scholarly journals Impact of Surface Roughness on Ion-Surface Interactions Studied with Energetic Carbon Ions 13C+ on Tungsten Surfaces

2019 ◽  
Vol 4 (1) ◽  
pp. 29 ◽  
Author(s):  
Maren Hellwig ◽  
Martin Köppen ◽  
Albert Hiller ◽  
Hans Koslowski ◽  
Andrey Litnovsky ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Angular Distribution ◽  
Surface Morphology ◽  
High Vacuum ◽  
Surface Interactions ◽  
Surface Interaction ◽  
Ultra High Vacuum ◽  
Nuclear Reaction Analysis ◽  
Angle Of Incidence ◽  
Carbon Ions

The effect of surface roughness on angular distributions of reflected and physically sputtered particles is investigated by ultra-high vacuum (UHV) ion-surface interaction experiments. For this purpose, a smooth (R a = 5.9 nm) and a rough (R a = 20.5 nm) tungsten (W) surface were bombarded with carbon ions 13C+ under incidence angles of 30 ∘ and 80 ∘ . Reflected and sputtered particles were collected on foils to measure the resulting angular distribution as a function of surface morphology. For the qualitative and quantitative analysis, secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) were performed. Simulations of ion-surface interactions were carried out with the SDTrimSP (Static Dynamic Transport of Ions in Matter Sputtering) code. For rough surfaces, a special routine was derived and implemented. Experimental as well as calculated results prove a significant impact of surface roughness on the angular distribution of reflected and sputtered particles. It is demonstrated that the effective sticking of C on W is a function of the angle of incidence and surface morphology. It is found that the predominant ion-surface interaction process changes with fluence.

Nucleation and Growth of Polycrystalline Silicon Films in an Ultra high Vacuum Rapid Thermal Chemical Vapor Deposition Reactor Using Disilane and Hydrogen

1994 ◽  
Vol 343 ◽  
Author(s):  
Katherine E. Violette ◽  
Mehmet C. Öztürk ◽  
Gari Harris ◽  
Mahesh K. Sanganeria ◽  
Archie Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Roughness ◽  
Chemical Vapor Deposition ◽  
Surface Morphology ◽  
Vapor Deposition ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Chemical Vapor Deposition Reactor ◽  
Thermal Chemical Vapor Deposition

A study of Si nucleation and deposition on SiO2 was performed using disilane and hydrogen in an ultra high vacuum rapid thermal chemical vapor deposition reactor in pressure and temperature ranges of 0.1 – 1.5 Torr and 625 – 750°C. The film analysis was carried out using scanning electron microscopy, transmission electron microscopy and atomic force microscopy. At lower pressures, an incubation time exists which leads to a retardation in film nucleation. At 750°C, the incubation time is 10s at 0.1 Torr and decreases to less than Is at 1.5 Torr. The nuclei grow and form three dimensional islands on S1O2, and as they coalesce, result in a rough surface morphology. At higher pressures, the inherent selectivity is lost resulting in a higher nucleation density and smoother surface morphology. For ˜ 2000 Å thick films, the root-mean-square surface roughness at 750ÅC ranges from 110Å at 0.1 Torr to 40Å at 1.5 Torr. Temperature also strongly influences the film structure through surface mobility and grain growth. At 1 Torr, the roughness ranges from 3Å at 625°C to 60Å at 750°C. The grain structure at 625°C/1Torr appears to be amorphous, whereas at 750°C the structure is columnar. The growth rate at 625°C/1.5 Torr is 1200 Å/min provides a surface roughness on the order of atomic dimensions which is comparable to or better than amorphous silicon deposited in LPCVD furnaces.

Ion-Surface Interactions During Epitaxy

1990 ◽  
Vol 201 ◽  
Author(s):  
S. A. Barnett ◽  
C.-H. Choi ◽  
R. Kaspi
Keyword(s):  
High Vacuum ◽  
Surface Interactions ◽  
Epitaxial Films ◽  
Ultra High Vacuum ◽  
Semiconductor Materials ◽  
Layer By Layer ◽  
Crystalline Perfection ◽  
Ion Energies ◽  
Miscibility Gaps ◽  
Deposition Techniques

AbstractRecent work on low-energy ion-assisted deposition of epitaxial films is reviewed. Much of the interest in this area has centered on the use of very low ion energies (∼ 25 eV) and high fluxes (> 1 ion per deposited atom) obtained using novel ion-assisted deposition techniques. These methods have been applied in ultra-high vacuum, allowing the preparation of high-purity semiconductor materials. The following ion-surface interaction effects during epitaxy are discussed: improvements in crystalline perfection during low temperature epitaxy, ion damage effects, improved homogeneity and properties in III-V alloys grown within miscibility gaps, and changes in nucleation mechanism from Stranski-Krastanov to layer-by-layer.

