Thermal conductivity of yttria-stabilized zirconia–hafnia solid solutions

Winter, Michael; Clarke, David R.

doi:10.1016/j.actamat.2006.06.038

Cited by 135 publications

(70 citation statements)

References 25 publications

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“…Investigations of bulk ceramic or sputter deposited thin film poly-crystalline hafnia doped/stabilized with yttria for thermal barrier coating applications have reported relatively low thermal conductivities of 1.5-2.0 W/mK. 322,323 Slightly higher values of 1.2-2.5 W/mK have been reported for pure nanocrystalline sputter deposited HfO 2 films. 323,324 However, substantially reduced values of 0.5-1.7 W/mK have been reported for ALD HfO 2 gate oxide films which exhibit a mixed amorphous/nano-crystalline microstructure.…”

Section: 283mentioning

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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Section: 283mentioning

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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“…We assume that the substitutional Hf 4+ ions do not influence the ionic conductivity since no additional oxygen vacancies are introduced within the lattice. The substituted Hf 4+ ions will, however, have a higher energy than Zr 4+ within the lattice, since Hf 4+ is twice as heavy as Zr 4+ , thereby creating mass distortion of the lattice [26]. This increased energy may result in segregation of the Hf atoms to the grain boundaries in case of high-energy ion bombardment during growth.…”

Section: Ionic Conductivitymentioning

confidence: 99%

Effects of dopant concentration and impurities on the conductivity of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

Sillassen¹,

Eklund²,

Pryds³

et al. 2010

Solid State Ionics

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Cubic yttria-stabilized zirconia (YSZ) films with yttria concentrations of 8.7, 9.9, and 11 mol% have been deposited by reactive pulsed DC magnetron from Zr-Y alloy targets. The overall microstructure and texture in the films showed no dependence on the yttria -concentration. Films deposited at floating potential had a <111> texture. Single -line profile analysis of the 111 X-ray diffraction peak yielded a grain size of ~18 nm and a microstrain of ~2%, regardless of deposition temperature. Films deposited at 400 ºC and selected bias voltages in the range from -70 V to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of ~ 7 nm and a microstrain of ~2.5% at a bias voltage of -200 V with additional incorporation of argon.Furthermore, the effect of impurities on the ionic conductivity has been investigated, since Hf impurities were found in the samples with yttria concentrations of 8.7, and 9.9 mol%. Temperaturedependent impedance spectroscopy of the YSZ films, deposited at 400 ºC and floating potential, showed no variation of the in-plane ionic conductivity with yttria concentration. However, for films 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 deposited at 400 ºC and a bias -70 V, the in-plane ionic conductivity decreased systematically for samples with yttria concentrations of 8.7 and 9.9 mol% compared to the sample with 11 mol% yttria. This suggests that ionic conduction is not a purely bulk mechanism, but mainly related to the grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.25 and 1.32 eV. Manuscript Click here to view linked References

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“…The low thermal conductivity of yttria-stabilized zirconia (YSZ) is usually attributed to the high concentration of oxygen vacancies in this material [2][3][4]. Oxygen vacancies are very effective in scattering phonons, especially at high concentrations (typically 1.9 at.%) in the 8YSZ (7.6 m/o YO 1.5 ) composition currently used in the majority of thermal barrier coatings.…”

Section: Introductionmentioning

confidence: 99%

Low thermal conductivity without oxygen vacancies in equimolar YO1.5+TaO2.5- and YbO1.5+TaO2.5-stabilized tetragonal zirconia ceramics

et al. 2010

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Thermal conductivity of yttria-stabilized zirconia–hafnia solid solutions

Cited by 135 publications

References 25 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

Effects of dopant concentration and impurities on the conductivity of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

Low thermal conductivity without oxygen vacancies in equimolar YO1.5+TaO2.5- and YbO1.5+TaO2.5-stabilized tetragonal zirconia ceramics

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