Surface ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Minimum Thickness ◽  
High Quality ◽  
Surface Optical ◽  
The Individual ◽  
Ultrashort Laser

AbstractAdditively manufactured parts typically deviate to some extent from the targeted net shape and exhibit high surface roughness due to the size of the powder grains that determines the minimum thickness of the individual slices and due to partially molten powder grains adhering on the surface. Optical coherence tomography (OCT)-based measurements and closed-loop controlled ablation with ultrashort laser pulses were utilized for the precise positioning of the LPBF-generated aluminum parts and for post-processing by selective laser ablation of the excessive material. As a result, high-quality net shape geometries were achieved with surface roughness, and deviation from the targeted net shape geometry reduced by 67% and 63%, respectively.

Observations on the Growth of YBa2Cu3O7 Thin Films at Very High Laser Fluences

1995 ◽  
Vol 388 ◽  
Author(s):  
Rand R. Biggers. ◽  
M. Grant Norton ◽  
I. Maartense ◽  
T.L. Peterson ◽  
E. K. Moser ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Organic Chemical ◽  
High Fluences ◽  
Laser Fluences ◽  
High Laser ◽  
High Laser Fluences ◽  
Very High

AbstractThe pulsed-laser deposition (PLD) technique utilizes one of the most energetic beams available to form thin films of the superconducting oxide YBa2Cu3O7 (YBCO). IN this study we examine the growth of YBCO at very high laser fluences (25 to 40 J/cm2); a more typical fluence for PLD would be nearer to 3 J/cm2. the use of high fluences leads to unique film microstructures which, in some cases, appear to be related to the correspondingly higher moveabilities of the adatoms. Films grown on vicinal substrates, using high laser fluences, exhibited well-defined elongated granular morphologies (with excellent transition temperature, Tc, and critical current density, Jc). Films grown on vicinal substrates using off-axis magnetron sputtering, plasma-enhanced metal organic chemical vapor deposition (PE-MOCVD), or PLD at more typical laser fluences showed some similar morphologies, but less well-defined. Under certain growth conditions, using high laser fluences with (001) oriented substrates, the YBCO films can exhibit a mixture of a- and c-axis growth where both crystallographic orientations nucleate on the substrate surface at the same time, and grow in concert. the ratio of a-axis oriented to c-axis oriented grains is strongly affected by the pulse repetition rate of the laser.

Surface and Sub-Surface Integrity of Ultra- Machined BK7 Using Fine and Coarse Grained Diamond Wheels

2007 ◽  
Vol 359-360 ◽  
pp. 234-238 ◽  
Author(s):  
Qing Liang Zhao ◽  
Bo Wang ◽  
Ekkard Brinksmeier ◽  
Otmann Riemer ◽  
Kai Rickens ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
High Surface ◽  
Coarse Grained ◽  
Nanometer Scale ◽  
Grinding Wheels ◽  
Fine Grained ◽  
Optical Glasses ◽  
Diamond Grinding ◽  
Surface Damages

This paper aims to evaluate the surface and sub-surface integrity of optical glasses which were correspondingly machined by coarse and fine-grained diamond grinding wheels on Tetraform ‘C’ and Nanotech 500FG. The experimental results show that coarse-grained diamond grinding wheels are capable of ductile grinding of optical glasses with high surface and sub-surface integrity. The surface roughness values are all in nanometer scale and the sub-surface damages are around several micros in depth, which is comparative to those machined by fine-grained diamond wheels.

Development of Vertical 3×2〞LPCVD System for Fast Epitaxial Growth on 4H-SiC

2012 ◽  
Vol 717-720 ◽  
pp. 105-108 ◽  
Author(s):  
Wan Shun Zhao ◽  
Guo Sheng Sun ◽  
Hai Lei Wu ◽  
Guo Guo Yan ◽  
Liu Zheng ◽  
...  
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Epitaxial Growth ◽  
Vapor Deposition ◽  
Growth Process ◽  
Chemical Vapor ◽  
Low Pressure ◽  
High Quality ◽  
Pressure Chemical ◽  
Homoepitaxial Layers

A vertical 3×2〞low pressure chemical vapor deposition (LPCVD) system has been developed to realize fast epitaxial growth of 4H-SiC. The epitaxial growth process was optimized and it was found that the growth rate increases with increasing C/Si ratio and tends to saturate when C/Si ratio exceeded 1. Mirror-like thick 4H-SiC homoepitaxial layers are obtained at 1500 °C and C/Si ratio of 0.5 with a growth rate of 25 μm/h. The minimum RMS roughness is 0.20 nm and the FWHM of rocking curves of epilayers grown for 1 hour and 2 hours are 26.2 arcsec and 32.4 arcsec, respectively. These results indicate that high-quality thick 4H-SiC epilayers can be grown successfully on the off-orientation 4H-SiC substrates.

ANTIPHASE DOMAIN FREE EPITAXIAL GROWTH OF GaAs ON (100)Ge

1985 ◽  
Vol 56 ◽  
Author(s):  
Y. Shinoda ◽  
Y. Ohmachi
Keyword(s):  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Antiphase Domain ◽  
Epitaxial Layers ◽  
High Quality ◽  
Thermal Etching ◽  
Domain Structures ◽  
Homoepitaxial Layers

AbstractHigh-quality single domain GaAs epitaxial layers were successfully grown on (100)Ge substrates. Growth was carried out using conventional metalorganic chemical vapor deposition at atmospheric pressure. Antiphase domain free GaAs epitaxial layers were obtained by thermal etching of the Ge surface just prior to growth. Mosaic surface morphology and antiphase boundaries characteristic of domain structures were completely absent in epi-layers following thermal etching. Photoluminescence revealed that domain free epi-layers exhibited characteristics comparable to those of GaAs homoepitaxial layers.

