Download Finding your thermal solutions in the Heat Lab at Georgia Tech

Measurement. Simulation.
TM
Innovation.
www.heat.gatech.edu
Finding your thermal solutions
in the Heat Lab at Georgia Tech
A Center in the Georgia Institute of Technology
Institute of Electronics and Nanotechnology
Officially open for business in early 2016…
Vision
Heat Lab is global center of
excellence in thermal science
and engineering – we eliminate
heat as a barrier to technology
innovation
Heat Lab in Atlanta
Located on Georgia Tech campus in Midtown Atlanta Website: heat.gatech.edu Numerous world-class faculty and students
to work on your thermal problems
Who is the Heat Lab?
•  Founded: In 2015 by group of Georgia Tech Professors
•  Affiliation: Center in the Georgia Tech Institute for
Electronics and Nanotechnology; secondary affiliation
with the Georgia Tech Strategic Energy Institute and
Institute for Materials
•  Central lab; and assets distributed across Georgia Tech
Working with the Heat Lab
•  Services: Measurement, simulation, technology and
product development
–  Get access to our knowledge and innovation
–  Come tell us your thermal problems
–  Let us hand you a solution (or host an ideation session for you)
–  Let us work with you to implement your solution
–  Come work on your solution in our lab…in Atlanta
Working with the Heat Lab
•  Billing for service: Flexible monthly invoicing or 1+
year contracts
–  Billing on hourly rate based on experience level on project from
student to faculty ($165 to $743/hr + low internal rate for any
equipment use)
•  Students, post docs, research scientists, and faculty at your service
–  Fixed price contract work for longer-term projects
•  Billing for equipment use: Industry user rate $35/hr
for all tools + $200/mo entry fee; includes training and
support costs. Startups with GT licensed technology
pay internal user rate and entry fee is waived.
Working with the Heat Lab
•  Member affiliate: $18,500 annual fee
–  Listed as Heat Lab Member Affiliate on website and marketing
–  Receive annual Heat Lab newsletter
–  Priority access to most recent publications and patents
•  List sent quarterly
–  Priority access to students for recruitment
–  Discounted rates for service and equipment use
•  Gift funding: Opportunity to brand Heat Lab Fellow
positions, colloquium, and core lab; or to provide
general support to the Heat Lab
Heat Lab Leadership and Contacts
•  Dr. Baratunde Cola, Co-Director
([email protected])
•  Dr. Samuel Graham, Co-Director
([email protected])
•  Dr. Shannon Yee, Associate Director
([email protected])
•  Email us about your thermal problems…be an early
partner before we go live in 2016…
Temperature profile on chip simulations
Simulation. Measurement. Innovation.TM
Heat Lab Capabilities
(Examples…)
Spectroscopy and Photoluminescence (Graham Group)
troscopy and photoluminescence are powerful tools for measuring the
and phonon lifetimes in semiconductor devices. We have extensively
to the characterization of Si and GaN based semiconductor devices for rf,
applications. Our lab has multiple micro-Raman systems with laser
g from 325 – 532 nm and spatial resolution down to 500 nm. The systems
f and DC probes for direct measurement of devices, x-y-z mapping capability,
ch range from RT-1200°C, vacuum and environmental control, and chillers
mponents (up to 1700 W). An array of Keithley SMUs and electronic loads
ting devices under DC and pulsed operation.
random
cyclic
Device measurements
global
Material synthesis innovation
20 µm
Licensed product! •  High thermal conduc<vity •  Billions of aligned nanoscale thermal paths Demonstrated 30% improvement over alterna<ve solu<ons Detailed list of equipment and custom simulation assets (18 pgs.)
Tool
Steady-State Meter Bar
Thermal Contact Resistance Measurement Facility
Thermo-mechanical Burn-in Tester
Group
B. Cola
B. Peterson
Tool
GT Cryo Lab 4 K Dewar and Wave Generator Test
Apparatus
High-Vacuum Cryogenic Stage
Group
M. Ghiaasiann
M. Ghiaasiann
B. Cola
High-Temperature Emissometry Facility
Z. Zhang
Interfacial Adhesion and Interfacial Thermal
Resistance of Thermal Interface Materials
S. Sitaraman
Fourier Transform Infrared Spectroscopy
Z. Zhang
Nano UTM and Nanoindenter
S. Sitaraman
Integrating sphere system
Z. Zhang
Z. Zhang
A. Henry
Transient Plane Source
Time-Domain Thermoreflectance (TDTR)
B. Cola
B. Cola
Photoacoustic
B. Cola
Three-Axis Automated Scatterometer (TAAS)
Thermogravimetric Analyzer and Differential Scanning
Calorimeter
Micro Particle Image Velocimetry (µμPIV)
3-Omega Technique
S. Yee
High Speed Camera
Y. Joshi
Frequency-Domain Thermoreflectance (FDTR)
S. Yee
Room level PIV measurement capability
Y. Joshi
Thermal Conductivity of Individual Micro/Nano
Materials
Measurement Facility
Environmental Testing and Analysis
B. Peterson
Mobile thermocouple grids for thermal mapping
Y. Joshi
S. Graham
Home-made Simulation Capabilities for Radiative
Properties
Z. Zhang
Enhanced Surfaces for Two Phase Heat Transfer
S. Graham
First Principles Based Modeling of Thermal Transport
Properties
A. Henry
Enhanced Boiling Heat Transfer
B. Peterson
First Principle Methodology for Prediction of Thermal
Properties
S. Kumar
Y. Joshi
Thermal Management and Electro-Thermal Transport
Study of Electronic Devices
S. Kumar
Micro-IR Thermal Imaging
Micro-Raman Spectroscopy and Photoluminescence
S. Graham
Y. Joshi
Thermal Characterization Tools for Discovery and Applications
Steady-State Meter Bar (Cola Group)
Thermal Contact Resistance Measurement Facility (Peterson Group)
We employ a modified version of the ASTM D-5470 standard for measuring thermal conductivity
and thermal contact resistance. The modification enables improve measurement reproducibility and
accuracy when combined with high precision thermocouples. The technique is used to characterize
the performance of advanced thermal interface materials. The pressure applied to the material can be
controlled to understand the interplay between interface contact mechanics and thermal contact
resistance.
