Updated Model for Thermal Conductivity Calculation of Thin Films of Silicon and Germanium

Баринов, А. А.; Liu, B.; Khvesyuk, V. I.; Zhang, K.

doi:10.1134/s1063778820100038

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…Fan et al used ab initio combined with the BTE to derive the lattice thermal transportation of monolayer Boron-based compounds: h-BX (X = N, P, As, Sb) [12]. Meanwhile, the thermal properties of other nanofilms (including: silicon, germanium, bismuth telluride, phosphorene and etc) were also calculated [13][14][15][16][17][18]. However, previous works focused on binary nitride (GaN, BN or AlN) nanofilms, but few theoretical studies on ternary AlGaN nanofilms were reported.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity and phonon scattering of AlGaN nanofilms by elastic theory and Boltzmann transport equation

Huang¹,

Fan²,

Sang³

et al. 2022

Semicond. Sci. Technol.

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Aluminum Gallium nitride (AlGaN) plays an essential role in deep ultra-violet light emitting diode, high electron mobility transistor and etc. For example, 2 nm to 5 nm AlGaN nanofilms consist of the quantum wells in ultra-violet light emitting diodes, which are attracting extensive attention during nowadays COVID 2019. Since most photons and heat are generated in these AlGaN nanofilms, thermal properties of AlGaN nanofilms strongly influenced heat dissipation of devices. In this paper, utilizing elastic theory and Boltzmann transport equation (BTE), the phonon dispersion relations, density of states, specific heat capacities and thermal conductivities of 2 nm AlδGa1-δN nanofilms with various δ are theoretically calculated at different temperatures. The thermal conductivity of nanofilm is significantly smaller than that of bulk counterpart. In contrast with the bulk AlGaN, due to the dominance of boundary scattering and alloy disorder scattering, the thermal conductivity of AlδGa1-δN exhibits similar dependence on Al concentration with bulk AlδGa1-δN. Meanwhile, since the screening of Umklapp scattering, the saturation temperature of thermal conductivity is delayed from 50-100 K of bulks to about 300 K of nanofilms. The shrinkage of nanofilms’ thermal conductivity is also slower than the bulks. We believe that our work will be helpful in controlling the self-heating effect of devices based on AlGaN nanofilms.

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Section: Introductionmentioning

confidence: 99%

Thermal conductivity and phonon scattering of AlGaN nanofilms by elastic theory and Boltzmann transport equation

Huang¹,

Fan²,

Sang³

et al. 2022

Semicond. Sci. Technol.

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“…The above method does not allow predicting the thermal properties of such structures, since the specular reflection parameter is used as a fitting parameter to ensure better agreement between theory and experiment [19,20]. However, it is worth noting that in [21,22], it is proposed to evaluate the parameter p as an integral (average) parameter for the sample.…”

Section: Effective Thermal Conductivity (Films and Tubes In-plane)mentioning

confidence: 99%

“…Therefore, a number of properties of the carrier medium (crystal lattice) are required to describe phonons: dispersion relations and the density of states (DOS). In this paper, we use a wellproven approach to the application of polynomial approximation of experimental data [19]. The result is a nonlinear dispersion relation that characterizes the elastic properties of a real medium.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…is the density of state [19]; , g j v is the phonon group velocity;  is the angle between the direction of incidence of a phonon and the normal to the surface; 1 2, j   is the coefficient of energy transfer from material 1 to material 2, and j l is the mean free path of phonons. Note that expression (2) is given in a quasi-isotropic approximation [19]; in this case, the heat flux propagates in the film (tube) or in the socalled in-plane direction. Thus, when calculating thermophysical properties, roughness is taken into account through the transfer coefficient 1 2, j   in expression (1) and through the mean free path j l in equation ( 2).…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Details of the calculation of b l can be found in the original work [18] or in our previous analysis [19]. After that, the average MFPs , b eff l are used to determine the effective longitudinal thermal conductivity of films (heat transfer rate) as a function of the size of the sample, its roughness, and temperature.…”

mentioning

confidence: 99%

See 2 more Smart Citations

A new technique for modelling phonon scattering processes at rough interfaces and free boundaries of solids

Баринов

Liu

Khvesyuk

2022

J. Phys.: Conf. Ser.

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Scattering processes at interfaces and free boundaries of solids strongly affect heat transfer in micro- and nanostructures such as integrated circuits, periodic nanostructures, multilayer thin films, and other nanomaterials. Among many influencing factors, surface roughness due to atomic disorder plays a significant role in the rate of thermal transport. Existing approaches have been developed only for the limiting cases of smooth or completely diffuse surfaces. We have developed a new effective and simple method based on a direct consideration of the scattering of elastic waves from a statistically random profile (using a normal Gaussian surface as an example). This approach, first, allows to generalize common methods for determining the thermal properties of a real random rough surface using simple modifications, and, second, provides a tool for calculating the Kapitza conductance and the effective longitudinal thermal conductivity and studying the influence of roughness on heat transfer.

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Generalized model of Kapitza conductance across rough interfaces

Khvesyuk

Liu

Баринов

2021

J. Phys.: Conf. Ser.

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This paper is devoted to the theoretical prediction of the interfacial heat transfer in nanostructured materials. The main task of this work is the analysis of interaction of elastic waves with the rough interface between two different solids. The presence of toughness leads to a significant increase in the resistance to heat transfer in nanostructures. This fundamental problem is discussed in relation to the commonly used method of wave scattering at rough surface: the Kirchhoff tangent plane method. The method assumes that at the point of the rough surface profile, the surface is regarded as locally smooth, and the reflection and transmission of the incident wave can be described by the scattering at the tangent plane of this point. Based on the elastic wave theory, we use the frequency-dependent continuity conditions to calculate the energy transmission coefficient at the interface. And then its effective value at the rough interface is estimated by using the Kirchhoff method. By substituting this effective value into the formula of Kapitza conductance, we can calculate the Kapitza conductance at the rough interface and analyze the effect of roughness on the interfacial heat transfer.

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Updated Model for Thermal Conductivity Calculation of Thin Films of Silicon and Germanium

Cited by 7 publications

References 25 publications

Thermal conductivity and phonon scattering of AlGaN nanofilms by elastic theory and Boltzmann transport equation

Thermal conductivity and phonon scattering of AlGaN nanofilms by elastic theory and Boltzmann transport equation

A new technique for modelling phonon scattering processes at rough interfaces and free boundaries of solids

Generalized model of Kapitza conductance across rough interfaces

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