Measuring the Thermal Conductivity of Porous, Transparent SiO2 Films With Time Domain Thermoreflectance

Hopkins, Patrick E.; Kaehr, Bryan; Phinney, Leslie M.; Koehler, Timothy; Grillet, Anne; Dunphy, Darren R.; Garcia, Fred L.; Brinker, C. Jeffrey

doi:10.1115/1.4003548

Cited by 51 publications

(56 citation statements)

References 37 publications

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“…In order to determine the cross-plane thermal conductivity and interfacial thermal resistance, the temperature-dependent change in reflectivity was modeled using previously described methods. 147,148 This simulation requires both the Al film thickness and heat capacity of the high-k dielectric. The former was determined via both mechanical profilometry as well as picosecond acoustics, the details of which have been described thoroughly elsewhere.…”

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confidence: 99%

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

ECS J. Solid State Sci. Technol.

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Atomic layer deposited (ALD) high-dielectric-constant (high-k) materials have found extensive applications in a variety of electronic, optical, optoelectronic, and photovoltaic devices. While electrical, optical, and interfacial properties have been the primary consideration for such devices, thermal and mechanical properties are becoming an additional key consideration for many new and emerging applications of ALD high-k materials in electromechanical, energy storage, and organic light emitting diode devices. Unfortunately, a clear correspondence between thermal/mechanical and electrical/optical properties in ALD high-k materials has yet to be established, and a detailed comparison to conventional silicon-based dielectrics to facilitate optimal material selection is also lacking. In this regard, we have conducted a comprehensive investigation and review of the thermal, mechanical, electrical, optical, and structural properties for a series of prevalent and emerging ALD high-k materials including aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), hafnium oxide (HfO 2 ), and beryllium oxide (BeO). For comparison, more established silicon-based dielectrics were also examined, including thermally grown silicon dioxide (SiO 2 ) and plasma-enhanced chemically vapor deposited hydrogenated silicon nitride (SiN:H). We find that in addition to exhibiting high values of dielectric permittivity and electrical resistance that exceed those of SiO 2 and SiN:H, the ALD high-k materials exhibit equally exceptional thermal and mechanical properties with coefficients of thermal expansion ≤ 6 × 10 -6 / • C, thermal conductivites (κ) of 3-15 W/m K, and Young's modulus and hardness values exceeding 200 and 25 GPa, respectively. In many cases, the observed extreme thermal/mechanical properties correlate with the presence of crystallinity in the ALD high-k films. In contrast, some of the electrical and optical properties correlate more strongly with the percentage of ionic vs. covalent bonds present in the high-k film. Overall, the ALD high-k dielectrics investigated concurrently exhibit compelling thermal/mechanical and electrical/optical properties. The drive to reduce gate leakage currents in highly scaled complementary metal-oxide-semiconductor (CMOS) transistors has led to the exploration and development of a wide variety of high-dielectricconstant (high-k) materials to replace silicon dioxide (SiO 2 ) as the insulating gate dielectric material.1-8 Many of these same high-k materials have found additional applications in future non-CMOS logic and memory storage products such as solid-state electrolytes in resistive switching devices, 9,10 tunnel barriers in spin-transport devices, 11 and as a ferroelectric in magnetoelectric devices. While electrical, physical, and thermodynamic properties have clearly been a key consideration in all of the above applications, thermal properties have become an additional important consideration for higk-k dielectrics as aggressive dimensional scaling of devices has created the need to dissipate ...

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Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

ECS J. Solid State Sci. Technol.

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“…We measured the thermal conductivity of the thin films of convectively assembled TiO 2 nanoparticles with TDTR 26,44,119 in a "probe through the glass" geometry that we discuss elsewhere. 123 We note that this geometry requires different thermal modeling than discussed in Section 3, as we discuss in detail in Ref. 123.…”

Section: 133106 (2011))mentioning

confidence: 99%

“…123 We note that this geometry requires different thermal modeling than discussed in Section 3, as we discuss in detail in Ref. 123. The room temperature thermal conductivities of the eight different films as a function of order parameter are shown in Fig. 14.…”

Section: 133106 (2011))mentioning

confidence: 99%

“…Figure 18 shows sample TDTR data of the aerogel films along with data from the sample with no film (i.e., air) and data from a previously examined mesoporous silica film (``EISA''). 123 Along with the data, we show the predictions from the thermal model for various reductions in SiO 2 sample κ. Since the pump is modulated at 11 MHz, the TDTR data represent measurements of the thermal effusivity of the porous SiO 2 sample, κ C E = .…”

Section: Minimum Thermal Conductivity Considerations In Aerogel Thinmentioning

confidence: 99%

“…Due to the low thermal conductivity of the aerogel samples, the TDTR signal is relatively insensitive to the Al/sample thermal boundary conductance. 123,142 The presence of any thermal mass on the free surface of the Al increases the TDTR signal. In fact, TDTR has the sensitivity to be able to measure thermal conductivities of samples with thermal effusivities in the solid matrix of the porous sample as low as 10% of bulk SiO 2 , representing a reduction in thermal conductivity to 1% of bulk.…”

Section: Minimum Thermal Conductivity Considerations In Aerogel Thinmentioning

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Interfacial electron and phonon scattering processes in high-powered nanoscale applications.

Hopkins¹

2011

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The overarching goal of this Truman LDRD project was to explore mechanisms of thermal transport at interfaces of nanomaterials, specifically linking the thermal conductivity and thermal boundary conductance to the structures and geometries of interfaces and boundaries. Deposition, fabrication, and post possessing procedures of nanocomposites and devices can give rise to interatomic mixing around interfaces of materials leading to stresses and imperfections that could affect heat transfer. An understanding of the physics of energy carrier scattering processes and their response to interfacial disorder will elucidate the potentials of applying these novel materials to next-generation high powered nanodevices and energy conversion applications. An additional goal of this project was to use the knowledge gained from linking interfacial structure to thermal transport in order to develop avenues to control, or "tune" the thermal transport in nanosystems.4

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Determination of Structural Parameters of Thin-Film Photocatalytic Materials by BDS

Korte

Franko

2015

Int J Thermophys

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A method for determination of structural parameters of some thin-film photocatalytic materials is presented. The analysis was based on the material's thermal parameter dependences on its surface structure or porosity and was thus performed by the use of beam deflection spectroscopy (BDS) supported by theoretical analysis made in the framework of complex geometrical optics. The results obtained by BDS were than compared with those received on the basis of AFM and SEM measurements and found to be in good agreement.

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Measuring the Thermal Conductivity of Porous, Transparent SiO2 Films With Time Domain Thermoreflectance

Cited by 51 publications

References 37 publications

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Interfacial electron and phonon scattering processes in high-powered nanoscale applications.

Determination of Structural Parameters of Thin-Film Photocatalytic Materials by BDS

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