The thermal contact resistance/conductance can be measured using a custom built apparatus using
improvements to the ASTM test standard D-5470. The contact pressure can be varied varies from 0.1
to 2 MPa and the thermal contact resistance can be measured to a accuracy of 0.5 mm2K/W. The
samples can be prepared from thin films, sheets, metallic foils or bulk materials with moderate to
high thermal conductivity, as well as advanced nanowires or nanotubes array based thermal interface
materials.
This technique can be used to:
•
•
•
•
Standardize measurement of thermal interface materials
Explore novel nanomaterials as advanced thermal interface materials
Measure thermal conductivity of bulk materials
Measure Seebeck coefficient and power factor of thermoelectric materials
References:
D.R. Thompson, S.R. Rao, and B.A. Cola. “A Stepped-Bar Apparatus for Thermal Resistance
Measurements.” ASME Journal of Electronic Packaging, 135:041002, 2013.
References:
Feng, B., F. Fardin, P. Bao, A. T. Chien, S. Kumar and G. P. Peterson, “Gecko-Feet Inspired Tin
Nanowire Arrays for Advanced Thermal Interface Materials,” Applied Physics Letters, vol. 102,
093105 2013
Thermo-mechanical Burn-in Tester (Cola Group)
We employ a custom device burn-in tester that is modeled after the needs of several industries. The
system employs a pneumatically actuated water block and copper heaters to measure the thermal
conductance across an interface under dynamic loading.
Rev
A
B
Customer Specification
Description
Preliminary release.
Various updates.
Date
By
08/23/12
08/27/12
RF
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753 Test Fixture
Interfacial Adhesion and Interfacial Thermal Resistance of Thermal
Interface Materials (Sitaraman Group)
Test Resources™ Model 100P system to measure the interfacial fracture toughness of thermal
interface materials (TIMs) over a wide range of mode mixity. The objective is to understand how
filler particles enhance thermal conductivity, and at the same time, influence interfacial fracture
toughness. This tool will be helpful to provide insight into the relationship between filler particles to
interfacial fracture toughness to interfacial thermal resistance. TestResources Model 100P with R
controller universal tester is a high-speed data acquisition (1100 data points/sec) with load or
displacement control. The software control allows for multi-step segments (mix ramp, dwells
sinusoidal, saw-tooth, modes, and blocks).
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Drawing Number:
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•
Nano UTM and Nanoindenter (Sitaraman Group)
fax 408-782-7132
Rev.
B
Page:
1 of 4
Customer Specification
This technique can be used to:
•
Measure the time varying interfacial resistance of a variety of materials under conditions
including:
o Mechanical cycling
o Constant pressure thermal cycling
Evaluate the durability and wear resistance of materials subjected to dynamic loading.
References:
M.R. Maschmann, B.A. Cola, M. Haller, and C. Henry. Characterization of Carbon Nanotube-Coated
Foil TIM during Burn In Testing. Proceedings of Intel Design and Test Technology Conference,
Chandler, AZ, 2008.
B.A. Cola, M.R. Maschmann, C. Henry, and T.S. Fisher. Copper Foil/Carbon Nanotube Array
Thermal Interface Materials used For CPU Burn-In. Proceedings of VMIC-VLSI/ULSI Multilevel
Interconnect Conference, Fremont, CA, 2007.
These tools will help to provide mechanics-based understanding of compliant metallic structures and
CNTs for thermal management purposes. The objective is to understand the relationship between
CNT and metallic nanowire structures and their mechanical, thermal, and electrical properties
through computer-based models and experimental characterization. The below figure is Si/CNT/Si
sandwich sample for modulus testing using Berkovich tip and loading/unloading rate of 700 nm/s.
Triboindenter Tip
Si
SU8®
VACNTs
Si
References:
1. Ginga, N. J., Chen, W., and Sitaraman, S. K., “Waviness reduces effective modulus of carbon
nanotube forests by several orders of magnitude,” Carbon, Volume 66, January 2014, pp. 57–66.
