Fractal Dimension and Multifractal Spectra of INGAN/GAN Self-Assembled Quantum Dots Films

2008 ◽  
Author(s):  
K. T. Lam
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Fractal Dimension ◽  
High Speed ◽  
Surface Characterization ◽  
Chemical Vapor ◽  
Surface Shape ◽  
Root Mean Square Roughness ◽  
Multifractal Spectra ◽  
Self Assembled

The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, greatly influence such physical characteristics as the electricity, magnetic and optics nature to the thin films, etc. In this work, we use the fractal dimension and multifractal spectra to study the surface morphology of annealed InGaN/GaN self-assembled quantum dot (SAQD) films. Samples used in this study were grown on (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metalorganic chemical vapor deposition (MOCVD) reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealing conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces decreased after thermal annealing. It can be seen that a smoother surface was obtained after an annealing temperature of 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also include a mathematical model to describe the observation of fractal and multifractal characteristics in semiconductor nanostructure films.

Multifractal Spectra of INGaN/GaN Self-Assembled Quantum Dots Films

2010 ◽  
Vol 1 (3) ◽  
Author(s):  
Artde D. K. T. Lam
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
High Speed ◽  
Surface Characterization ◽  
Chemical Vapor ◽  
Surface Shape ◽  
Root Mean Square Roughness ◽  
Organic Chemical ◽  
Multifractal Spectra ◽  
Self Assembled

The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, have important influence to construct physical characteristics, such as electricity, magnetic, and optics nature to the thin films. In this work, we use the multifractal spectra to study the surface morphology of InGaN/GaN self-assembled quantum dot films after the annealed process. Samples used in this study were grown on the (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metal-organic chemical vapor deposition reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealed conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces are decreased after the thermal annealing process. It can be seen that a smoother surface was obtained under an annealing temperature at 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also described a mathematical modeling method for the observation of the fractal and multifractal characteristics in a semiconductor nanostructure films.

Texture and Nano Mechanical Properties of YSZ Electrolyte Thin Films Prepared by CCVD and PLD

2003 ◽  
Vol 778 ◽  
Author(s):  
Z. Xu ◽  
C. Waters ◽  
X. Wang ◽  
N. Sudhir ◽  
S. Yarmolenko ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Surface Roughness ◽  
Chemical Vapor ◽  
Film Deposition ◽  
Advanced Materials ◽  
State University ◽  
Composite Thin Films ◽  
Ysz Electrolyte ◽  
T State

AbstractComposite thin films of yttria stabilized zirconia (YSZ) and alumina (Al2O3) have been synthesized using liquid fuel combustion chemical vapor deposition (CCVD) and pulsed laser deposition (PLD) in the NSF Center for Advanced Materials and Smart Structures (CAMSS) at North Carolina A&T State University. With the CCVD technique, addition of alumina was realized by adding the designated amount of aluminum-organic in the reagent solution; while with PLD, doping of alumina in YSZ was accomplished by alternative ablations of an YSZ target and an alumina target. Variations in morphology, surface roughness and nano-mechanical properties of the composite thin films of Al2O3/YSZ were characterized. Crystal size of the films processed by CCVD was much larger than that processed by PLD; surface roughness follows the similar tendency. Upon high-temperature annealing, crystals in the PLD processed thin films grew up to 300 nm. The effect of Al2O3 in YSZ thin films on their nano-mechanical properties was dependent on the film deposition techniques in our research. For the films deposited by CCVD, addition of Al2O3 improved the nano hardness and elastic modulus of YSZ thin films, while a decline was observed in the mechanical properties of the films deposited by PLD.

Post-Annealing Effects on the Surface Roughness of Undoped and Al-Doped ZnO Thin Films Deposited by Atomic Layer Deposition

2013 ◽  
Vol 734-737 ◽  
pp. 2492-2495
Author(s):  
Yong June Choi ◽  
Kyung Mun Kang ◽  
Hyung Ho Park
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Atomic Layer Deposition ◽  
Morphological Changes ◽  
Atomic Layer ◽  
Root Mean Square Roughness ◽  
Post Annealing ◽  
Layer Deposition ◽  
Annealing Effects ◽  
Doped Zno

The post-annealing effects on the surface morphological changes of undoped and Al-doped ZnO (ZnO:Al) thin films deposited by atomic layer deposition (ALD) were investigated. The as-grown films were deposited by ALD at growth temperature of 200°C and also, post-annealing of the samples was accomplished at 300°C for 1 h under nitrogen atmosphere. The X-ray diffraction of the films was monitored to study the crystallinity of the films according to post-anneal. The field emission-scanning electron microscopy and atomic force microscopy were conducted to observe the surface morphological changes and measure the root-mean-square roughness of the films in order to analysis the post-annealing effects on the surface roughness of the films.

Low Dielectric Constant, High Temperature Stable Copolymer Thin Films by Room Temperature Chemical Vapor Deposition

1994 ◽  
Vol 343 ◽  
Author(s):  
Justin F. Gaynor ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
High Speed ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Low Dielectric Constant ◽  
Low Dielectric ◽  
Conformal Coatings

ABSTRACTPolyxylylene thin films grown by the chemical vapor deposition (CVD) process have long been utilized to achieve uniform, pinhole-free conformal coatings. They have recently been cited as possible low dielectric constant films for intermetal layers in high-speed ICs. Homopolymer films are highly crystalline and have a glass transition temperature around room temperature. We have demonstrated that room temperature copolymerization with previously untested comonomers can be achieved during the CVD process. Copolymerizing chloro-p-xylylene with perfluorooctyl methacrylate results in the dielectric constant at optical frequencies being lowered from 2.68 to 2.19. Copolymerizing p-xylylene with vinylbiphenyl resulted in films which increase the temperature at which oxidative scission occurs from 320 to 450C. Copolymerizing p-xylylene with 9-vinylanthracene resulted in a brittle, yellow film.

