Surface Morphology Improvement and Repeatable Doping Characterization of 4H-SiC Epitaxy Grown on 4° Off-Axis 4H-SiC Wafers

2009 ◽  
Vol 615-617 ◽  
pp. 423-426 ◽  
Author(s):  
Swapna G. Sunkari ◽  
Hrishikesh Das ◽  
Carl Hoff ◽  
Yaroslav Koshka ◽  
Janna R. B. Casady ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Surface ◽  
Process Conditions ◽  
Power Devices ◽  
Low Loss ◽  
High Surface Quality ◽  
Non Destructive ◽  
Koh Etching

4H Silicon Carbide (4H-SiC) has a great potential for low-loss power devices due to its superior electrical properties. However, the increase in demand for the power devices requires high quality SiC substrates and epitaxial layers. Mercury probe Capacitance Voltage (Hg CV) measurement is a well known procedure to characterize epi layers grown on SiC substrates, due to its non-destructive technique. However, careful calibration of the tool is very important for repeatable and accurate measurements. Here we present very close repeatability of Hg CV within 2.4% (standard deviation 0.7%), between different Solid State Measurements (SSM) setups compared with Ni Schottky (NiS) CV. In addition to growing uniformly doped epi layers, high surface quality of the epi layer is also needed for improved device performance. Improved process conditions resulted in a smooth epi with a surface roughness Ra 1.2 nm for a 6 µm thick epi layer. Molten Potassium Hydroxide (KOH) etching analysis also revealed a significant correlation between the surface roughness and epi defects.

The Use of Metallographic and SEM Analysis for Characterization of Sidewall Surfaces in MEMS Devices with DRIE Processing

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000992-001007
Author(s):  
Lee Levine ◽  
Robert Dean ◽  
Colin Stevens ◽  
Samuel Lawrence
Keyword(s):  
Surface Roughness ◽  
Surface Condition ◽  
Sem Analysis ◽  
Process Conditions ◽  
Mems Devices ◽  
Performance Requirements ◽  
Sem Imaging ◽  
Microscopy Techniques

The use of Bosch process Deep Reactive Ion Etch (DRIE) processing for manufacturing MEMS and MOEMS devices requiring high aspect ratio (depth/width) trenches has become commonplace. However, process conditions (etch rate, process parameters etc.) have a significant effect on the surface quality of the trench sidewalls. For many device types [1] (grates, waveguides) surface condition of the sidewall can have a large impact on the functionality of the device and therefore must be controlled to achieve performance requirements. Optical microscopy techniques are not capable of the depth of focus and resolution necessary to adequately control processing within deep trenches where surface roughness of < 10nm may be required. Scanning Electron Microscopy (SEM) is capable of this resolution, but even SEM is incapable of determining surface roughness within the deep trenches. Metallographic techniques, mounting and polishing a sample to reveal a section view through the trench, along with SEM, to image and measure the surface roughness is a requirement. An experiment was designed, using etch parameters to vary the DRIE recipe, and then cross sectioning and SEM imaging of the devices were performed. The purpose of the experiment was to quantify the effect of the DRIE recipe on the sidewall surface roughness within the trench, and to demonstrate the use of metallographic techniques with SEM to accomplish this goal.

scholarly journals Post-Processing and Surface Characterization of Additively Manufactured Stainless Steel 316L Lattice: Implications for BioMedical Use

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1376
Author(s):  
Alex Quok An Teo ◽  
Lina Yan ◽  
Akshay Chaudhari ◽  
Gavin Kane O’Neill
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Surface Characterization ◽  
High Surface ◽  
Surface Characteristics ◽  
Post Processing ◽  
Stainless Steel 316L ◽  
Processing Methods ◽  
Particulate Debris

Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the customisation of structure and surface characteristics; there is little guidance for the post-processing of these metals. We carried out this study to ascertain the effects of various combinations of post-processing methods on the surface of an additively manufactured stainless steel 316L lattice. We also characterized the nature of residual surface particles found after these processes via energy-dispersive X-ray spectroscopy. Finally, we measured the surface roughness of the post-processing lattices via digital microscopy. The native lattices had a predictably high surface roughness from partially molten particles. Sandblasting effectively removed this but damaged the surface, introducing a peel-off layer, as well as leaving surface residue from the glass beads used. The addition of either abrasive polishing or electropolishing removed the peel-off layer but introduced other surface deficiencies making it more susceptible to corrosion. Finally, when electropolishing was performed after the above processes, there was a significant reduction in residual surface particles. The constitution of the particulate debris as well as the lattice surface roughness following each post-processing method varied, with potential implications for clinical use. The work provides a good base for future development of post-processing methods for additively manufactured stainless steel.