2. Ginga, N. J. and Sitaraman, S. K., “The experimental measurement of effective compressive
modulus of carbon nanotube forests and the nature of deformation,” Carbon, Volume 53, March
2013, pp. 237–244
Transient Plane Source (Cola Group)
Time-Domain Thermoreflectance (TDTR) (Cola Group)
The commercial system Hot Disk TPS 2500 S, which meets an ISO standard (ISO/DIS 22007-2.2),
can measure thermal conductivity of solids, liquids, and composites. The system is compatible with
Tenney Jr. environmental test chamber for thermal property and reliability assessment from -75 to
200 °C.
Time-Domain thermoreflectance is a non-contact optical method for measuring the thermal
conductivity, heat capacity, and thermal resistance of thin-films and interfaces. It utilizes ultra-short
laser pulses, <100 fs in duration at a repetition rate of 80 MHz, to characterize thermal transport at
nanometer length scales. A liquid Helium cryostat enables measurements over a wide temperature
range, 8 to 500 K, to develop a better understand of the fundamental phonon scattering processes
within materials and across interfaces.
This technique can be used to:
•
•
Determine the thermal conductivity of powders/packed particle beds, liquids, bulk solids, and
composites from -75 to 200 °C
Measure in-plane and through-plane thermal conductivity of anisotropic materials
References:
S. E. Gustafsson, "Transient Plane Source Techniques for Thermal-Conductivity and ThermalDiffusivity Measurements of Solid Materials," Review of Scientific Instruments, 62:797-804. 1991.
This technique can be used to:
• Characterize nanoscale thermal transport, with applications in thermal management of
electronics
• Study carrier (electron and phonon) thermalization and coupling
• Characterize the thermal properties of complex multilayer nanostructures, such as
superlattices
• Understand phonon frequency contributions to thermal conductivity and thermal interface
conductance
• Determine the thermal properties of nanostructures and nanostructure contacts
References:
B. C. Gundrum, D. G. Cahill, and R. S. Averback, "Thermal conductance of metal-metal interfaces,"
Physical Review B. 72. 2005.
M. D. Losego, M. E. Grady, N. R. Sottos, D. G. Cahill, and P. V. Braun, "Effects of chemical
bonding on heat transport across interfaces," Nature Materials, 11:502-506. 2012.
Photoacoustic (Cola Group)
3-Omega Technique (Yee Group)
The photoacoustic technique is a method to extract thermal properties from thin film and bulk
samples. The technique involves periodic laser heating and indirect probing of sample temperature
through sensing the pressure change generated in an enclosed volume of gas above the sample
surface.
The 3-Omega technique is used to very accurately measure the thermal properties of materials. It is
most commonly used to measure the through-plane thermal conductivity of thin-films (10 nm – 100
µm) from 10 K to 800 K, but it can also measure thermal diffusivity and effusivity directly. It can
also be used to measure ultra-low thermal conductivities (<0.01 W/m-K) of solids, liquids, and gases.
This technique can be used to:
• Characterize nanoscale thermal transport, with applications in thermal management of
electronics
This technique can be used to:
• Measure the thermal conductivity of novel alloys, semiconductors, polymers, and glasses
• Determine the through-plane thermal resistance of complicated composites
• Determine the thermal properties of tissues and other soft matter
• Distinguish between gas mixtures and liquid mixtures via their phase response
• Quantify small heat fluxes from endothermic or exothermic surface reactions
•
•
Measure the thermal properties of thin-films, interfaces, and nanostructures
Measure the thermal properties of buried layers and interfaces
References:
X. Wang, B.A. Cola, T.L. Bougher, S.L. Hodson, T.S. Fisher, and X. Xu. Photoacoustic Technique
for Thermal Conductivity and Thermal Interface Measurements. Chapter in Annual Review of Heat
Transfer, issue 16:135-157, 2013.
B.A. Cola, J. Xu, C. Cheng, H. Hu, X. Xu, and T.S. Fisher. Photoacoustic Characterization of Carbon
Nanotube Array Thermal Interfaces. Journal of Applied Physics, 101:054313, 2007.
References:
D. G. Cahill, “Thermal Conductivity Measurement from 30 to 750 K: The 3ω Method,” Review of
Scientific Instruments, 61, No. 2, 1990.
C. Dames and G. Chen, “1ω, 2ω and 3ω methods for measurement of thermal properties,” Review of
Scientific Instruments, 76, 124902, 2005.
Frequency-Domain Thermoreflectance (FDTR) (Yee Group)
Thermal Conductivity of Individual Micro/Nano Materials
FDTR measures the heat capacity or thermal conductivity of bulk and thin-film materials. This
FDTR setup is specifically designed to measure both the in-plane and through-plane thermal
conductivity with spot sizes ~50 µm. This technique is designed for heating modulation rates up to
200 MHz and can determine what nanoscale lengths most effectively reduce the thermal conductivity
in exotic and novel materials. The setup also has a method of optically simulating complex heating
patterns and measuring the temperature rise at various locations within that pattern. Finally, this
technique is instrumented with a single-element interferometer and can resolve small changes in
photoluminescense or Raman signatures from heating.
