scholarly journals Simulation of the photonic nanojet effect for Raman scattering enhancement in the diagnostics of oxide films

2021 ◽  
Vol 2086 (1) ◽  
pp. 012146
Author(s):  
A I Ivanina ◽  
D S Agafonova ◽  
N V Roshina ◽  
I A Lamkin
Keyword(s):  
Refractive Index ◽  
Raman Scattering ◽  
Perovskite Phase ◽  
Oxide Films ◽  
Pyrochlore Phase ◽  
Substrate Material ◽  
Spherical Particles ◽  
Optimal Interval ◽  
Photonic Nanojet ◽  
Film Substrate

Abstract In this paper, by means of numerical simulations in the COMSOL Multiphysics software it’s demonstrated that Raman scattering enhancement can be achieved for the diagnosis of metal oxide films using spherical particles made of barium titanate with a 10-micron diameter sphere. The formation of photonic nanojet in the sphere/film/substrate system at different radiation wavelengths and microsphere refractive index, film, and substrate was studied. The optimal interval of the particle refractive index is n≈1.8-2 was determined, at which the gain occurs directly at the particle/film interface. It is shown that for the UV wavelength range of wavelengths and film thicknesses from 50 to 200 nm, the gain is maximum. For ZnO and PZT films in the perovskite phase, sitall and quartz are preferred as the substrate material, while for PZT in the pyrochlore phase, sapphire is preferred.

Crystallization of Amorphous Thin BST/MgO(001) Films Grown by R.F. Magnetron Sputtering

1997 ◽  
Vol 493 ◽  
Author(s):  
D. Y. Noh ◽  
H. H. Lee ◽  
J. H. Je ◽  
H. K. Kim
Keyword(s):  
Thick Film ◽  
Intermediate Phase ◽  
Perovskite Phase ◽  
Pyrochlore Phase ◽  
Interface Area ◽  
Crystalline Orientation ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Experiment ◽  
Film Substrate

ABSTRACTThe crystallization of amorphous BST thin films was studied in a synchrotron x-ray scattering experiment. At around 600°C, an intermediate phase, which was suspected to be a metastable pyrochlore phase, was formed. The x-ray reflectivity curves showed that the film-substrate interface became rough as the pyrochlore-like phase was formed. This suggests that the pyrochlore phase was nucleated near the interface area. Upon further annealing to higher temperatures, the film transformed to the crystalline perovskite phase. The crystallization was sensitive to the film thickness. In the thin 550Å thick film, the crystallization occurred at 750 °C with the <001> preferred orientation. On the other hand, the 5500Å thick film became crystalline even at 500°C with random crystalline orientation. The observed thickness dependence of the crystallization suggests that the crystalline perovskite phase was nucleated in the bulk of the film, rather than the near interface area.

scholarly journals Preparation features and electrical properties of Na0.5Bi0.5TiO3 thin films

2020 ◽  
Vol 28 (1) ◽  
pp. 33-38
Author(s):  
T. V. Kruzina ◽  
S. A. Popov ◽  
Yu. N. Potapovich ◽  
S. I. Ryabtsev ◽  
A. S. Rutskiy
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Electric Field ◽  
Perovskite Phase ◽  
Pyrochlore Phase ◽  
Ex Situ ◽  
Structural Defects ◽  
Leakage Currents ◽  
Si Substrates ◽  
Film Substrate

Some special features of Na0.5Bi0.5TiO3 (NBT) thin films preparation process and electrical properties of the films are presented. The NBT films were grown on both Pt/sitall and Pt/TiO2/SiO2/Si substrates by ex-situ method with high-frequency (13.56 MHz) magnetron deposition. Thermal treatment of the films was carried out in the temperature range 550°С – 700°С in air. Obtained X-ray diffraction data show that annealing at 700°C promotes crystallization of NBT films in ferroelectric perovskite phase with minor inclusions of pyrochlore phase. Dielectric hysteresis (P-E) loops in electric field of 90 kV/cm (50 Hz) and the current density-electric field (J-E) characteristics of the films are investigated. It is found that densities of leakage currents in weak fields depend on the film substrate and are significantly lower for the films deposited on the Pt/sitall structure (~6.9 10-10 A/cm2) in comparison with the films deposited on the Pt/TiO2/SiO2/Si structure (~10-6 A/cm2). The main mechanisms of leakage currents in thin NBT ferroelectric films and the role of structural defects in charge transfer process are discussed.

