Cross-plane Thermoreflectance Imaging of Thermoelectric Elements

2005 ◽  
Vol 886 ◽  
Author(s):  
Peter M. Mayer ◽  
Rajeev J. Ram
Keyword(s):  
Temperature Distribution ◽  
Spatial Resolution ◽  
Quasi Equilibrium ◽  
Thermal Impedance ◽  
Thermal Measurements ◽  
Systems Identification ◽  
Lock In ◽  
Operational Device

ABSTRACTThis paper presents the first cross-plane thermoreflectance image of the temperature distribution in a thermoelectric (TE) element under bias. Using the technique of lock-in CCD thermoreflectance imaging, we can map the temperature distribution of an operational device with submicron spatial resolution and a temperature resolution of 10 mK. As such it offers a complete picture of the quasi-equilibrium transport within the device. The submicron resolution of the thermoreflectance image enables clear determination of localized heating due at interfaces - for example to due contact resistance - and thermal impedance mismatch within samples. The high spatial resolution is ideal for the characterization of thin-film thermoelectric materials where data from conventional techniques (such as the transient Harman method) are difficult to interpret. This paper also presents the first thermoreflectance data we are aware of for BiTe-based material systems. Identification and separation of the Peltier and Joule components of the heating are possible, and finite difference simulations of the devices are presented for comparison with experiment. In this way it is possible to simultaneously acquire information about the Seebeck coefficient, electrical conductivity, and thermal conductivity of the thermoelectric material. The measurements demonstrate the feasibility of non-contact thermal measurements at the sub-micron scale.

Characterization and Control of Copper CMP with Optoacoustic Metrology

2001 ◽  
Vol 671 ◽  
Author(s):  
Michael Gostein ◽  
Paul Lefevre ◽  
Alex A. Maznev ◽  
Michael Joffe
Keyword(s):  
Film Thickness ◽  
Spatial Resolution ◽  
Chemical Mechanical Polishing ◽  
High Spatial Resolution ◽  
Mechanical Polishing ◽  
Length Measurement ◽  
And Control ◽  
Non Destructive

ABSTRACTWe discuss applications of optoacoustic film thickness metrology for characterization of copper chemical-mechanical polishing (CMP). We highlight areas where the use of optoacoustics for CMP characterization provides data complementary to that obtained by other techniques because of its ability to directly measure film thickness with high spatial resolution in a rapid, non-destructive manner. Examples considered include determination of planarization length, measurement of film thickness at intermediate stages of polish, and measurement of arrays of metal lines.

scholarly journals Characterization of Self-Heating Process in GaN-Based HEMTs

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1305 ◽  
Author(s):  
Daniel Gryglewski ◽  
Wojciech Wojtasiak ◽  
Eliana Kamińska ◽  
Anna Piotrowska
Keyword(s):  
Communication Systems ◽  
Accurate Determination ◽  
Heating Process ◽  
Equivalent Circuits ◽  
High Electron ◽  
Thermal Impedance ◽  
Self Heating ◽  
Gan Hemt

Thermal characterization of modern microwave power transistors such as high electron-mobility transistors based on gallium nitride (GaN-based HEMTs) is a critical challenge for the development of high-performance new generation wireless communication systems (LTE-A, 5G) and advanced radars (active electronically scanned array (AESA)). This is especially true for systems operating with variable-envelope signals where accurate determination of self-heating effects resulting from strong- and fast-changing power dissipated inside transistor is crucial. In this work, we have developed an advanced measurement system based on DeltaVGS method with implemented software enabling accurate determination of device channel temperature and thermal resistance. The methodology accounts for MIL-STD-750-3 standard but takes into account appropriate specific bias and timing conditions. Three types of GaN-based HEMTs were taken into consideration, namely commercially available GaN-on-SiC (CGH27015F and TGF2023-2-01) and GaN-on-Si (NPT2022) devices, as well as model GaN-on-GaN HEMT (T8). Their characteristics of thermal impedance, thermal time constants and thermal equivalent circuits were presented. Knowledge of thermal equivalent circuits and electro–thermal models can lead to improved design of GaN HEMT high-power amplifiers with account of instantaneous temperature variations for systems using variable-envelope signals. It can also expand their range of application.