Measurement Facility (Peterson Group)
This technique can be used to:
• Probe thermal transport of highly anisotropic materials, such as multilayers, superlattices,
and polymers
• Characterize nanoscale thermal transport, with applications in thermal management of
electronics
• Measure the thermal conductivity accumulation function to determine the dominant
engineering length scales that reduce the thermal conductivity
• Simulate complex microscale heating profiles on surfaces and observe where the heat flows
References:
K. T. Regner, D. P. Sellan, Z. Su, C. H. Amon, A. McGaughey, and J. A. Malen, “Broadband phonon
mean free path contributions to thermal conductivity measured using frequency domain
Thermoreflectance,” Nature Communications, 4, 1640, 2013.
C. B. Saltonstall, J. Serrano, P. M. Norris, P. E. Hopkins, and T. E. Beechem, “Single Element
Raman Thermometry,” Review of Scientific Instruments, 84, 064903, 2013.
This specially designed cryogenic (77–500 K) vacuum system (10-5 torr) can be used to measure the
axial thermal conductivity of single micro/nano wires, fibers, nanotubes (nanotube bundles) or inplane thermal conductivity of micro composite films. It employs a four probe dc thermal bridge
method. The samples can be either conductive or non-conductive materials. The heat capacity can
also be determined for these test articles if a transient power source is utilized.
References:
Moon, J, Weaver, K., Feng, B., Chae, H. G., Kumar, S., Baek, J. and Peterson, G. P., “Thermal
Conductivity Measurement of Individual PEK/CNT Fibers Using a Steady-State DC Thermal Bridge
Method," Review of Scientific Instruments,” 2012, vol. 83, 016103
Feng B, Ma WG, Li Z X, Zhang X. “Simultaneous measurements of the specific heat and thermal
conductivity of suspended thin samples by transient electrothermal method”, Review of Scientific
Instruments, 2009, vol. 80, 064901
Chien, A. T., Gulgunje, P. V., Chae, H. G., Joshi, A., Moon, J.Feng, B. and Peterson, G. P. and
Kumar, S., “Functional polymer–polymer/carbon nanotube bi-component Fibers,” Polymer, vol. 54,
2013, pp. 6210-6217.
Feng, B, Li, Z., Zhang, X. and Peterson, G. P., “Numerical Approach for the Theory of Harmonic
Self-heating Technique to Measure Thermophysical Properties of Suspended Thin Samples,” J. Vac.
Sci. Technology, vol. 27, no. 5, 2009, pp. 2280-2285.
Environmental Testing and Analysis (Graham Group)
Enhanced Surfaces for Two Phase Heat Transfer (Graham Group)
We have environmental chambers for testing the thermal and environmental response of electronic
devices and materials. Techniques such as electrical resistance thermometry can be applied to
devices while exposed to elevated temperature and humidity conditions or while in a nitrogen filled
glove box. The systems include a Cincinnati SubZero MicroClimate humidity chamber with 10200°C and 5-100% RH and a MBraun glove box with oxygen and water vapor partial pressures
below 0.5 ppm.
We develop coatings for the enhancement of two phase heat transfer from surfaces and characterize
them through pool boiling experiments, contact angle measurements, scanning electron microscopy,
and other methods to understand fluid-surface interactions. The goal is to create enhanced surfaces to
improve heat dissipation from electronic devices through two phase heat transfer in dielectric and
polar liquids.
This technique can be used to
• Measure onset of nucleate boiling and critical heat flux of engineered surfaces.
• Test the durability of coatings through long term pool boiling.
• Test over a range of pressures above and below atmospheric conditions.
• Fluids include Water, FC-72, n-pentane, HFE-7200.
• High speed camera for video capture and analysis.
Enhanced Boiling Heat Transfer (Peterson Group)
Micro-IR Thermal Imaging (Joshi Group)
Boiling heat transfer has the capability of removing large amounts of thermal energy, due to the
phase change process. A test facility has been designed and build to test and evaluate two novel
approaches recently developed to augment the boiling heat transfer coefficient and the critical heat
flux: on atomic layer deposited surfaces coated with Aluminum Oxide and modified surfaces with
nanoparticle cluster coatings of Aluminum Oxide and Iron Oxide. This facility provides the
capability to investigate the pool boiling heat transfer performance. Additional equipment including
contact angle measurement, UV-Vis spectrophotometer, ellisopmeter, high-speed camera are all
available to assist in the characterization of the sample quality and heat transfer performance.
IR thermal imaging is used to measure the thermal response of devices and materials. The system
consists of a Quantum Focus IR Microscope with liquid nitrogen cooled detectors. A spatial
resolution down to 3 µm and a temperature resolution of 0.1K are possible with this system.
Referen
ces:
Feng, B., Weaver, K. and Peterson, G. P., “Enhancement of Critical Heat Flux in Pool Boiling Using
Atomic Layer Deposition of Alumina" Applied Physics Letters, vol. 100, Issue 5, 053120, 2012
References:
A. McNamara, V. Sahu, Y. Joshi, Z. Zhang. “Infrared Imaging Microscope as an Effective Tool for
Measuring Thermal Resistance of Emerging Interface Materials”. Proc. of ASME/JSME Therm Engin
Joint Conf. 2011.