Effect of substrate on phase formation and surface morphology of sol-gel lead-free KNbO3, NaNbO3, and K0.5Na0.5NbO3 thin films

2012 ◽  
Vol 66 (8) ◽  
Author(s):  
Helena Bruncková ◽  
Ľubomír Medvecký ◽  
Pavol Hvizdoš
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Lead Free ◽  
Spherical Particles ◽  
Si Substrate ◽  
Electron Microscopic ◽  
Homogeneous Microstructure

AbstractEnvironmentally acceptable lead-free ferroelectric KNbO3 (KN) or NaNbO3 (NN) and K0.5Na0.5NbO3 (KNN) thin films were prepared using a modified sol-gel method by mixing potassium acetate or sodium acetate or both with the Nb-tartrate complex, deposited on the Pt/Al2O3 and Pt/SiO2/Si substrates by a spin-coating method and sintered at 650°C. X-ray diffraction (XRD) analysis indicated that the NN and KNN films on the Pt/SiO2/Si substrate possessed a single perovskite phase, while NN and KNN films on the Pt/Al2O3 substrate contained a small amount of secondary pyrochlore phase, as did KN films on both substrates. Scanning electron microscopic (SEM) and atomic force microscopic (AFM) analyses confirmed that roughness R q of the thin KNN/Pt/SiO2/Si film (≈ 7.4 nm) was significantly lower than that of the KNN/Pt/Al2O3 film (≈ 15 nm). The heterogeneous microstructure composed of small spherical and larger needle-like or cuboidal particles were observed in the KN and NN films on both substrates. The homogeneous microstructure of the KNN thin film on the Pt/SiO2/Si substrate was smoother and contained finer spherical particles (≈ 50 nm) than on Pt/Al2O3 substrates (≈ 100 nm). The effect of different substrates on the surface morphology of thin films was confirmed.

scholarly journals Raman scattering in high-refractive-index nanostructures

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Søren Raza ◽  
Anders Kristensen
Keyword(s):  
Raman Spectroscopy ◽  
Refractive Index ◽  
Raman Scattering ◽  
Bound States ◽  
Stimulated Raman Scattering ◽  
Dielectric Materials ◽  
High Refractive Index ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Enhancement ◽  
The Impact

AbstractThe advent of resonant dielectric nanomaterials has provided a new path for concentrating and manipulating light on the nanoscale. Such high-refractive-index materials support a diverse set of low-loss optical resonances, including Mie resonances, anapole states, and bound states in the continuum. Through these resonances, high-refractive-index materials can be used to engineer the optical near field, both inside and outside the nanostructures, which opens up new opportunities for Raman spectroscopy. In this review, we discuss the impact of high-refractive-index nano-optics on Raman spectroscopy. In particular, we consider the intrinsic Raman enhancement produced by different dielectric resonances and their theoretical description. Using the optical reciprocity theorem, we derive an expression which links the Raman enhancement to the enhancement of the stored electric energy. We also address recent results on surface-enhanced Raman spectroscopy based on high-refractive-index dielectric materials along with applications in stimulated Raman scattering and nanothermometry. Finally, we discuss the potential of Raman spectroscopy as a tool for detecting the optical near-fields produced by dielectric resonances, complementing reflection and transmission measurements.

Stabilization of perovskite phase and dielectric properties of Pb(Zn, Mg)1/3Nb2/3O3-PbTiO3 ceramics prepared by excess constituent oxides

1994 ◽  
Vol 9 (10) ◽  
pp. 2634-2644 ◽  
Author(s):  
Hyun M. Jang ◽  
Kyu-Mann Lee ◽  
Moon-Ho Lee
Keyword(s):  
Phase Transition ◽  
Diffuse Phase Transition ◽  
Short Range ◽  
Perovskite Phase ◽  
Complex Impedance ◽  
Pyrochlore Phase ◽  
Charge Carriers ◽  
Pbtio3 Ceramics ◽  
Additional Formation ◽  
Diffuse Phase

The perovskite phase in PZN-PMN-PT (PbZn1/3Nb2/3O3-PbMg1/3Nb2/3O3-PbTiO3) pseudoternary ceramics was stabilized by the addition of excess constituent divalent oxides (PbO, MgO, and ZnO). 5 mol% excess MgO or 7.5 mol% excess PbO was sufficient to eliminate the remnant cubic pyrochlore phase after sintering at 1100 °C for 1 h. The enhanced diffuse phase transition (DPT) and the decrease in the electrical resistivity were observed in the presence of excess ZnO or MgO. These were interpreted in terms of the additional formation of negatively charged, short-range ordered 1: 1 domains with a concomitant generation of charge carriers (holes). The behavior of excess MgO or ZnO at concentrations above 5 mol% was studied by examining complex impedance patterns.