scholarly journals Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy

Machines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 75
Author(s):  
Nikolaos E. Karkalos ◽  
Panagiotis Karmiris-Obratański ◽  
Szymon Kurpiel ◽  
Krzysztof Zagórski ◽  
Angelos P. Markopoulos
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Process Parameters ◽  
Manufacturing Industry ◽  
High Surface ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
High Surface Quality ◽  
Trochoidal Milling

Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness.

Long range, non-destructive characterization of GaN substrates for power devices

2019 ◽  
Vol 506 ◽  
pp. 178-184 ◽  
Author(s):  
J.C. Gallagher ◽  
T.J. Anderson ◽  
L.E. Luna ◽  
A.D. Koehler ◽  
J.K. Hite ◽  
...  
Keyword(s):  
Long Range ◽  
Power Devices ◽  
Non Destructive ◽  
Non Destructive Characterization

The real-time rendering of subdivision surfaces using hardware tessellation

2015 ◽  
Vol 57 (5) ◽  
Author(s):  
Matthias Nießner
Keyword(s):  
Real Time ◽  
High Surface ◽  
Subdivision Surfaces ◽  
High Surface Quality ◽  
Industry Standard ◽  
Desktop Computers ◽  
Computational Budget ◽  
Film Productions ◽  
Novel Algorithms

AbstractIn the last decade, computer-generated images have become a vital and integral part of our everyday lives. The quality of these images depends considerably on the geometric representation of the underlying virtual 3D environments. Subdivision surfaces, one such representation, have been found to be very useful due to their unique geometric properties. These properties led to the adaptation of subdivision surfaces as a movie industry standard for modeling 3D geometry, making subdivision surfaces indispensable in today's film productions. However, despite the high surface quality of subdivision surfaces, the complexity of underlying calculations requires a significant computational budget. In this thesis, we address this problem and propose novel algorithms to accelerate the evaluation of subdivision surfaces by several orders of magnitude. This enables the rendering of high-quality movie content on commercially available desktop computers within only a few milliseconds, opening up the possibility of using subdivision surfaces in real-time applications (e. g., video games). The results of this work have been made publicly available in Pixar's open source initiative

scholarly journals Facile, non-destructive characterization of 2d photonic crystals using UV-vis-spectroscopy

2018 ◽  
Vol 20 (6) ◽  
pp. 4340-4346 ◽  
Author(s):  
V. Schöps ◽  
B. Lenyk ◽  
T. Huhn ◽  
J. Boneberg ◽  
E. Scheer ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Dry Etching ◽  
Dielectric Substrates ◽  
Size Evolution ◽  
Vis Spectroscopy ◽  
Radiative Losses ◽  
Non Destructive ◽  
Non Destructive Characterization

The quality of particle monolayers and size evolution of their particles during dry etching can be monitored by radiative losses of photonic modes into dielectric substrates.

Development of polymer abrasive medium for nanofinishing of microholes on surgical stainless steel using abrasive flow finishing process

2019 ◽  
Vol 234 (3) ◽  
pp. 355-370 ◽  
Author(s):  
Sachin Singh ◽  
M Ravi Sankar
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
High Surface ◽  
Machining Process ◽  
Abrasive Medium ◽  
Finishing Process ◽  
Drug Eluting ◽  
Finishing Processes ◽  
Abrasive Flow Finishing