C. H. Oxley, R. H. Hopper, G. Hill, and G. A. Evans, "Improved infrared (IR) microscope
measurements and theory for the micro-electronics industry," Solid-State Electronics, 54:63. 2010.
Micro-Raman Spectroscopy and Photoluminescence (Graham Group)
Micro-Raman spectroscopy and photoluminescence are powerful tools for measuring the
temperature, strain, and phonon lifetimes in semiconductor devices. We have extensively applied
these tools to the characterization of Si and GaN based semiconductor devices for rf, power, and LED
applications. Our lab has multiple micro-Raman systems with laser wavelengths ranging from 325 –
532 nm and spatial resolution down to 500 nm. The systems are equipped with rf and DC probes for
direct measurement of devices, x-y-z mapping capability, thermal stages which range from RT1200°C, vacuum and environmental control, and chillers for heat sinking components (up to 1700
W). An array of Keithley SMUs and electronic loads are available for testing devices under DC and
pulsed operation.
This technique can be used to:
• Measure the temperature distribution in electronic devices.
• Determining the strain/stress in devices.
• Determining the interfacial thermal resistance in heteroepitaxial systems.
• Measuring phonon lifetimes in materials.
References:
Choi, S., et al., Analysis of the residual stress distribution in AlGaN/GaN high electron mobility
transistors. Journal of Applied Physics, 2013. 113(9).
Choi, S., et al., The impact of mechanical stress on the degradation of AlGaN/GaN high electron
mobility transistors. Journal of Applied Physics, 2013. 114(16).
Choi, S., et al., The impact of bias conditions on self-heating in AlGaN/GaN HEMTs. IEEE
Transactions on Electron Devices, 2013. 60(1): p. 159-162.
Heller, E., et al., Electrical and structural dependence of operating temperature of AlGaN/GaN
HEMTs. Microelectronics Reliability, 2013. 53(6): p. 872-877.
Beechem, T., et al., Micro-Raman thermometry in the presence of complex stresses in GaN devices.
Journal of Applied Physics, 2008. 103(12).
Beechem, T., et al., Assessment of stress contributions in GaN high electron mobility transistors of
differing substrates using Raman spectroscopy. Journal of Applied Physics, 2009. 106(11).
Beechem, T. and S. Graham, Temperature and doping dependence of phonon lifetimes and decay
pathways in GaN. Journal of Applied Physics, 2008. 103(9).
Beechem, T., et al., Invited Article: Simultaneous mapping of temperature and stress in microdevices
using micro-Raman spectroscopy. Review of Scientific Instruments, 2007. 78(6).
Hsu, S.C., et al., Stress relaxation in GaN by transfer bonding on Si substrates. Applied Physics
Letters, 2007. 91(25).
Lee, J., et al., Electrical, thermal, and mechanical characterization of silicon microcantilever
heaters. Journal of Microelectromechanical Systems, 2006. 15(6): p. 1644-1655.
GT Cryo Lab 4 K Dewar and Wave Generator Test Apparatus (Ghiaasiann
Group)
This is a fully-instrumented 9 ft3 vacuum space (27 inch diameter), cooled by Gifford-McMahon
(GM)-type Cryocooler that does not need a liquid cryogens. The cryocooler (Sumitomo RDK-408D2)
can provide 1 W cooling power at 4 K temperature (Stage II) ; and 50 W cooling power at 43 K
(Stage I). The dewar is equipped with Insulated liquid and Instrumentation feed-throughs, an 8channel PID temperature controller, and a calibrated thermal bus bar. The dewar has 360° single axis
rotation capability. The dewar can be fed with a 500 W, 40 cc-displacement wave generator
(Qdrive 2S123W).
The test apparatus can be used for measurement of thermal properties as well as flow resistance
parameters at cryogenic temperatures.
High-Vacuum Cryogenic Stage (Ghiaasiann Group)
High-Temperature Emissometry Facility (Zhang Group)
This home-designed high-vacuum cryogenic stage is able to measure thermal conductivities and
emissivity of varies samples under cryogenic temperatures down to 77 K in high vacuum
environment. The external vacuum pump maintains the vacuum level in the camber (down to 10-7
torr) and liquid nitrogen cools the sample stage. A ZnSe window on the side of the camber allows the
characterization of emissivity for nano/micro structures at elevated temperatures. Right now this
system is setup for a near-field radiative heat transfer measurement between two close surfaces under
room temperatures.
The optical layout of the high-temperature emissometry facility includes a heater assembly,
blackbody source, optical components, and FT-IR, which was used to collect the emission spectra
from either the sample or the blackbody. This home-made system is used to directly measure thermal
emittance at temperatures ranging from 300 to 1000 K.
References:
Basu, S., Lee, B.J., and Zhang, Z.M., 2010, “Near-Field Radiation Calculated with an Improved
Dielectric Function Model for Doped Silicon,” Journal of Heat Transfer, Vol. 132, 023302-1/7.
References:
Wang, L.P., Basu, S., and Zhang, Z.M., 2012, “Direct Measurement of Thermal Emission from a
Fabry-Perot Cavity Resonator,” Journal of Heat Transfer, Vol. 134, p. 072701-1/9.
