Thermal conductivity of silicon

C.J. Glassbrenner and G.A. Slack. Thermal Conductivity of Silicon and Germanimn from 3 °K to the Melting Point Physical Review A 134 (1963), 1058-1069. 

High Temperature. The low coefficient of thermal expansion and high thermal conductivity of silicon carbide bestow it with excellent thermal shock resistance. Combined with its outstanding corrosion resistance, it is used in heat-transfer components such as recuperator tubes, and furnace components such as thermocouple protection tubes, cmcibles, and burner components. Silicon carbide is being used for prototype automotive gas turbine engine components such as transition ducts, combustor baffles, and pilot combustor support (145). It is also being used in the fabrication of rotors, vanes, vortex, and combustor. 

If silicon technology is involved all thermal sensors suffer from the high thermal conductivity of silicon, which dramatically decrease their sensitivity [12]. However, by use of micromachining and integrated silicon technology a powerful thermal biosensor can be realized. Using a thermopile integrated on a thin micromachined silicon membrane reduces thermal loss due to the substrate and so excellent performance can be accomplished [13]. 

In this section, we compare BTE and MD predictions of bulk thermal conductivity of silicon to the available experimental data [74] over a temperature range of 500K to lOOOK (Fig. 4). The BTE predictions are obtained from the full phonon dispersion model described in section 2.3. This full phonon dispersion model involves an adjustable parameter, the Gruneisen constant (y), which is set... 

We next present the BTE and MD predictions of thermal conductivities of silicon thin films. The thermal properties of silicon thin films are of paramount importance to the transistor industry. Silicon-on-insulator (SOI) and strained silicon transistors are composed of silicon thin films. In both cases, the thin silicon film is deposited on top of poor thermally conducting materials, and the thermal energy generated by the Joule effect has to be removed along the silicon film plane. A thorough understanding of the thermal properties of thin silicon films is essential for the accurate prediction of the thermal response of these transistors. The dimensions of the silicon thin film in... 

SOI and strained silicon transistors are comparable to or smaller than the phonon s mean free path (which, for silicon, has been estimated as 300 nm at 300K) [53], In this limit, the film surfaces alter the phonon dispersion relations [76], and the phonon-surface scattering may become the predominant scattering mechanism [3, 53], Since phonons are the main carriers of thermal energy in silicon, these effects alter the thermal conductivity, which differs from that of bulk silicon [10, 36, 77], Measurements of the thermal conductivities of silicon films of thicknesses down to 74 nm found a reduction of 50% with respect to the bulk value at 300K [53], This reduction depends on the temperature and the thickness of the film [3, 53],... 

Volz, S.G. and G. Chen, Molecular Dynamics Simulation of Thermal Conductivity of Silicon Nanowires. Applied Physics Letters, 1999. 75(14) p. 2056-2058. 

Materials of which compositions are isotopically controlled are expected to show improved physical and nuclear properties which can not be attained by usual combinations of elements[l]. Natural silicon is composed of three stable isotopes such as 2 Si, "Si and "Si. If the purified Si is obtained, high thermal conductivity of silicon and its compounds is achievable because of suppressing isotope scattering against phonon conduction. 

Y.W. Lee, et al., Study on the mechanical properties and thermal conductivity of silicon carbide-, zirconia- and magnesia aluminate-based simulated inert matrix nuclear fuel materials after cyclic thermal shock../. Nucl. Mater. 319, 15-23 (2003). 

Briefly, three points of porous SiC-based catalytic support properties can be emphasized (i) SiC shows very good mechanical properties which gives resistance to erosion and attrition, in addition to a high thermal stability (ii) SiC has a higher thermal conductivity compared with the more conventional supports which could prevent the metal sintering (iii) SiC is particularly inactive with respect to chemical reagents such as acids or bases. Therefore, the active phase can be easily reprocessed after simple acidic or basic treatments. Among refractory materials, the thermal conductivity of silicon carbide, SiC (500 W m-1K-1 for crystalline state, at room temperature) is close to that of metals such as Ag or Cu (400-500 Wm K-1). 

What is the thermal conductivity of silicon nanowires, n-alkane single molecules, carbon nanotubes, or thin films How does the conductivity depend on the nanowiie dimension, nanotube chirality, molecular length and temperature, or the film thickness and disorder More profoundly, what are the mechanisms of heat transfer at the nanoscale, in constrictions, at low tanperatures Recent experiments and theoretical studies have dononstrated that the thermal conductivity of nanolevel systems significantly differ from their macroscale analogs [1]. In macroscopic-continuum objects, heat flows diffusively, obeying the Fourier s law (1808) of heat conduction, J = -KVT, J is the current, K is the thermal conductivity and VT is the temperature gradient across the structure. It is however obvious that at small scales, when the phonon mean free path is of the order of the device dimension, distinct transport mechanisms dominate the dynamics. In this context, one would like to understand the violation of the Fourier s... 

N. Hirosaki, Y. Okamoto, M. Ando, F. Munakata and Y. Akimune, Effect of Grain Growth on the Thermal Conductivity of Silicon Nitride , Journal of the Ceramic Society of Japan, 104, 1996, 50 54. 

Specific Heat. The specific heat (C ) of the covalent carbides as a function of temperature is shown in Fig. 8.1 On a weight basis (J/g K), the specific heat of silicon carbide and particularly boron carbide is higher than that of the other refractory carbides and nitrides listed in Table 8.2 Thermal Conductivity. The thermal conductivity or k (i.e., the time rate of transfer of heat by conduction) of covalent carbides, unlike that of the interstitial carbides, decreases with increasing temperature as shown in Fig. 8.2.P It is highly dependent on the method of formation which is reflected by the large spread in values. The thermal conductivity of silicon carbide... 

This data is representative but not authoritative. Various sources quote difference values. The thermal conductivity of silicon carbide varies greatly with temperature. An approximate allowance was made for this by taking the high figure at low mean interface temperatures and vice versa. 

Finally, Myers Danner (1993) have developed equations to estimate liquid thermal conductivities of silicon compounds. Another i proach to estimating liquid thermal... 

K. Nagata 2002, Thermal conductivities of silicon and germanium in solid and liquid states measured by non-stationary hot wire method with silica coated probe , J. Cryst. Growth 234, 121-131. 

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