Analysis of Infrared Thermography during Tensile Test of GFRP

2008 ◽  
Vol 47-50 ◽  
pp. 1129-1132
Author(s):  
Jin Woo Kim ◽  
Dong Gi Lee ◽  
Jae Ki Sim ◽  
Jae Yeol Kim ◽  
Seung Hyun Choi
Keyword(s):  
Temperature Distribution ◽  
Crack Propagation ◽  
Tensile Test ◽  
Fiber Orientation ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Ir Thermography ◽  
Lower Maximum ◽  
Lock In

Property of GFRP is naturally dependent on the property of matrix, but receives of temperature effects by external force. Therefore, determination of mechanical property by effect of temperature in GFRP is most crucial factor. In this paper, temperature distribution during crack propagation from temperature change under tensile test was proposed through IR thermography camera. Lock-in thermography method, which is one of technique in IR thermography camera to measure minute change in temperature, was utilized to monitor temperature distribution and change during crack propagation. Method to analyze temperature distribution during crack propagation under tensile test of GFRP via IR thermography camera was suggested. Anisotropy in fiber orientation showed longer fracture time and lower maximum temperature.

scholarly journals Ultrafast chemical imaging by widefield photothermal sensing of infrared absorption

2019 ◽  
Vol 5 (7) ◽  
pp. eaav7127 ◽  
Author(s):  
Yeran Bai ◽  
Delong Zhang ◽  
Lu Lan ◽  
Yimin Huang ◽  
Kerry Maize ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Throughput ◽  
Chemical Imaging ◽  
Photothermal Effect ◽  
Nanometer Scale ◽  
Light Pulses ◽  
Spectral Fidelity ◽  
Speed Up ◽  
Lock In

Infrared (IR) imaging has become a viable tool for visualizing various chemical bonds in a specimen. The performance, however, is limited in terms of spatial resolution and imaging speed. Here, instead of measuring the loss of the IR beam, we use a pulsed visible light for high-throughput, widefield sensing of the transient photothermal effect induced by absorption of single mid-IR pulses. To extract these transient signals, we built a virtual lock-in camera synchronized to the visible probe and IR light pulses with precisely controlled delays, allowing submicrosecond temporal resolution determined by the probe pulse width. Our widefield photothermal sensing microscope enabled chemical imaging at a speed up to 1250 frames/s, with high spectral fidelity, while offering submicrometer spatial resolution. With the capability of imaging living cells and nanometer-scale polymer films, widefield photothermal microscopy opens a new way for high-throughput characterization of biological and material specimens.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

Spectro-mechanical Characterization of Aromaticity and Maturity of Kerogens in Oil Shale at 6 nm Spatial Resolution

2018 ◽  
Author(s):  
Devon Jakob ◽  
Le Wang ◽  
Haomin Wang ◽  
Xiaoji Xu
Keyword(s):  
Spatial Resolution ◽  
Oil Shale ◽  
Infrared Imaging ◽  
Mechanical Characterization ◽  
Optical Diffraction ◽  
Chemical Compositions ◽  
Valuable Insight ◽  
Eagle Ford Shale

<p>In situ measurements of the chemical compositions and mechanical properties of kerogen help understand the formation, transformation, and utilization of organic matter in the oil shale at the nanoscale. However, the optical diffraction limit prevents attainment of nanoscale resolution using conventional spectroscopy and microscopy. Here, we utilize peak force infrared (PFIR) microscopy for multimodal characterization of kerogen in oil shale. The PFIR provides correlative infrared imaging, mechanical mapping, and broadband infrared spectroscopy capability with 6 nm spatial resolution. We observed nanoscale heterogeneity in the chemical composition, aromaticity, and maturity of the kerogens from oil shales from Eagle Ford shale play in Texas. The kerogen aromaticity positively correlates with the local mechanical moduli of the surrounding inorganic matrix, manifesting the Le Chatelier’s principle. In situ spectro-mechanical characterization of oil shale will yield valuable insight for geochemical and geomechanical modeling on the origin and transformation of kerogen in the oil shale.</p>

Fault Localization and Functional Testing of ICs by Lock-in Thermography

2002 ◽  
Author(s):  
O. Breitenstein ◽  
J.P. Rakotoniaina ◽  
F. Altmann ◽  
J. Schulz ◽  
G. Linse
Keyword(s):  
Spatial Resolution ◽  
Electronic Device ◽  
Imaging Techniques ◽  
Heat Diffusion ◽  
Acquisition Time ◽  
Temperature Modulation ◽  
Heat Sources ◽  
Ir Camera ◽  
Free Running ◽  
Lock In

Abstract In this paper new thermographic techniques with significant improved temperature and/or spatial resolution are presented and compared with existing techniques. In infrared (IR) lock-in thermography heat sources in an electronic device are periodically activated electrically, and the surface is imaged by a free-running IR camera. By computer processing and averaging the images over a certain acquisition time, a surface temperature modulation below 100 µK can be resolved. Moreover, the effective spatial resolution is considerably improved compared to stead-state thermal imaging techniques, since the lateral heat diffusion is suppressed in this a.c. technique. However, a serious limitation is that the spatial resolution is limited to about 5 microns due to the IR wavelength range of 3 -5 µm used by the IR camera. Nevertheless, we demonstrate that lock-in thermography reliably allows the detection of defects in ICs if their power exceeds some 10 µW. The imaging can be performed also through the silicon substrate from the backside of the chip. Also the well-known fluorescent microthermal imaging (FMI) technique can be be used in lock-in mode, leading to a temperature resolution in the mK range, but a spatial resolution below 1 micron.

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