Fourier Transform Infrared Spectroscopy (Zhang Group)
Integrating sphere system (Zhang Group)
An ABB Bomem MB154S Fourier-transform infrared (FTIR) spectrometer is available for thermal
emittance, transmittance and reflectance measurements in the wavelength region from 0.72 to 20 µm
(14,000 – 500 cm–1). The FTIR is equipped with purge inlets, a ceramic global source, and a
pyroeletric detector.
An integrating sphere allows the directional-hemispherical thermal emittance and reflectance to be
measured in the visible and near infrared regions. The 8 inch diameter sphere is coated with PTFE
(polytetrafluoroethylene).
References:
Wang, H., Liu, X.L., and Zhang, Z.M., 2013, “Absorption Coefficient of Crystalline Silicon at
Wavelengths from 500 nm to 1000 nm,” International Journal of Thermophysics, Vol. 34, pp. 213225.
Wang, X.J., Haider, A.M., Abell, J.L., Zhao, Y.-P., and Zhang, Z.M., 2012, “Anisotropic Diffraction
from Inclined Silver Nanorod Arrays on Grating Templates,” Nanoscale and Microscale
Thermophysical Engineering, Vol. 16, pp. 18-36.
References:
Wang, L.P., and Zhang, Z.M., 2013, “Measurement of Coherent Thermal Emission due to Magnetic
Polaritons in Subwavelength Microstructures,” Journal of Heat Transfer, Vol. 135, p. 091014-1/9.
Basu, S., Lee, B.J., and Zhang, Z.M., 2010, “Infrared Radiative Properties of Heavily Doped Silicon
at Room Temperature,” Journal of Heat Transfer, Vol. 132, 023301-1/8.
Wang, L.P., Lee, B.J., Wang, X.J., and Zhang, Z.M., 2009, “Spatial and Temporal Coherence of
Thermal Radiation in Asymmetric Fabry-Perot Resonance Cavities,” International Journal of Heat
and Mass Transfer, Vol. 52, pp. 3024-3031.
Wang, X.J., Flicker, J.D., Lee, B.J., Ready, W.J., and Zhang, Z.M., 2009, “Visible and Near-Infrared
Radiative Properties of Vertically Aligned Multi-Walled Carbon Nanotubes,” Nanotechnology, Vol.
20, 215704-1/9.
Three-Axis Automated Scatterometer (TAAS) (Zhang Group)
A Three-Axis Automated Scatterometer (TAAS) facility has been developed for measuring
bidirectional reflectance/transmittance distribution function. The goniometric table is composed of
three rotary stages with high angular resolution (0.005 degree) and repeatability (0.0006 degree). A
lock-in amplifier or a mechanical chopper combined with pre-amplifiers of a large dynamic range can
avoid the background radiation. The sample holder allows a large sample up to 300 mm diameter to
be measured. A heated sample holder can be included in the system for measurements at the elevated
temperature.
Thermogravimetric Analyzer and Differential Scanning Calorimeter (Henry
Group)
Thermogravimetric analysis (TGA) is a method for measuring mass change of a sample under
temperatures and gaseous atmospheres of interest. A 1µg resolution scale affixed inside a high
temperature furnace is used to resolve the mass gains or losses which resulting from chemical
reaction or phase changes at temperatures as high as 2000°C. A differential scanning calorimeter
(DSC) is a device that determines the heat absorbed or released by a sample. It is used to measure
specific heat, latent heat of phase change, and reaction enthalpies. The simultaneous measurement of
TGA and DSC signals quickly constructs an enhanced description of the process under examination.
Oxidation and Reduction measurements:
Specifically designed for detail redox reaction analysis, auxiliary gas handling and monitoring
equipment enables high resolution control of oxidizing and reducing environments. By controlled
mixing of buffer gasses, this equipment enables testing under controlled oxygen partial pressures
ranging from 1atm down to 10-25 atm at high temperatures.
References:
Wang, X.J., Abell, J.L., Zhao, Y.-P., and Zhang, Z.M., 2012, “Angle-Resolved Reflectance of
Obliquely Aligned Silver Nanorods,”Applied Optics, Vol. 51, 1521-1531.
Wang, X.J., Wang, L.P., Adewuyi, O.S., Cola, B.A., and Zhang, Z.M., 2010, “Highly Specular
Carbon Nanotube Absorbers,” Applied Physics Letters, Vol. 97, 163116-1/3.
Testing Parameters:
• Oxidizing environments up to 1650°C
• Inert environments up to 2000°C
• Water vapor environments up to 1250°C
Micro Particle Image Velocimetry (𝛍𝐏𝐈𝐕) (Joshi Group)
High Speed Camera (Joshi Group)
Particle Image Velocimetry (PIV) is a non-intrusive laser optical measurement technique for research
and diagnostics into flow, turbulence, microfluidics, spray atomization and combustion processes.
Standard PIV measures two velocity components in a plane (2D2C) using a single CCD camera. It
has up to 100x optical magnification of measurement. The size of fluorescent seeding particle is
down to 100nm. And the time resolved measurements is up to 10kHz.