Relationship Between Graded Layer Structures and Defects in Silicon-Germanium Virtual Substrates

2000 ◽  
Vol 648 ◽  
Author(s):  
Kazuki Mizushima ◽  
Ichiro Shiono ◽  
Kenji Yamaguchi ◽  
Naoki Muraki
Keyword(s):  
Surface Roughness ◽  
Silicon Germanium ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Optimum Number ◽  
Threading Dislocation ◽  
Typical Sample ◽  
Dislocation Densities

AbstractSilicon-germanium virtual substrates have been synthesized by low-pressure chemical vapor deposition. We obtained threading dislocation densities ranging from 105 to 106 cm−2, surface roughness ranging from 1.5 to 4 nm, and also cross-hatch pattern densities, depending on the grading rate and top layer germanium composition. For the typical sample, which has a linear-graded structure with a grading rate of 20%/[µm, and germanium composition of 30 % at the top layer, we obtained dislocation densities of about 106 cm−2 and root mean squared surface roughness of about 3 nm. The obtained dislocation densities are equivalent with the virtual substrates synthesized by ultra-high vacuum system. On the other hand the surface roughness is superior to the typical reported values. In this study three kinds of structures, i.e. linear-graded, stepwise, and graded-step structures, were considered. We found the defects are effectively reduced by introduction of an optimum number of steps in the graded layer.

Progression of the Surface Roughness of N+ Silicon Epitaxial Films as Analyzed by AFM

1995 ◽  
Vol 399 ◽  
Author(s):  
S. John ◽  
E. J. Quinones ◽  
B. Ferguson ◽  
K. Pacheco ◽  
C. B. Mullins ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Vacuum ◽  
Film Surface ◽  
Chemical Vapor ◽  
Epitaxial Films ◽  
Ultra High Vacuum ◽  
Phosphorus Segregation ◽  
Surface Mobility ◽  
Partial Pressures ◽  
Effects Of Ph

ABSTRACTWe report on the morphology of heavily phosphorous doped silicon films grown by ultra high vacuum chemical vapor deposition at temperatures of ∼550° C. The effects of PH3 on epitaxial films have been examined for silicon deposited using SiH4 and Si2H6. It is found that films grown using silane experience an increase in surface roughness with increasing phosphine partial pressure. AFM and RHEED studies indicate 3-D growth. As epitaxy progresses, it is believed that phosphorus segregation on the growing film surface greatly diminishes the adsorption and surface mobility of the silicon bearing species. Initial Si deposition results in a pitted surface, but as growth advances and the phosphorus coverage increases, growth within the pits decreases the surface roughness. In contrast to SiH4, it is found that Si2H6 provides excellent quality, smooth films even at high PH3 partial pressures.

Synthesis of Ti-Zr-V Non-Evaporable Getter Thin Films Grown on Al Alloy and CuCrZr Alloy

2017 ◽  
Vol 730 ◽  
pp. 87-94 ◽  
Author(s):  
Ling Hui Wu ◽  
Chia Mu Cheng ◽  
Chin Shueh ◽  
Che Kai Chan ◽  
Chin Chun Chang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Defects ◽  
Substrate Surface ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Al Alloy ◽  
Metallic State ◽  
Vacuum Chambers ◽  
Nanocrystalline Structures ◽  
Surface Morphologies

The Ti-Zr-V non-evaporable getter (NEG) films were grown on Aluminum (Al) alloy and CuCrZr alloy, which can be used to fabricate the vacuum chambers in the ultra-high vacuum status. The Al alloy and CuCrZr alloy samples with different surface roughness were prepared by the different manufacturing methods. We studied whether the behavior and the microstructure of the Ti-Zr-V getter films are influence by the surface roughness of the substrate. The surface morphologies of Ti-Zr-V NEG films appear distinct and the growth of the films follows the nature of the substrate surface. The Ti-Zr-V films have nanocrystalline structures and the grain sizes of the films become slightly larger with increasing the surface smoothness. In addition, it was found that the reduction of the Ti-Zr-V NEG films to the metallic state was affected by presence of surface defects on the films. The surface defects should result from the existence of micro-pores, pockmarks, and micro-cracks on the original substrate, which produced from the manufacturing process.

Effect of substrate hardness and surface roughness on the film formation of aerosol-deposited ceramic films

2017 ◽  
Vol 10 (04) ◽  
pp. 1750045 ◽  
Author(s):  
Michael Schubert ◽  
Manuel Hahn ◽  
Jörg Exner ◽  
Jaroslaw Kita ◽  
Ralf Moos
Keyword(s):  
Surface Roughness ◽  
Film Formation ◽  
Substrate Surface ◽  
High Vacuum ◽  
High Hardness ◽  
Aerosol Deposition ◽  
Ultra High Vacuum ◽  
Ceramic Substrates ◽  
Ceramic Films ◽  
Substrate Hardness

The aerosol deposition (AD) method is a novel ceramic coating technique that allows manufacturing of dense ceramic films at room temperature directly from ceramic powders without any high temperature sintering steps and without expensive (ultra) high vacuum processes. The deposition mechanism can be separated into two stages: the creation of an anchor layering and the subsequent film formation. Step one involves an initial plastic deformation of the substrate surface by the first impacting particles. Especially in the first stage, substrate properties affect the deposition and determine the dominant bonding mechanism. Ductile substrates can be expected to give strong film anchoring, whereas high hardness substrates might require higher particle velocities to form adhering layers. In this study, the influence of the substrate hardness in combination with the surface roughness on the deposition was investigated. Four ceramic substrates (two types of Al2O3, sapphire, and LTCC) with different hardness and surface roughness were coated with Al2O3 in order to study the formation of an anchoring layer and their effect on the deposition rate. As a result, no anchoring layer was found on the hard ceramic substrates.

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