Ultrafast thermoreflectance techniques for measuring thermal conductivity and interface thermal conductance of thin films

2010 ◽  
Vol 108 (9) ◽  
pp. 094315 ◽  
Author(s):  
Jie Zhu ◽  
Dawei Tang ◽  
Wei Wang ◽  
Jun Liu ◽  
Kristopher W. Holub ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Thermal Conductance ◽  
Interface Thermal Conductance

Frequency-Domain Thermoreflectance Technique for Measuring Thermal Conductivity and Interface Thermal Conductance of Thin Films

2010 ◽  
Author(s):  
Jie Zhu ◽  
Dawei Tang ◽  
Wei Wang ◽  
Jun Liu ◽  
Ronggui Yang
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Frequency Domain ◽  
Layer Structure ◽  
Modulation Frequency ◽  
Critical Role ◽  
Thermal Conductance ◽  
Dissimilar Materials ◽  
Conductivity Of Thin Films ◽  
Interface Thermal Conductance

The thermal conductivity of thin films and interface thermal conductance of dissimilar materials play a critical role in the functionality and the reliability of micro/nano-materials and devices. The transient thermoreflectance methods, including the time-domain thermoreflectance (TDTR) and the frequency-domain thermoreflectance (FDTR) techniques are excellent approaches for the challenging measurements of interface thermal conductance of dissimilar materials. A theoretical model is introduced to analyze the TDTR and FDTR signals in a tri-layer structure which consists of metal transducer, thin film, and substrate. Such a tri-layer structure represents typical sample geometry in the thermoreflectance measurements for the thermal conductivity and interface thermal conductance of thin films. The sensitivity of TDTR signals to the thermal conductivity of thin films is analyzed to show that the modulation frequency needs to be selected carefully for a high accuracy TDTR measurement. However, such a frequency selection is closely related to the unknown thermal properties and consequently hard to make before the measurement. Fortunately this limitation can be avoided in FDTR. Depending on the modulation frequency, the heat transport in such a tri-layer could be divided into three regimes based on the thickness of the film and the thermal penetration depth, the thermal conductivity of thin films and interface thermal conductance can be subsequently obtained by fitting different frequency regions of one FDTR measurement curve. FDTR measurements are then conducted along with the aforementioned analysis to obtain the thermal conductivity of SiO2 thin films and interface thermal conductance SiO2 and Si. FDTR measurement results agree well with the TDTR measurements, but promises to be a much easier implementation than TDTR measurements.

scholarly journals High thermal conductive copper/diamond composites: state of the art

2020 ◽  
Vol 56 (3) ◽  
pp. 2241-2274
Author(s):  
S. Q. Jia ◽  
F. Yang
Keyword(s):  
Thermal Conductivity ◽  
Electronic Devices ◽  
Thermal Conductance ◽  
High Thermal Conductivity ◽  
Power Electronic ◽  
Practical Application ◽  
Boundary Area ◽  
Interface Characteristics ◽  
Composite Interface ◽  
Interface Thermal Conductance

Abstract Copper/diamond composites have drawn lots of attention in the last few decades, due to its potential high thermal conductivity and promising applications in high-power electronic devices. However, the bottlenecks for their practical application are high manufacturing/machining cost and uncontrollable thermal performance affected by the interface characteristics, and the interface thermal conductance mechanisms are still unclear. In this paper, we reviewed the recent research works carried out on this topic, and this primarily includes (1) evaluating the commonly acknowledged principles for acquiring high thermal conductivity of copper/diamond composites that are produced by different processing methods; (2) addressing the factors that influence the thermal conductivity of copper/diamond composites; and (3) elaborating the interface thermal conductance problem to increase the understanding of thermal transferring mechanisms in the boundary area and provide necessary guidance for future designing the composite interface structure. The links between the composite’s interface thermal conductance and thermal conductivity, which are built quantitatively via the developed models, were also reviewed in the last part.

Phonon Wave Heat Conduction in Thin Films and Superlattices

1999 ◽  
Vol 121 (4) ◽  
pp. 945-953 ◽  
Author(s):  
G. Chen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Ray Tracing ◽  
Thermal Conductance ◽  
Single Layer ◽  
Ray Tracing Method ◽  
Conductivity Of Thin Films ◽  
Tracing Method