Thickness-Dependent Interface Parameters of Silicon Oxide Films Grown on Plasma Hydrogenated Silicon

2010 ◽  
Vol 159 ◽  
pp. 163-166 ◽  
Author(s):  
S. Alexandrova ◽  
A. Szekeres
Keyword(s):  
Refractive Index ◽  
Plasma Treatment ◽  
Silicon Oxide ◽  
Oxide Films ◽  
Oxide Thickness ◽  
Hydrogenated Silicon ◽  
Oxide Structure ◽  
Interface Parameters

In the present paper we discuss the defects at the oxide/Si interface and the structure of silicon oxide films grown on plasma hydrogenated (100) and (111)Si. The effect of oxide thickness ranging from 7 to 40 nm on the interface parameters was examined. Electrically active defects were characterized through C-V and G-V measurements. The dependence of the refractive index on oxide thickness was studied. Information on the oxide structure was inferred through the refractive index evaluated from ellipsometric measurements. From both, the electrical and optical results a characteristic oxide thickness was found, below which the oxide structure is different from SiO2, most probably SiOх. It is related to a modified Si surface during the pre-oxidation plasma treatment and its value depends on Si orientation and pre-clean conditions. A characteristic oxide thickness of 13 nm was found for Si hydrogenated without heating and, of 9 nm for Si hydrogenated at 300oC.

scholarly journals Switchable Photonic Nanojet by Electro-Switching Nematic Liquid Crystals

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 72 ◽  
Author(s):  
Bintao Du ◽  
Jun Xia ◽  
Jun Wu ◽  
Jian Zhao ◽  
Hao Zhang
Keyword(s):  
Refractive Index ◽  
Liquid Crystals ◽  
Double Layer ◽  
Nematic Liquid Crystals ◽  
Surrounding Medium ◽  
Refractive Index Change ◽  
Electric Energy ◽  
Incident Wavelength ◽  
Photonic Nanojet ◽  
Energy Focusing

This paper first presents a switchable photonic nanojet (PNJ) generated by a polystyrene (PS) microsphere immersed in nematic liquid crystals (NLCs). The PNJ is switched by applying external voltage, which originates from the refractive index change in the surrounding medium caused by the field-induced realignment of liquid crystal molecules. By tuning the refractive index of NLCs larger or smaller than that of the PS microsphere, the PNJ can be switched off or on. Moreover, we present an optimization study to seek a better electric energy focusing property of the PNJ. Our results reveal that the switchability of PNJ can be optimized by applying a shorter incident wavelength, a double-layer microsphere, and a PS ellipsoid. The full width at half-maximum (FWHM) generated by the PS ellipsoid is narrower than that generated by the microsphere with a shorter incident wavelength. The intensity contrast of the PS ellipsoid is higher than that of the double-layer microsphere. As a whole, the switchability of PNJ can be best optimized by a PS ellipsoid. This should open the way for the development of integrated photonic devices.

Barium titanate-added lead nickel niobate ferroelectrics: Accelerated perovskite formation and dielectric properties

1996 ◽  
Vol 11 (12) ◽  
pp. 3064-3070 ◽  
Author(s):  
Chung-Hsin Lu ◽  
Jai-Fang Wu
Keyword(s):  
Frequency Dependence ◽  
Solid Solutions ◽  
Perovskite Phase ◽  
Pyrochlore Phase ◽  
Lattice Parameter ◽  
Cubic Symmetry ◽  
Dielectric Peak ◽  
Random Arrangement ◽  
Reaction Conversion ◽  
Lead Nickel

The addition of BaTiO3 to Pb(Ni1/3Nb2/3)O3 has been confirmed to vary the formation kinetics of the perovskite solid solutions of Pb(Ni1/3Nb2/3)O3-BaTiO3, and to suppress the generation of the pyrochlore phase. A semiquantitatively calculated reaction conversion verified that increasing the BaTiO3 content significantly accelerated the formation of the perovskite solid solutions. The formed solid solutions of Pb(Ni1/3Nb2/3)O3-BaTiO3 (up to 90 mol% of BaTiO3) exhibited a cubic symmetry at room temperature. The lattice parameter monotonously decreased with an increase in the BaTiO3 content. The structural stability of the perovskite phase was found to be enhanced by the addition of BaTiO3 as well. The formed solid solutions were able to maintain the perovskite structure without decomposition when heated up to 1250 °C. The frequency dependence of the apparent Curie temperature and the diffuseness of the dielectric peak of sintered specimens were increased with increasing the BaTiO3 content up to 50 mol%. Whereas with further addition, the relaxor characteristics in the specimens became obscure, associated with lower frequency dependence and less broadening of the dielectric maximum. The largest broadening of the dielectric peak occurred at x = 0.5, implying that this composition exhibited the most disordered structure, which is probably related to the most random arrangement of B-site cations in oxygen octahedran.

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