The finishing operation completes the manufacturing cycle of a component. Depending on the level of finish (micro and nano) required on the component surface, different finishing processes are employed. Several components employed in medical, automotive and chemical industries use different types of passages for the flow of fluid. The surface roughness of such passages decides the functionality of the component. Drug-eluting stents are one of the recent advancements in the medical industry. They possess microholes for release of the drugs to the point of cure. Microholes are mostly fabricated by thermal-based micromachining processes that generate metallurgically destroyed surface layers with high surface roughness. Later, these are polished using chemical or electrochemical polishing techniques, which chemically destroy the quality of the surface. These metallurgically and chemically modified (destroyed/changed) rough surfaces on the microhole wall can cause contamination of the drug. So in this article, microholes of diameter 850 ± 30 µm are fabricated in surgical stainless steel (SS 316L) workpieces using the electric discharge micromachining process. Machined microholes are finished by employing a non-traditional finishing process called the abrasive flow finishing process. Instead of using a commercially available expensive abrasive flow finishing medium, the economic medium is fabricated in-house, and its rheological study is carried out. Machining process produces microholes with a surface roughness of about 1.40 ± 0.10 µm. Later, by finishing of microholes with the abrasive flow finishing process, the surface roughness is reduced to 150 nm (percentage surface roughness improvement of about 88.53%). Therefore, the abrasive flow finishing process is a viable alternative to chemical-based polishing processes as it removes the recast layer and achieves nanosurface roughness.

scholarly journals Ultra-thin films for plasmonics: a technology overview

2015 ◽  
Vol 4 (3) ◽  
Author(s):  
Radu Malureanu ◽  
Andrei Lavrinenko
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Support Surface ◽  
New Materials ◽  
Infra Red ◽  
Plasmon Polaritons ◽  
Plasmon Propagation ◽  
Made In

AbstractUltra-thin films with low surface roughness that support surface plasmon-polaritons in the infra-red and visible ranges are needed in order to improve the performance of devices based on the manipulation of plasmon propagation. Increasing amount of efforts is made in order not only to improve the quality of the deposited layers but also to diminish their thickness and to find new materials that could be used in this field. In this review, we consider various thin films used in the field of plasmonics and metamaterials in the visible and IR range. We focus our presentation on technological issues of their deposition and reported characterization of film plasmonic performance.

Research of Grinding Material Tools by Modern Grinding Wheels

2013 ◽  
Vol 581 ◽  
pp. 211-216 ◽  
Author(s):  
Jiří Čop ◽  
Imrich Lukovics
Keyword(s):  
Boron Nitride ◽  
Surface Quality ◽  
High Surface ◽  
Cubic Boron Nitride ◽  
High Accuracy ◽  
Grinding Wheels ◽  
Cutting Depth ◽  
High Surface Quality ◽  
Materials Used

This research paper focuses on grinding of materials used for tools (100Cr6 (CSN 4 14109), X210Cr12 ( CSN 4 19436) and epoxy resin) using grinding wheels from cubic boron nitride and diamond. The disadvantage of grinding of difficult-to-machine materials is higher wear of grinding wheels. The modern grinding wheels are able to achieve high accuracy of dimensions and high surface quality with a smaller wear of grinding wheels then grinding wheels from conventional materials. Correctly selected technological conditions are one of the most important matters to achieve the required surface quality. The main aim of this research is to determine the influence of technological conditions to quality of surface after planar grinding. The research determines the influence of the grain type of grinding wheels, feed rate and cutting depth on the quality of functional surfaces.

Nondestructive Characterization of GaN Films Grown at Low and High Temperatures

1999 ◽  
Vol 591 ◽  
Author(s):  
C.H. Yana ◽  
H.W. Yao ◽  
J.M. Van Hove ◽  
A.M. Wowchak ◽  
P.P. Chow ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Temperatures ◽  
Sapphire Substrates ◽  
Wurtzite Crystal Structure ◽  
Phonon Spectra ◽  
Scattering Geometry ◽  
Back Scattering ◽  
Nondestructive Characterization

ABSTRACTGaN films grown on GaAs and sapphire substrates by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) at both low and high temperatures (LT and HT) were characterized by Raman scattering and variable angle spectroscopic ellipsometry (VASE). Optical phonon spectra of GaN films are obtained through back-scattering geometry. Crystal quality of these films was qualitatively examined using phonon line-width. Phonon spectra showed that the HT GaN has wurtzite crystal structure, while LT GaN and GaN/GaAs have cubic-like structures. Thickness nonuniformity and defect-related absorption can be characterized by pseudo dielectric functions directly. Surface roughness also can be determined by using an effective-medium approximation (EMA) over-layer in a VASE analysis. Anisotropic optical constants of GaN, both ordinary and extraordinary, were obtained in the spectral range of 0.75 to 6.5 eV with the consideration of surface roughness, through the small and large angles of incidence, respectively. The film thickness of the GaN was accurately determined via the analysis as well.

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