Heat conduction in thin films and superlattices is important for many engineering applications such as thin-film based microelectronic, photonic, thermoelectric, and thermionic devices. Past modeling efforts on the thermal conductivity of thin films were based on solving the Boltzmann transport equation that treats phonons as particles. The effects of phonon interference and tunneling on the heat conduction and the thermal conductivity of thin films and superlattices remain to be explored. In this work, the wave effects on the heat conduction in thin films and superlattices are studied based on the consideration of the acoustic wave propagation in thin film structures and neglecting the internal scattering. A transfer matrix method is used to calculate the phonon transmission and heat conduction through these structures. The effects considered in this work include the phonon interference, tunneling, and confinement. The phonon dispersion is considered by introducing frequency-dependent Lamb constants. A ray-tracing method that treats phonons as particles is also developed for comparison. Sample calculations are performed on double heterojunction structures resembling Ge/Si/Ge and n-period superlattices similar to Ge/Si/n(Si/Ge)/Ge, It is found that phonon confinements caused by the phonon spectra mismatch and by the total internal reflection create a dramatic decrease of the overall thermal conductance of thin films. The phonon interference in a single layer does not have a strong effect on its thermal conductance but for superlattice structures, the stop bands created by the interference effects can further reduce the thermal conductance. Tunneling of phonon waves occurs when the constituent layers are 1–3 monolayer thick and causes a slight recovery in the thermal conductance when compared to thicker layers. The thermal conductance obtained from the ray tracing and the wave methods approaches the same results for a single layer. For superlattices, however, the wave method leads to a finite thermal conductance even for infinitely thick superlattices while the ray tracing method gives a thermal conductance that decreases with increasing number of layers. Implications of these results on explaining the recent thermal conductivity data of superlattices are explored.

Thermal Conductivity and Interface Thermal Conductance in Composites of Titanium With Graphene Platelets

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
H. Zheng ◽  
K. Jaganandham
Keyword(s):  
Thermal Conductivity ◽  
Physical Vapor Deposition ◽  
Composite Films ◽  
Thermal Conductance ◽  
Single Layer ◽  
Field Analysis ◽  
Titanium Matrix ◽  
Titanium Film ◽  
Graphene Platelets ◽  
Interface Thermal Conductance

Composite films of graphene platelets (GPs) in titanium matrix were prepared on silicon (001) substrates by physical vapor deposition of titanium using magnetron sputtering and dispersion of graphene platelets. The graphene platelets were dispersed six times after each deposition of titanium film to form the composite film. Samples of titanium film and titanium film with a single layer of dispersed graphene platelets were also prepared by the same procedure. The distribution of the graphene platelets in the film was analyzed by scanning electron microscopy. Energy dispersive spectrometry was used to infer the absence of interstitial elements. The thermal conductivity of the composite and the interface thermal conductance between titanium and silicon or titanium and graphene platelets was determined by three-omega and transient thermo reflectance (TTR) techniques, respectively. The results indicate that the thermal conductivity of the composite is isotropic and improved to 40 Wm−1K−1 from 21 Wm−1 K−1 for Ti. The interface thermal conductance between titanium and silicon is found to be 200 MWm−2K−1 and that between titanium and graphene platelets in the C-direction to be 22 MWm−2K−1. Modeling using acoustic and diffuse mismatch models was carried out to infer the magnitude of interface thermal conductance. The results indicate that the higher value of interface thermal conductance between graphene platelets in the ab plane and titanium matrix is responsible for the isotropic and improved thermal conductivity of the composite. Effective mean field analysis showed that the interface thermal conductance in the ab plane is high at 440 MWm−2K−1 when GPs consist of 8 atomic layers of graphene so that it is not a limitation to improve the thermal conductivity of the composites.

Thermal Conductivity Behaviour of Al/Diamond and Ag/Diamond Composites in the Temperature Range 4 K < T < 293 K

2015 ◽  
Vol 825-826 ◽  
pp. 197-204 ◽  
Author(s):  
Christian Edtmaier ◽  
Ernst Bauer ◽  
Zeze Serge Tako ◽  
Jakob Segl
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductance ◽  
Model Systems ◽  
Matrix Composition ◽  
Particle Sizes ◽  
Temperature Range ◽  
The Matrix ◽  
Conductivity Behaviour ◽  
Metal Layers ◽  
Interface Thermal Conductance

Two different systems, the non-reactive Ag–diamond and the reactive Al–diamond system, were assessed by their thermal conductivity behaviour, both were fabricated by gas pressure assisted infiltration of densely packed diamond bulks with aluminium or silver and different Si-concentration and diamonds of varying particle sizes. The effect of Si-concentration on the interface thermal conductance h between Al, Ag and diamonds was investigated in dependence of temperature by measuring thermal conductivity of composites with different sized diamond particles in the temperature range from 4 K up to ambient. Composite thermal conductivities κc(T) can be as high as 860 W m-1 K-1 at roughly 100 K for Al/diamond and 1100 W m-1 K-1 for Ag–Si/diamond at approx. 150 K. Although the Si concentration in the matrix plays an eminent role for κc(T), i.e. the lower the Si concentration, the higher κc(T), interface thermal conductance is almost unaffected in the reactive Al-diamond system. Furthermore, they are close to values determined on clean model systems, i.e. sputtered and evaporated metal layers on diamond monocrystals. For Ag–diamond composites, the matrix composition of Ag–1Si seems to reflect an optimal composition, as the highest thermal conductivity κc(T) and an extraordinary higher interface conductance was achieved compared to Ag–3Si/diamond composites.

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