Antiphase boundaries in β-Sic thin films

1987 ◽  
Vol 45 ◽  
pp. 282-283
Author(s):  
K. L. More ◽  
J. Bentley ◽  
R. F. Davis
Keyword(s):  
Thin Films ◽  
High Speed ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Wide Bandgap ◽  
Silicon Substrates ◽  
State University ◽  
North Carolina State University ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Beta-SiC thin films are currently being grown via chemical vapor deposition (CVD) at North Carolina State University for potential use as a semiconductor material. Silicon carbide is a wide bandgap semiconductor with a high, saturated electron drift velocity and, as such, is a primary candidate material for high-temperature, high-speed, and high-frequency electronic devices. The β-SiC thin films are epitaxially grown on {100} silicon substrates by CVD of silicon and carbon from vapors of SiH4 and C2H4 entrained in H2 at a growth temperature of 1633 K. Since there is a lattice mismatch of -20% and a difference in thermal expansion coefficients of ∼10% between the silicon substrate and β-SiC, the silicon surface is reacted with C2H4 at 1583 K. for 150 s to form a converted β-SiC surface layer, approximately 5 nm thick, which helps prevent the formation of cracks during the growth of the thin films. The films are grown at a rate of ∼2 μm/h and are grown as thick as 40 μm.

Plasma Activated Chemical Vapor Deposition of Polythiophene Thin Films

1992 ◽  
Vol 247 ◽  
Author(s):  
J. D. Targove ◽  
P. D. Haaland ◽  
C. A. Kutsche
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Reactive Ion Etching ◽  
Chemical Vapor ◽  
Film Properties ◽  
Ion Etching ◽  
Plasma Technique ◽  
Argon Stream

ABSTRACTPolythiophene thin films have been deposited by a novel plasma technique which avoids the disadvantages of conventional plasma-based processes. In particular, the thiophene precursor is injected into an activated argon stream rather than into a plasma. The films produced are dense and uniform, with surface roughness of less than 1 nm. Other film properties are comparable to films deposited by more conventional methods. These films have been processed by reactive ion etching to produce micron-scale features.

scholarly journals Bifunctional TiO2/AlZr Thin Films on Steel Substrate Combining Corrosion Resistance and Photocatalytic Properties

Coatings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 564 ◽  
Author(s):  
Villardi de Oliveira ◽  
Alhussein ◽  
Creus ◽  
Schuster ◽  
Schlegel ◽  
...  
Keyword(s):  
Thin Films ◽  
Corrosion Resistance ◽  
High Speed ◽  
Sea Water ◽  
Steel Substrate ◽  
Film Surface ◽  
High Speed Steel ◽  
Chemical Vapor ◽  
Photocatalytic Properties ◽  
Tio2 Thin Films

A novel multi-functional bilayer coating combining an anti-corrosion Al–Zr (4 at.% Zr) underlayer and an anti-biofouling TiO2 top layer was deposited on high-speed steel (HSS) substrates. Al–Zr (4 at.% Zr) film, deposited by DC magnetron sputtering, which is a single phased supersaturated solid solution of Zr in Al, is used to provide sacrificial corrosion resistance of steels and TiO2 is added as a top layer to induce photocatalytic activity and hydrophilic behavior which can generate antifouling properties in order to slow down the biofouling process. The top TiO2 films, deposited at 550 °C by AACVD (aerosol-assisted chemical vapor deposition), consisting of anatase TiO2 microflowers physically attached to the TiO2 thin films present a high decomposition rate of Orange G dye (780 × 10−10 mol L−1·min−1). The enhanced photocatalytic performance is associated with the rough network and the presence of TiO2 microflowers capable of supporting the enhanced loading of organic contaminants onto the film surface. Electrochemical tests in saline solution have revealed that bilayer films provide cathodic protection for the steel substrate. The Al–Zr/TiO2 bilayer presents a lower corrosion current density of 4.01 × 10−7 A/cm2 and a corrosion potential of −0.61 V vs Ag/AgCl, offering good protection through the preferential oxidation of the bilayer and an increased pitting resistance. The proposed functionalized coating combining anticorrosion and photocatalytic properties is a promising candidate for an anti-fouling system in sea water.

DEVELOPMENT OF FRACTAL DIMENSION AND CHARACTERISTIC ROUGHNESS MODELS FOR TURNED SURFACE OF CARBON STEELS

Fractals ◽  
2016 ◽  
Vol 24 (04) ◽  
pp. 1650042 ◽  
Author(s):  
XUE ZUO ◽  
HUA ZHU ◽  
YUANKAI ZHOU ◽  
CONG DING ◽  
GUODONG SUN
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Feed Rate ◽  
High Speed ◽  
Carbon Steels ◽  
Response Surfaces ◽  
Spindle Speed ◽  
Surface Parameters ◽  
Dimension Formula ◽  
Material Hardness

Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness [Formula: see text]a, fractal dimension [Formula: see text] and characteristic roughness [Formula: see text] are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, [Formula: see text] and [Formula: see text] are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting [Formula: see text]a, while material hardness is the most dominant parameter affecting [Formula: see text]. Material hardness and spindle speed have the same influence on [Formula: see text]. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating [Formula: see text]a, [Formula: see text] and [Formula: see text]. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small [Formula: see text]a and large [Formula: see text] and [Formula: see text] can be obtained by selecting a high speed and a large hardness material. According to the established models, [Formula: see text]a, [Formula: see text] and [Formula: see text] of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.

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