High-speed camera is a device used for recording fast-moving objects as a photographic image(s)
onto a storage medium. After recording, the images stored on the medium can be played back in
slow-motion. The Phantom v211 high speed camera is equipped with widescreen 1280 x 800 CMOS
sensor – which is 25 percent wider than most competitive models. This allows to keep moving targets
in the frame longer and see more of the event. The wide sensor also enables true 1280 x 720 HD
images. The v211 delivers a maximum speed of 2190 frames-per-second at full resolution. At
reduced resolutions, it can deliver up to 300,000 frames-per-second, further underscoring its
versatility.
This technique can be used to:
• Experiments simulating microfluidic flow.
• Validation and test of flows in MEMS.
• Design and development of lab-on-a-chip devices
• Two-phase flow microsystems (droplet or bubble dispensers)
This technique can be used to:
•
References:
L. Gong, K. Kota, W. Tao, and Y. Joshi, “ Thermal performance of microchannels with wavy walls
for electronics cooling,” IEEE Transactions on Components, Packaging and Manufacturing
Technology, Vol. 1(7), 2011.
Two-phase flow in microchannel: observe condensation and bubble generation.
Room level PIV measurement capability (Joshi Group)
Mobile thermocouple grids for thermal mapping (Joshi Group)
Particle image velocimetry (PIV) system is a unique capability, which is used for large scale air
flowfield characterization in the data center laboratory. Air emerging from the perforated tile is
seeded with water based fog particles from a theatrical fog generator (F-100). The plane of
measurement is illuminated with laser light sheet (200 mJ/pulse, pulse = 10 ns, λ = 532 nm, thickness
~ 3mm) and the scattered light is captured on two Flow Sense cameras (1600 × 1186 pixels)
adjacently placed, so as to cover the width of the tile. The laser and the cameras are fixed on a
vertical traverse system and the entire system is moved along the height of the rack to measure the
velocity field at multiple positions. Finally, the obtained velocity field is stitched together to obtain a
complete velocity field in the measurement plane. Thermal field in air cooled data centers can be measured using a 3D array of “T-type” thermocouples
(wire diameter = 0.01”) populated on a mobile grid. The width of the deployed cart is about 122cm
(4ft) covering the full width of the cold aisle. The depth is 61cm (2ft) covering one standard
perforated tile and the height of the cart is 198cm (6ft 6inch) reaching the height of a standard 42U
(1U = 4.45cm) rack. There are total 256 thermocouples on the mobile grid which are mounted in 9
planes along the width, 5 planes along the depth and 6 planes along the height of the grid. Complete
3D mapping of the cold aisle can be performed by stitching together the acquired data along the
length of the aisle.
References:
[1] Kumar, P., Joshi, Y., Experimental Investigations on the Effect of Perforated Tile Air Jet Velocity
on Server Air Distribution in a High Density Data Center, Intersociety Conference on Thermal
and Thermomechanical Phenomena in Electronic Systems (ITherm), Jun 2-5, 2010, Las Vegas,
Nevada, USA.
References:
[1] Arghode, V. K., Sundaralingam, V., Joshi, Y., Phelps, W., Thermal Characteristics of Open and
Contained Data Center Cold Aisle, ASME Journal of Heat Transfer, v 135, p 061901-1-11, 2013.
Thermal Property Prediction and Design using Custom Simulation
Home-made Simulation Capabilities for Radiative Properties
(Zhang Group)
First Principle Methodology for Prediction of Thermal Properties (Kumar
Group)
Our lab has developed exact method to calculate near-field radiative heat transfer for anisotropic
materials, one-dimensional gratings (based on scattering theory), and arbitrary three-dimensional
particles (based on discrete dipole approximation), and there are no commercial software available
for characterizing near-field heat flux.
Atomistic models can be employed to analyze the phonon transport and predict the thermal properties
of nano-structures and their interfaces. Phonon transport has been explored using atomistic simulation
methods such as Molecular Dynamics (MD) and Atomistic Green's Function Method (AGF). The
fundamental transport mechanism has been investigated in a broad range of nano-materials such as
graphene, nanotubes, and polymers which are promising to revolutionize the performance and
efficiency of next generation flexible displays, transparent electrodes, bio-chemical sensors, solar
cells, etc. Density functional theory calculations has been performed to determine interfacial bonding,
and AGF and MD simulations has been performed to study the effects of bonding on various thermal
properties, e.g., thermal conductivity of graphene, and phonon transmission and thermal boundary
conductance at graphene/metal interfaces.
References:
Liu, X.L. and Zhang, Z.M., 2014, “Graphene-assisted near-field radiative heat transfer between
corrugated polar materials,” Applied Physics Letters, accepted.
Liu, X.L., Zhang, R.Z., and Zhang, Z.M., 2014, "Near-Field Radiative Heat Transfer with DopedSilicon Nanostructured Metamaterials," International Journal of Heat and Mass Transfer, Vol. 73,
pp. 389-398.
