scholarly journals Combined Modeling of the Optical Anisotropy of Porous Thin Films

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 517 ◽  
Author(s):  
F. V. Grigoriev ◽  
V. B. Sulimov ◽  
A.V. Tikhonravov
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Anisotropy ◽  
Effective Medium Theory ◽  
Deposition Process ◽  
Dynamics Simulation ◽  
Porous Thin Films ◽  
Simulation Results ◽  
The Difference ◽  
Main Components

In this article, a combined approach for studying the optical anisotropy of porous thin films obtained by the glancing angle deposition is presented. This approach combines modeling on the atomistic and continuum levels. First, thin films clusters are obtained using the full-atomistic molecular dynamics simulation of the deposition process. Then, these clusters are represented as a medium with anisotropic pores, the shapes parameters of which are determined using the Monte Carlo based method. The difference in the main components of the refractive index is calculated in the framework of the anisotropic Bruggeman effective medium theory. The presented approach is tested and validated by comparing the analytical and simulation results for the model problems, and then is applied to silicon dioxide thin films. It is found that the maximum difference between the main components of the refractive index is 0.035 in a film deposited at an angle of 80°. The simulation results agree with the experimental data reported in the literature.

The Study on Young's Modulus of Multilayered Cu/Ni Multilayered Nano Thin Films by Molecular Dynamics Simulation

2014 ◽  
Vol 513-517 ◽  
pp. 113-116
Author(s):  
Jen Ching Huang ◽  
Fu Jen Cheng ◽  
Chun Song Yang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Strain Rate ◽  
Young’S Modulus ◽  
Potential Function ◽  
Dynamics Simulation ◽  
System Temperature ◽  
Simulation Results

The Youngs modulus of multilayered nanothin films is an important property. This paper focused to investigate the Youngs Modulus of Multilayered Ni/Cu Multilayered nanoThin Films under different condition by Molecular Dynamics Simulation. The NVT ensemble and COMPASS potential function were employed in the simulation. The multilayered nanothin film contained the Ni and Cu thin films in sequence. From simulation results, it is found that the Youngs modulus of Cu/Ni multilayered nanothin film is different at different lattice orientations, temperatures and strain rate. After experiments, it can be found that the Youngs modulus of multilayered nanothin film in the plane (100) is highest. As thickness of the thin film and system temperature rises, Youngs modulus of multilayered nanothin film is reduced instead. And, the strain rate increases, the Youngs modulus of Cu/Ni multilayered nanothin film will also increase.

scholarly journals Deposition Time induced Structural and Optical Properties of Lead Tin Sulphide Thin Films

2021 ◽  
pp. 455-458
Author(s):  
J. Damisa ◽  
J. O. Emegha ◽  
I. L. Ikhioya
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Tin Oxide ◽  
Deposition Time ◽  
Deposition Process ◽  
Structural And Optical Properties ◽  
X Ray ◽  
Prepared Material

Lead tin sulphide (Pb-Sn-S) thin films (TFs) were deposited on fluorine-doped tin oxide (FTO) substrates via the electrochemical deposition process using lead (II) nitrate [Pb(NO3)2], tin (II) chloride dehydrate [SnCl2.2H2O] and thiacetamide [C2H5NS] precursors as sources of lead (Pb), tin (Sn) and sulphur (S). The solution of all the compounds was harmonized with a stirrer (magnetic) at 300k. In this study, we reported on the improvements in the properties (structural and optical) of Pb-Sn-S TFs by varying the deposition time. We observed from X-ray diffractometer (XRD) that the prepared material is polycrystalline in nature. UV-Vis measurements were done for the optical characterizations and the band gap values were seen to be increasing from 1.52 to 1.54 eV with deposition time. In addition to this, the absorption coefficient and refractive index were also estimated and discussed.

scholarly journals Compositionally-Driven Formation Mechanism of Hierarchical Morphologies in Co-Deposited Immiscible Alloy Thin Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2635
Author(s):  
Max Powers ◽  
James A. Stewart ◽  
Rémi Dingreville ◽  
Benjamin K. Derby ◽  
Amit Misra
Keyword(s):  
Thin Films ◽  
Formation Mechanism ◽  
Threshold Value ◽  
Deposition Process ◽  
Immiscible Alloy ◽  
Multiple Length Scales ◽  
Constituent Element ◽  
The Difference ◽  
Microscopy Characterization

Co-deposited, immiscible alloy systems form hierarchical microstructures under specific deposition conditions that accentuate the difference in constituent element mobility. The mechanism leading to the formation of these unique hierarchical morphologies during the deposition process is difficult to identify, since the characterization of these microstructures is typically carried out post-deposition. We employ phase-field modeling to study the evolution of microstructures during deposition combined with microscopy characterization of experimentally deposited thin films to reveal the origin of the formation mechanism of hierarchical morphologies in co-deposited, immiscible alloy thin films. Our results trace this back to the significant influence of a local compositional driving force that occurs near the surface of the growing thin film. We show that local variations in the concentration of the vapor phase near the surface, resulting in nuclei (i.e., a cluster of atoms) on the film’s surface with an inhomogeneous composition, can trigger the simultaneous evolution of multiple concentration modulations across multiple length scales, leading to hierarchical morphologies. We show that locally, the concentration must be above a certain threshold value in order to generate distinct hierarchical morphologies in a single domain.