Surface Properties and Cell Response of Bioactive Thermally Grown TiO2 Nanofibers

2014 ◽  
Vol 575 ◽  
pp. 219-222
Author(s):  
A.W. Tan ◽  
Belinda Pingguan-Murphy ◽  
Roslina Ahmad ◽  
Sheikh Akbar
Keyword(s):  
Surface Roughness ◽  
Articular Chondrocytes ◽  
Substrate Surface ◽  
Control Sample ◽  
Degree Of Crystallinity ◽  
Crystallographic Structure ◽  
Cartilage Growth ◽  
Bovine Articular Chondrocytes

Titania nanofiber (TiO2 NFs) arrays were fabricated in situ on a Ti-6Al-4V substrate by an oxidation process. Their surface morphology, crystallographic structure, surface roughness and wettability were characterized, as well as their in vitro interaction with bovine articular chondrocytes at different time points. Results showed that TiO2 NFs possessed greater surface roughness, hydrophilicity and degree of crystallinity. The in vitro cell studies revealed that TiO2 NFs substrate triggers enhanced cell adhesion, proliferation and extracellular matrix (ECM) formation compared to the untreated control sample. These results showed that chondrocytes have an affinity to the nanofibrous substrate surface and thus we suggest that such surfaces are suited to be used as an implant designed for cartilage growth.

scholarly journals Phosphorous Doping of Microcrystalline CVD Diamond Using Modified Conditions

2007 ◽  
Vol 1039 ◽  
Author(s):  
Ken Haenen ◽  
Andrada Lazea ◽  
Vincent Mortet ◽  
Jan D'Haen ◽  
Peter Geithner ◽  
...  
Keyword(s):  
Microwave Plasma ◽  
Growth Parameters ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Cvd Diamond ◽  
Growth Conditions ◽  
Diamond Surfaces ◽  
Cvd Growth ◽  
Oriented Polycrystalline ◽  
Electron Back Scattered Diffraction

AbstractPhosphorous-doping of predominantly (110) oriented polycrystalline CVD diamond films is presented. Incorporation of phosphorous into the diamond grains was accomplished by using novel microwave plasma enhanced chemical vapor deposition (MW PE CVD) growth conditions. The substitutional nature of the phosphorous atom was confirmed by applying the quasi-steady-state photocurrent technique (PC) and cathodoluminescence (CL) measurements at low temperature. Topographical information and the relation between substrate and P-doped film grain orientation was obtained with scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The optimized growth parameters for P-doped layers on (110) oriented polycrystalline diamond differ substantially from the standard conditions reported in literature for P-doping of single crystalline (111) and (100) oriented diamond surfaces.

Application of In Situ 3D Computed Tomography during PVT Growth of 4H-SiC for the Study of Source Material Consumption under Varying Growth Conditions

2016 ◽  
Vol 858 ◽  
pp. 49-52 ◽  
Author(s):  
P.J. Wellmann ◽  
Lars Fahlbusch ◽  
Michael Salamon ◽  
Norman Uhlmann
Keyword(s):  
Growth Parameters ◽  
Growth Conditions ◽  
Source Material ◽  
Gas Pressure ◽  
Inert Gas ◽  
Material Surface ◽  
Growth Interface ◽  
Axial Temperature ◽  
The Stability

2D and 3D in-situ X-ray visualization was applied to study the behavior of the SiC source material during PVT growth under various growth conditions. Experiments were carried out in two growth chambers for the growth of 3 inch and 4 inch crystals. Growth parameters were varied in the gas room in terms of axial temperature and inert gas pressure. The study addresses the stability of the SiC source material surface. It is shown that a higher inert gas pressure (e.g. 25 mbar) inhibits an unintentional upward evolution of the SiC feedstock that interferes with the crystal growth interface. The latter is related to a suppression of a pronounced recrystallization inside the SiC source. For a low inert gas pressure (e.g. 10 mbar) it is concluded that the axial temperature gradient inside the source material needs to be decreased to less than ca. 10 K/cm.

Development of Homoepitaxially Grown GaN Thin Film Layers on Freestanding Bulk m-plane Substrates by Metalorganic Chemical Vapor Deposition (MOCVD)

2007 ◽  
Vol 1040 ◽  
Author(s):  
Vibhu Jindal ◽  
James Grandusky ◽  
Neeraj Tripathi ◽  
Mihir Tungare ◽  
Fatemeh Shahedipour-Sandvik ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Growth Rates ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Structural Defects ◽  
Lateral Growth ◽  
High Quality ◽  
Metalorganic Chemical

AbstractHigh quality homoepitaxial growth of m-plane GaN films on freestanding m-plane HVPE GaN substrates has been performed using metalorganic chemical vapor deposition. For this a large growth space was studied. Large areas of no-nucleation along with presence of high density of defects were observed when layers were grown under growth conditions for c-plane GaN. It is believed that these structural defects were in large part due to the low lateral growth rates as well as unequal lateral growth rates in a- and c- crystallographic directions. To achieve high quality, fully coalesced epitaxial layers, growth conditions were optimized with respect to growth temperature, V/III ratios and reactor pressure. Higher growth temperatures led to smoother surfaces due to increased surface diffusion of adatoms. Overall, growth at higher temperature and lower V/III ratio decreased the surface roughness and resulted in better optical properties as observed by photoluminescence. Although optimization resulted in highly smooth layers, some macroscopic defects were still observed on the epi-surface as a result of contamination and subsurface damage remaining on bulk substrates possibly due to polishing. Addition of a step involving annealing of the bulk substrate under H2: N2 environment, prior to growth, drastically reduced such macroscopic defects.

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