First Principles Based Modeling of Thermal Transport Properties (Henry
Group)
Atomistic simulations have shown remarkable applicability in materials characterization and
understanding. Specifically when informed by information extracted from first principles
calculations, atomistic level modeling can offer predictive and high throughput screening capabilities
[1]. In this respect, molecular dynamics (MD) simulations, using recently developed analysis
techniques within the Atomistic Simulation & Energy (A.S.E.) research group, can be used to predict
and understand the thermal conductivity and thermal interface conductance between different
materials. Using GT supercomputing facilities, such as the partnership for an advanced computing
environment (PACE), and publicly available NSF funded resources such as the STAMPEDE cluster,
the A.S.E. research group can characterize the thermal properties of virtually any material system
from first principles [2]. Such data is crucial for future advanced engineering design and applications
involving thermal transport [3].
1.
2.
3.
Cahill, D.G., et al., Nanoscale thermal transport. II. 2003–2012. Applied Physics Reviews,
2014. 1(1): p. 011305.
Henry, A.S. and G. Chen, Spectral phonon transport properties of silicon based on molecular
dynamics simulations and lattice dynamics. Journal of Computational and Theoretical
Nanoscience, 2008. 5(2): p. 141-152.
Dresselhaus, M., et al., New composite thermoelectric materials for energy harvesting
applications. JOM, 2009. 61(4): p. 86-90.
Modeling Tools: Molecular Dynamics (MD), Atomistic Green's Function (AGF) Method, Density
Functional Theory (DFT), Multi-scale Modeling
•
•
•
•
Estimation of thermal conductivity of 2D materials, polymers and nano-structured materials
Prediction of phonon properties (dispersion curves, phonon lifetimes) of nano-materials
Determination of interfacial boundary resistance
Multi-scale model for electro-thermal transport analysis in devices and systems
References:
Liang Chen, Zhen Huang, and Satish Kumar. “Phonon Transmission and Thermal Conductance
across Graphene/Cu Interface”. Applied Physics Letters 103(12), 4821439, 2013
Liang Chen and Satish Kumar. “Thermal Transport in Graphene Supported on Copper”. Journal of
Applied Physics 112(4), 043502, 2012
Liang Chen and Satish Kumar. “Thermal Transport in Double Wall Carbon Nanotubes Using Heat
Pulse”. Journal of Applied Physics, 110(7), 074305, 2011
Gupta, M. P., Liang, C., Estrada, D., Behnam, A., Pop, E., and Kumar, S.., “Impact of Thermal
Boundary Conductances on Power Dissipation and Electrical Breakdown of Carbon Nanotube
Network Transistors,” Journal of Applied Physics, 112, 124506, 2012
Thermal Management and Electro-Thermal Transport Study of Electronic
Devices (Kumar Group)
The cooling strategies applied in high performance computing systems may be driven by the peak
temperatures on the electronic chip, which corresponds to the transient and localized hot spots (high
heat flux regions) generated by highly non-uniform power dissipation on the chip on both the
temporal and spatial scales. We explored different energy-efficient strategies for thermal gradient
management on the chip: power multiplexing and ultra-thin thermoelectric coolers (TECs) in addition
to convection based cooling. Such studies provided insights to enhance the energy efficiency of the
system and to boost system performance, increase system reliability and enhance the operating life of
the electronic circuits.
We investigated the dynamical change of the locations of active cores (power multiplexing)
within the chip at fixed time intervals for hot spot thermal management. This investigation developed
a transient thermo-fluidics model of a multi-core electronics package and its cooling solution. This
work revealed the thermal physics behind the power multiplexing technique and to establish the
relative effectiveness of different migration policies in reducing the spatial non-uniformity and peak
temperature on the chip. The study shown that an appropriate migration policy can be designed,
which can lead to up to 10 oC reduction in peak temperature for a multi-core processor chip with
typical power input.
We investigated the effects of steady state and transient mode operation of ultrathin TEC devices
on hot spot cooling inside a micro-electronics package. This work quantified the effect of thermal and
electrical contact resistances, and establishes that parasitic contact resistances play a crucial role in
the performance of TEC devices and that significant attention is required to reduce these contact
resistances for energy efficient Peltier cooling. We also explored the application of ultrathin thermoelectric devices for 3D stacked chips and have shown that TECs can be effective in hotspot thermal
management for 3-D packages.
References:
Gupta, M. P., Cho, M., Mukhopadhyay, S., and Kumar, S., “Thermal Investigation into Power
Multiplexing for Homogeneous Many-Core Processors,” Journal of Heat Transfer, 134, 061401,
2012. (Also in the Electronics Cooling Magazine in Dec. 2013)
Matthew, R., and Kumar, S., “Optimization of Thermoelectric Coolers for Hotspot Cooling in 3D
Stacked Chips,” ASME Journal of Electronic Packaging, 137, 011006, 2015.
Matthew, R., Manickaraj, K., Sullivan, O., Mukhopadhyay, S. and Kumar, S., “Hotspot Cooling in
Stacked Chips using Thermoelectric Coolers,” IEEE Transactions on Components and Packaging
Technologies, 3 (5), 759-767, 2013.
Gupta, M. P., Sayer, M., Mukhopadhyay, S., and Kumar, S., “Ultrathin Thermoelectric Devices for
On-Chip Peltier Cooling,” IEEE Transactions on Components and Packaging Technologies, 1 (9),
1395-1405, 2011