Size effects on the thermal conductivity of amorphous silicon thin films

Braun, Jeffrey L.; Baker, Christopher H.; Giri, Ashutosh; Elahi, Mirza Mohammad Mahbube; Artyushkova, Kateryna; Beechem, Thomas E.; Norris, Pamela M.; Leseman, Zayd Chad; Gaskins, John T.; Hopkins, Patrick E.

doi:10.1103/physrevb.93.140201

Cited by 122 publications

(110 citation statements)

References 41 publications

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“…The existence of long wavelength heat carriers has recently been experimentally observed in amorphous silicon films and suggests the nature of energy transport in amorphous films may not be as simple as is often assumed. 315 As the value of 1 W/mK reported by Jacquot for nano-crystalline AlN indicates, 309 the thermal conductivity of AlN may also be a strong function of crystallinity/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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“…This is in contrast to our recent experimental results (from Ref. [212], which is also included in Fig. 5.6) demonstrating size effects on the thermal conductivity of amorphous Si thin films, where a significant portion of heat flow is due to propagons (that represent delocalized propagating modes).…”

Section: Sensitivity To Ratiocontrasting

confidence: 99%

“…Also included are the measured thermal conductivities of amorphous Si from Ref. [212], which shows considerable size effects due to the contribution from propagating modes to the thermal conductivity.…”

Section: Thermal Boundary Resistance and Thermal Conductivity Of Amormentioning

confidence: 99%

The Role of Electronic and Vibrational Scattering on Thermal Transport Across Multiple Interfaces in Nanostructures

Giri¹

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Rapid miniaturization and faster working speeds in electronic devices has led to challenges in their thermal mitigation. However, thermal conductivity of the constituent materials in the nano-devices, even though a very critical parameter in their design, is mostly overlooked and the thermal performance of the device is mainly controlled through packaging techniques. However, it would be advantageous for a diverse spectrum of technologies, which ultimately fail due to either high density of interfaces or due to high operating frequencies, to control and tune thermal properties at the submicron length scale and femtoto-picosecond time scales. Therefore, a comprehensive understanding of how heat flows across nanosystems that are mostly limited by interfacial thermal transport would prove to be quintessential for the design of various electronic devices. For example, the contribution of electronic thermal resistance across metal/semiconductor interfaces has been a subject of debate for the past several decades; understanding the intrinsic electron-electron, electron-phonon and electron-boundary scattering mechanisms in these devices could potentially lead to transistors with higher operating frequencies. Moreover, with the advent of new fabrication technologies, the role of phononic-driven thermal resistances across hybrid interfaces of inorganic/organic materials and amorphous semiconductor superlattices (SLs) with high density of interfaces has largely been unexplored.It is the goal of this work to comprehensively explore interfacial thermal transport in these material systems by understanding the fundamental scattering mechanisms of the energy carriers, which dominate thermal transport at various length and time scales. In this regard, a combination of time-domain thermoreflectance (TDTR) experiments and non-equilibrium molecular dynamics (NEMD) simulations will be implemented to achieve these goals.The nonequilibrium between electrons and phonons at metal/semiconductor interfaces in high frequency microelectronic devices serves as a bottleneck to heat transfer in these ii devices. To understand this phenomena, TDTR is used to probe the highly non-equilibrium condition that is induced due to pulse absorption by thin Au films deposited on various dielectric substrates. For electron temperature excursions of ≤ 3,500 K in Au, it is shown that while the increase in the excited carrier density increases the e-p coupling in the metal, the bond strength between the metal and the substrate dictates the energy transfer rate across the interface during this highly non-equilibrium time regime. Furthermore, at time scales when the electrons have fully thermalized with the lattice, electron-phonon coupling does not influence the phonon-driven thermal boundary conductance.Another phenomena that lead to device failure are the phonon-driven thermal boundary resistance in multilayered semiconductors used in technologies such as thermoelectric power generation or phase change memory devices. TDTR is used to simultaneously...

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“…Braun et al provided a systematic study on the thickness‐dependent thermal conductivity of a‐Si nanoscale films ranging from 3 to 1636 nm in thickness using the TDTR method . The experimentally observed thermal conductivity was size independent and constant when the thickness was less than ≈100 nm and then rapidly increased with thickness in the range of 100 to 2000 nm.…”

Section: Thermal Conductivity Of Amorphous Nanomaterialsmentioning

confidence: 99%

Thermal Conductivity of Amorphous Materials

Zhou

Cheng

Chen

et al. 2019

Adv Funct Materials

194

110

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Thermal conductivity is one of the most fundamental properties of solid materials. The thermal conductivity of ideal crystal materials has been widely studied over the past hundreds years. On the contrary, for amorphous materials that have valuable applications in flexible electronics, wearable electrics, artificial intelligence chips, thermal protection, advanced detectors, thermoelectrics, and other fields, their thermal properties are relatively rarely reported. Moreover, recent research indicates that the thermal conductivity of amorphous materials is quite different from that of ideal crystal materials. In this article, the authors systematically review the fundamental physical aspects of thermal conductivity in amorphous materials. They discuss the method to distinguish the different heat carriers (propagons, diffusons, and locons) and the relative contribution from them to thermal conductivity. In addition, various influencing factors, such as size, temperature, and interfaces, are addressed, and a series of interesting anomalies are presented. Finally, the authors discuss a number of open problems on thermal conductivity of amorphous materials and a brief summary is provided.

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Size effects on the thermal conductivity of amorphous silicon thin films

Cited by 122 publications

References 41 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

The Role of Electronic and Vibrational Scattering on Thermal Transport Across Multiple Interfaces in Nanostructures

Thermal Conductivity of Amorphous Materials

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