The Simulation Research of Nano-Indentation Based on the Molecular Dynamics

2012 ◽  
Vol 500 ◽  
pp. 702-706
Author(s):  
Ying Zhu ◽  
Ling Ling Xie ◽  
Sen Song ◽  
Shun Hen Qi ◽  
Qian Qian Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Large Scale ◽  
Optimization Method ◽  
Dynamics Simulation ◽  
Simulation Research ◽  
Nano Indentation ◽  
Simulation Calculation ◽  
Simulation Results ◽  
The Difference

The work in the optimization of the simulation of nanoindentation based on the molecular dynamics was mainly introduced in this paper. One optimization method, freeze atoms method was proposed according to the characteristics of nanoindentation process itself, then did the simulation calculation through the use of freeze atoms method and the traditional calculation method, It was found that the difference between simulation results and experimental results of hardness decreased gradually with enlarge the scale of molecular dynamics simulation (with increase of the indentation depth), from 32.39% of 5nm decreased to 14.6% of 25nm. By comparison, it was found that the optimized algorithm could improve the efficiency of simulation in large-scale molecular dynamics simulation., confirmed the correctness and effectiveness of freeze atoms method.

DEVELOPMENT OF A FORCE FIELD FOR ARTEMISININ AND MOLECULAR DYNAMICS SIMULATION OF THE DISSOLUTION OF ARTEMISININ IN DIFFERENT SOLVENTS

2013 ◽  
Vol 12 (05) ◽  
pp. 1350038 ◽  
Author(s):  
QUAN YANG ◽  
LUKE E. ACHENIE
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Force Field ◽  
Ethyl Acetate ◽  
Dynamics Simulation ◽  
Chemical Calculation ◽  
Dissolution Property ◽  
Simulation Results ◽  
The Difference ◽  
Acetate Aqueous Solution

Artemisinin is widely employed to treat malaria. A variety of experiments have been done to research the dissolution property of artemisinin in different solvents. To have an in-depth understanding of the property, it is essential to explore the dissolution property from molecular level with molecular dynamics (MD) simulation, which needs a satisfactory force field of artemisinin. Therefore in the research a quantum chemistry based force field was developed. The quantum chemical calculation at different levels was done and Hartree–Fock (HF) level calculation gives satisfactory results. The charge distribution was then determined successfully. The van der Waals (VDW) parameters of the C unit with sp3-C were tuned according to the difference between the dissolution enthalpy of artemisinin in ethanol and ethyl acetate. With the developed force field, MD method was employed to successfully simulate the dissolution property of artemisinin in different solvents. The simulation results show that artemisinin molecules tends to aggregate in water, while in the aqueous solution of ethanol, the same number of artemisinin molecules tends to disperse. Furthermore, simulation results show that 8 M ethyl acetate aqueous solution has better dissolution ability than 8 M ethanol aqueous. The simulation gave agreements with the experimental results.

scholarly journals Internal Stress Prediction and Measurement of Mid-Infrared Multilayer Thin Films

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1101
Author(s):  
Chuen-Lin Tien ◽  
Kuan-Po Chen ◽  
Hong-Yi Lin
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Internal Stress ◽  
Multilayer Thin Films ◽  
Infrared Band ◽  
Mid Infrared ◽  
Measured Stress ◽  
Band Pass ◽  
The Difference ◽  
Interfacial Force

We present an experimental method for evaluating interfacial force per width and predicting internal stress in mid-infrared band-pass filters (MIR-BPF). The interfacial force per width between the two kinds of thin-film materials was obtained by experimental measurement values, and the residual stress of the multilayer thin films was predicted by the modified Ennos formula. A dual electron beam evaporation system combined with ion-assisted deposition was used to fabricate mid-infrared band-pass filters. The interfacial forces per width for Ge/SiO2 and SiO2/Ge were 124.9 N/m and 127.6 N/m, respectively. The difference between the measured stress and predicted stress in the 23-layer MIR-BPF was below 0.059 GPa. The residual stresses of the four-layer film, as well as the 20-layer and 23-layer mid-infrared band-pass filter, were predicted by adding the interface stress to the modified Ennos formula. In the four-layer film, the difference between the predicted value and the measured stress of the HL (high–low refractive index) and LH (low–high refractive index) stacks were −0.384 GPa for (HL)2 and −0.436 GPa for (LH)2, respectively. The predicted stress and the measured stress of the 20-layer mid-infrared filter were −0.316 GPa and −0.250 GPa. The predicted stress and the measured stress of the 23-layer mid-infrared filter were −0.257 GPa and −0.198 GPa, respectively.

