Investigations of polarization profiles in multilayer systems by using the laser intensity modulation method

Bloss, P.; Schäfer, Hartmut

doi:10.1063/1.1144889

Cited by 58 publications

(20 citation statements)

References 22 publications

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“…Details about the deconvolution scheme applicable to both TP and LIMM data may be found in previous LIMM papers. 26,27 We define the mean square of errors ͑MSE͒ of the fit as…”

Section: Details For the Deconvolution Of The Tp Responsesmentioning

confidence: 99%

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Electric-field profile and thermal properties in substrate-supported dielectric films

2000

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The transient pyroelectric response of a dielectric film on a substrate is used to determine both the electricfield profile across the film and its thermal properties. The response is a convolution of the field and temperature profile. A closed-form expression for the transient temperature profile is obtained for a generic model in terms of thermal parameters. This expression allows analysis of the pyroelectric response using an iterative procedure consisting of deconvolution and variation of thermal parameters. Tikhonov regularization is used in the deconvolution with a Honerkamp-Weese self-consistent regularization parameter. Simulations show that, at least in the cases tested, the electric-field profile, the thermal diffusivity and conductivity ͑and thus the heat capacity, which is their ratio͒, and the thermal resistance of the dielectric/substrate interface can be determined. Experiments on polyimide films adhered to substrates unambiguously reveal bound negative charge within a small depth of the free surface of virgin samples and also weaker, broader charge distributions injected from the substrate in samples under an applied voltage. The analysis resolves both sharp and broad features and gives thermal properties characteristic of the near-surface region, suggesting that the heat capacity may be significantly higher in this region than in the bulk.

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“…Details about the deconvolution scheme applicable to both TP and LIMM data may be found in previous LIMM papers. 26,27 We define the mean square of errors ͑MSE͒ of the fit as…”

Section: Details For the Deconvolution Of The Tp Responsesmentioning

confidence: 99%

“…Grid-point spacings were determined by a power law 26,27 with y 1 ϭ0 at the electrode/dielectric interface and y N ϭ1 at the dielectric/substrate interface. The first grid point inside the dielectric was at y 2 ϭb(␦ min /L), where bϭ0.33, .…”

Section: Details For the Deconvolution Of The Tp Responsesmentioning

confidence: 99%

Electric-field profile and thermal properties in substrate-supported dielectric films

2000

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“…The principle of the LIMM measurements [14,16,17] not switchable, and even in elastomers with low crossis as follows. The sample is placed between non-transpar ent linking densities, the long switching times do not allow metal electrodes that are vacuum deposited on a 2.5 mm determination of P s from these measurements [12].…”

Section: Samplementioning

confidence: 99%

Measurement of the pyroelectric response and of the thermal diffusivity of microtomized sections of 'single crystalline' ferroelectric liquid crystalline elastomers

Leister¹,

Lehmann²,

Weber³

et al. 2000

Liquid Crystals

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The pyroelectric response and the thermal properties of microtomized sections of 'singlecrystalline' ferroelectric liquid crystalline elastomers (FLCE) have been investigated. The microtomized sections were manufactured in the thickness range from 20 to 100 mm. The roughness of the surfaces due to the cutting process was investigated with an alpha-stepper and found to be in the range of about 5 mm. The thermal di usivity of the elastomer at di erent temperatures was determined by placing the sample on a pyroelectric substrate and measuring the pyroelectric signal of the substrate under appropriate conditions. From the pyroelectric current spectra, information about the spatial distribution of the polarization could be deduced. It was found to be constant except in a range also about 5 mm near the surface. From the combination of this result and that of the alpha-stepper measurements, the conclusion is drawn that the molecular orientation at the surface is destroyed due to the cutting process. The magnitude of the spontaneous polarization was calculated from the pyroelectric measurements at di erent temperatures, making use of the thermal di usivity values.

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“…All the details of the mask are very well reproduced by the space-charge pattern. For the maximum signal-to-noise ratio, the samples had to be glued to a substrate in order to avoid thermo-elastic resonances [31].…”

Section: Space-charge Electretsmentioning

confidence: 99%

Thermal-Pulse Tomography of Space-charge and Polarization Distributions in Electret Polymers

et al. 2008

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A new, non-destructive technique for the analysis of electret materials is presented. Thermal-pulse tomography produces three-dimensional images of spacecharge and polarization distributions with a lateral resolution of better than 50 µm and a depth resolution of less than 0.5 µm. A focused-pulsed laser heats a circular spot on the opaque upper electrode. While diffusing through the sample, the thermal pulse causes local changes in the sample geometry or dielectric properties, resulting in a short-circuit current in the presence of space charge or electric dipoles. From the transient current, the distribution of the internal electric field can be reconstructed by means of scale transformation or regularization methods.

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Investigations of polarization profiles in multilayer systems by using the laser intensity modulation method

Cited by 58 publications

References 22 publications

Electric-field profile and thermal properties in substrate-supported dielectric films

Electric-field profile and thermal properties in substrate-supported dielectric films

Measurement of the pyroelectric response and of the thermal diffusivity of microtomized sections of 'single crystalline' ferroelectric liquid crystalline elastomers

Thermal-Pulse Tomography of Space-charge and Polarization Distributions in Electret Polymers

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