Higher Order Nonlinear Dielectric Microscopy

2001 ◽  
Vol 688 ◽  
Author(s):  
Yasuo Cho ◽  
Koya Ohara
Keyword(s):  
Depth Resolution ◽  
Higher Order ◽  
Ferroelectric Materials ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Surface Layers ◽  
Nonlinear Dielectric ◽  
Microscopy Technique ◽  
Cell Thickness

AbstractA higher order nonlinear dielectric microscopy technique with higher lateral and depth resolution than conventional nonlinear dielectric imaging is investigated. The proposed technique involves the measurement of higher order nonlinear dielectric constants, with a depth resolution of down to 1.5 nm. The technique is demonstrated to be very useful for observing surface layers of the order of unit cell thickness on ferroelectric materials.

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

Carrier Redistribution Analysis of Gate-Biased SiC Power-MOSFET Using Super-Higher-Order Scanning Nonlinear Dielectric Microscopy

2015 ◽  
Author(s):  
Norimichi Chinone ◽  
Yasuo Cho
Keyword(s):  
Cross Section ◽  
Measurement System ◽  
Higher Order ◽  
Depletion Layer ◽  
Gate Bias ◽  
Power Mosfet ◽  
Nonlinear Dielectric ◽  
Voltage Dependent ◽  
Carrier Redistribution ◽  
Source Voltage

Abstract Gate-bias dependent depletion layer distribution and carrier distributions in cross-section of SiC power MOSFET were measured by newly developed measurement system based on super-higher-order scanning nonlinear dielectric microscope. The results visualized gate-source voltage dependent redistribution of depletion layer and carrier.

Two-Dimensional Local Deep-Level Transient Spectroscopy Imaging Using Super-Higher-Order Scanning Nonlinear Dielectric Microscopy

2016 ◽  
Author(s):  
N. Chinone ◽  
Y. Cho ◽  
R. Kosugi ◽  
Y. Tanaka ◽  
S. Harada ◽  
...  
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Higher Order ◽  
Trap Density ◽  
New Technique ◽  
Two Dimensional ◽  
Nonlinear Dielectric ◽  
Annealing Conditions ◽  
Transient Spectroscopy ◽  
A New Technique

Abstract A new technique for local deep level transient spectroscopy (DLTS) imaging using super-higher-order scanning nonlinear dielectric microscopy is proposed. Using this technique. SiCVSiC structure samples with different post oxidation annealing conditions were measured. We observed that the local DLTS signal decreases with post oxidation annealing (POA), which agrees with the well-known phenomena that POA reduces trap density. Furthermore, obtained local DLTS images had dark and bright areas, which is considered to show the trap distribution at/near SiCVSiC interface.

scholarly journals A hybrid broadband metalens operating at ultraviolet frequencies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Dielectric Material ◽  
Berry Phase ◽  
Uv Light ◽  
Fdtd Method ◽  
Numerical Aperture ◽  
Limited Range ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Phase Method ◽  
Frequency Range

AbstractThe investigation on metalenses have been rapidly developing, aiming to bring compact optical devices with superior properties to the market. Realizing miniature optics at the UV frequency range in particular has been challenging as the available transparent materials have limited range of dielectric constants. In this work we introduce a low absorption loss and low refractive index dielectric material magnesium oxide, MgO, as an ideal candidate for metalenses operating at UV frequencies. We theoretically investigate metalens designs capable of efficient focusing over a broad UV frequency range (200–400 nm). The presented metalenses are composed of sub-wavelength MgO nanoblocks, and characterized according to the geometric Pancharatnam–Berry phase method using FDTD method. The presented broadband metalenses can focus the incident UV light on tight focal spots (182 nm) with high numerical aperture ($$\hbox {NA}\approx 0.8$$ NA ≈ 0.8 ). The polarization conversion efficiency of the metalens unit cell and focusing efficiency of the total metalens are calculated to be as high as 94%, the best value reported in UV range so far. In addition, the metalens unit cell can be hybridized to enable lensing at multiple polarization states. The presented highly efficient MgO metalenses can play a vital role in the development of UV nanophotonic systems and could pave the way towards the world of miniaturization.

scholarly journals Dealumination of ZSM-5 — Characterization by TPD, DTA/DTG, XPS and Adsorption Measurements

1988 ◽  
Vol 5 (2) ◽  
pp. 127-138 ◽  
Author(s):  
E. Alsdorf ◽  
M. Feist ◽  
H. Fichtner-Schmittler ◽  
Th. Gross ◽  
H.-J. Jerschkewitz ◽  
...  
Keyword(s):  
Adsorbed Water ◽  
Unit Cell ◽  
Surface Layers ◽  
Temperature Range

A series of ZSM 5 samples obtained by dealumination is studied by TPD, DTA/DTG, XPS and adsorption measurements. The amount of adsorbed water at p/p0 ≦ 0.1 and the amount of chemisorbed NH3 corresponding to the TPD peak at 693–723 K correlate with the number of framework aluminium atoms per unit cell. At strong dealumination an enrichment of non-framework aluminium in the surface layers of the crystals was found. The HZSM-57 zeolites are transformed into silicalite-like samples during the course of the DTA experiment in the temperature range 973–1273 K.

scholarly journals Effective properties of a porous inhomogeneously polarized by direction piezoceramic material with full metalized pore boundaries: Finite element analysis

2020 ◽  
Vol 10 (05) ◽  
pp. 2050018
Author(s):  
Andrey Nasedkin ◽  
Mohamed Elsayed Nassar
Keyword(s):  
Finite Element ◽  
Effective Properties ◽  
Dielectric Material ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Polarization Field ◽  
Electrostatic Problem ◽  
Element Analysis ◽  
Piezoceramic Material ◽  
Homogenization Problems

This paper concerns the homogenization problems for porous piezocomposites with infinitely thin metalized pore surfaces. To determine the effective properties, we used the effective moduli method and the finite element approaches, realized in the ANSYS package. As a simple model of the representative volume, we applied a unit cell of porous piezoceramic material in the form of a cube with one spherical pore. We modeled metallization by introducing an additional layer of material with very large permittivity coefficients along the pore boundary. Then we simulated the nonuniform polarization field around the pore. For taking this effect into account, we previously solved the electrostatic problem for a porous dielectric material with the same geometric structure. From this problem, we obtained the polarization field in the porous piezomaterial; after that, we modified the material properties of the finite elements from dielectric to piezoelectric with element coordinate systems whose corresponding axes rotated along the polarization vectors. As a result, we obtained the porous unit cell of an inhomogeneously polarized piezoceramic matrix. From the solutions of these homogenization problems, we observed that the examined porous piezoceramics composite with metalized pore boundaries has more extensive effective transverse and shear piezomoduli, and effective dielectric constants compared to the conventional porous piezoceramics. The analysis also showed that the effect of the polarization field inhomogeneity is insignificant on the ordinary porous piezoceramics; however, it is more significant on the porous piezoceramics with metalized pore surfaces.

Ion Beam Modification of BiSrCaCuO Ultrathin Films of Nearly Three Half-Unit-Cell Thickness

1996 ◽  
Vol 35 (Part 2, No. 3B) ◽  
pp. L387-L390 ◽  
Author(s):  
Jonghun You ◽  
Masatsugu Kaise ◽  
Kazuo Saito
Keyword(s):  
Ultrathin Films ◽  
Ion Beam ◽  
Unit Cell ◽  
Ion Beam Modification ◽  
Cell Thickness
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