scholarly journals The Modification of Optical Properties of the Surfaces by the Glancing Angle Deposition Technique

2021 ◽  
Vol 16 (1) ◽  
pp. 91-100
Author(s):  
Ivan A. Azarov ◽  
Konstantin E. Kuper ◽  
Aleksey G. Lemzyakov ◽  
Vyacheslav V. Porosev ◽  
Alexander A. Shklyaev
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Titanium Dioxide ◽  
Optical Properties ◽  
Polycrystalline Material ◽  
Deposition Process ◽  
Glancing Angle Deposition ◽  
Glancing Angle ◽  
Lower Refractive Index ◽  
Angle Deposition

The paper considers the optical properties and structure of thin films of titanium dioxide formed by the glancing angle deposition method. It was show that this method allows the formation of coatings having a significantly lower refractive index than that of the initial material. Thus, the experimentally obtained value of the refractive index of thin films of titanium dioxide was ~1.2, which is almost two times less than that of a polycrystalline material. This allows you to use this method to produce the coatings with a variable refractive index using only one material, changing the geometry of the deposition process only.

Investigation of ultra-thin films of YBa2Cu3O7−δ grown on MgO

1990 ◽  
Vol 48 (4) ◽  
pp. 6-7
Author(s):  
S.K. Streiffer ◽  
C.B. Eom ◽  
J.C. Bravman ◽  
T.H. Geballet
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Deposition Process ◽  
Nucleation And Growth ◽  
Multilayer Structures ◽  
Rf Power ◽  
Oxygen Loss ◽  
Transmission Electron ◽  
Single Target ◽  
Mtorr Argon

The study of very thin (<15 nm) YBa2Cu3O7−δ (YBCO) films is necessary both for investigating the nucleation and growth of films of this material and for achieving a better understanding of multilayer structures incorporating such thin YBCO regions. We have used transmission electron microscopy to examine ultra-thin films grown on MgO substrates by single-target, off-axis magnetron sputtering; details of the deposition process have been reported elsewhere. Briefly, polished MgO substrates were attached to a block placed at 90° to the sputtering target and heated to 650 °C. The sputtering was performed in 10 mtorr oxygen and 40 mtorr argon with an rf power of 125 watts. After deposition, the chamber was vented to 500 torr oxygen and allowed to cool to room temperature. Because of YBCO’s susceptibility to environmental degradation and oxygen loss, the technique of Xi, et al. was followed and a protective overlayer of amorphous YBCO was deposited on the just-grown films.

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

1989 ◽  
Vol 47 ◽  
pp. 592-593
Author(s):  
J.B. Posthill ◽  
R.P. Burns ◽  
R.A. Rudder ◽  
Y.H. Lee ◽  
R.J. Markunas ◽  
...  
Keyword(s):  
Thin Films ◽  
Wide Band ◽  
Deposition Process ◽  
Heteroepitaxial Growth ◽  
Electron Microscopic ◽  
Wide Band Gap ◽  
Lattice Matching ◽  
Different Types ◽  
Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Effects of dopant concentration on the microstructure of tin- doped indium oxide thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 716-717
Author(s):  
I. A. Rauf
Keyword(s):  
Thin Films ◽  
Indium Oxide ◽  
Ionic Radius ◽  
Free Carrier ◽  
Electron Gun ◽  
Periodic Lattice ◽  
Oxide Thin Films ◽  
Transmission Electron ◽  
The Difference ◽  
Dopant Atoms

To understand the electronic conduction mechanism in Sn-doped indium oxide thin films, it is important to study the effect of dopant atoms on the neighbouring indium oxide lattice. Ideally Sn is a substitutional dopant at random indium sites. The difference in valence (Sn4+ replaces In3+) requires that an extra electron is donated to the lattice and thus contributes to the free carrier density. But since Sn is an adjacent member of the same row in the periodic table, the difference in the ionic radius (In3+: 0.218 nm; Sn4+: 0.205 nm) will introduce a strain in the indium oxide lattice. Free carrier electron waves will no longer see a perfect periodic lattice and will be scattered, resulting in the reduction of free carrier mobility, which will lower the electrical conductivity (an undesirable effect in most applications).One of the main objectives of the present investigation is to understand the effects of the strain (produced by difference in the ionic radius) on the microstructure of the indium oxide lattice when the doping level is increased to give high carrier densities. Sn-doped indium oxide thin films were prepared with four different concentrations: 9, 10, 11 and 12 mol. % of SnO2 in the starting material. All the samples were prepared at an oxygen partial pressure of 0.067 Pa and a substrate temperature of 250°C using an Edwards 306 coating unit with an electron gun attachment for heating the crucible. These deposition conditions have been found to give optimum electrical properties in Sn-doped indium oxide films. A JEOL 2000EX transmission electron microscope was used to investigate the specimen microstructure.

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