Emissivity of liquid silicon in visible and infrared regions

Takasuka, Eiryo; Tokizaki, Eiji; Terashima, Kazutaka; Kimura, Shigeyuki

doi:10.1063/1.364418

Cited by 43 publications

(33 citation statements)

References 5 publications

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“…(2) was determined as a constant value which made the calculated temperature at the equator to be the same value as the measured one under the conditions that the specimen was levitated in vacuum without laser irradiation; (c) constant values Q 0 and Q 1 in Eq. (3) were determined to reproduce the temperature increase and oscillation during irradiation by the CO 2 laser in vacuum; (d) the coefficient of heat transfer h g0 was determined to reproduce the temperature decrease during irradiation by the CO 2 laser in gas flow; and (e) the experimental value of the thermal conductivity was determined by a linear interpolation method based on comparison of the phase delay ϕ obtained experimentally with the calculated one, where ε = 0.2 [23], C P = 26 J · mol −1 · K −1 at the melting point [6], and the density was substituted by the value determined in the present experiment. A cross-correlation function C C (t ) for the temperature T (t) and the reference signal for controlling the laser power f (t) ∝ Q 0 + Q 1 sin ω 0 t is as follows:…”

Section: Analysis Of Periodic Heating Methods For Specimenmentioning

confidence: 99%

“…On the other hand, large undercooling of the melt was achieved by the gas flow, but it was difficult to determine h g (θ ) precisely due to the complicated flow field of the gas between the RF coil and the melt. Takasuka et al [23] reported that the spectral emissivity of silicon melt at 1688 K for the range from 500 to 800 nm was almost 0.27 and the average spectral emissivity from 900 to 2600 nm was 0.21. They also showed that these emissivities had a very weak dependence on temperature from 1688 to 1823 K. Therefore, the present authors presumed that the total hemispherical emissivity was constant and has no temperature dependence even in the undercooled region.…”

Section: Thermal Conductivity Of Silicon Meltmentioning

confidence: 98%

“…The low emissivity of the silicon melt suggests a metal-like property of the melt. Takasuka et al [23] reported the dominant effect of free electrons on the optical properties of a melt. It is well-known that thermal and electrical conductivities of metals are proportional at a given temperature, but with a decrease in temperature the electrical conductivity increases while the thermal conductivity decreases.…”

Section: Thermal Conductivity Of Silicon Meltmentioning

confidence: 99%

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Density and Thermal Conductivity Measurements for Silicon Melt by Electromagnetic Levitation under a Static Magnetic Field

et al. 2007

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The density and thermal conductivity of a high-purity silicon melt were measured over a wide temperature range including the undercooled regime by non-contact techniques accompanied with electromagnetic levitation (EML) under a homogeneous and static magnetic field. The maximum undercooling of 320 K for silicon was controlled by the residual impurity in the specimen, not by the melt motion or by contamination of the material. The temperature dependence of the measured density showed a linear relation for temperature as:where T m is the melting point of silicon. A periodic heating method with a CO 2 laser was adopted for the thermal conductivity measurement of the silicon melt. The measured thermal conductivity of the melt agreed roughly with values estimated by a Wiedemann-Franz law.

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Section: Analysis Of Periodic Heating Methods For Specimenmentioning

confidence: 99%

Section: Thermal Conductivity Of Silicon Meltmentioning

confidence: 98%

Section: Thermal Conductivity Of Silicon Meltmentioning

confidence: 99%

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Density and Thermal Conductivity Measurements for Silicon Melt by Electromagnetic Levitation under a Static Magnetic Field

et al. 2007

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“…Most previous attempts have focused mainly on pure metals and semiconductors such as copper, [4][5][6][7][8][9][10][11] Ag, [4,5,[10][11][12] Au, [5,6,10,11,13] nickel, [5,7,14] Co, [5,7,14] Fe, [5,7,14,15] Ge, [17,18,19] Si, [16,17,[19][20][21][22][23] etc. Furthermore, radiation mechanisms of these pure materials have been discussed from the wavelength dependence of the emissivities, which is a reflection of the electronic structure (density of states (DOS) of electrons) for the metals at high temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature and compositional dependencies of normal spectral emissivities at 632.8 nm for solid Cu-Ni alloys—Ellipsometric measurements and formulation of empirical prediction equation

Tanaka

Sato

Susa

2005

Metall Mater Trans A

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Normal spectral emissivities of solid Cu-Ni alloys were determined using an ellipsometer combined with an electric furnace for a wavelength of 632.8 nm in the temperature ranges between 800 K and the respective solidus temperatures. The emissivities of the alloys had slightly positive temperature coefficients and seemed to be on quadratic functions of the atomic fraction of nickel. Thermal radiation of transition metals in the visible and near-infrared regions is generally considered to stem from the excitation-relaxation processes of free electrons and inner shell electrons, i.e., electrons at the d-like levels in the Cu-Ni system. Thus, the contribution from the former to the emissivities has been calculated on the basis of the free-electron model with damping. The difference between measured and calculated values corresponds to the contribution from inner shell electrons, which has been found to depend strongly upon neither temperature nor chemical composition in the range of the nickel atomic fraction, X Ni Ͼ 0.2. On the basis of these findings, an empirical prediction equation for the emissivity at 632.8 nm for solid Cu-Ni alloys has been proposed: this equation applies at temperatures higher than 800 K in the range of X Ni Ͼ 0.2 and can predict emissivity with an uncertainty less than 13 pct.

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“…12 Normal spectral emissivity of molten silicon at the melting point[39][40][41][42][43][44][45][46][47][48][49][50].…”

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confidence: 99%

Thermophysical Properties of Molten Silicon

Hibiya

Fukuyama

Tsukada

et al. 2008

Crystal Growth Technology

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IntroductionModern society features information processing on a large scale and is supported by information technologies, which require high-speed data processing and high-speed data transmission. From the viewpoint of materials science and engineering, this is supported by high-quality semiconductor crystals, produced from high-temperature melt processes, such as the Czochralski, the floating zone, Bridgman processes, and so on. In order to understand and control these high-temperature processes, computer modeling is one of the superior tools available. This shows us the physics of these processes and how to improve processes and products, as shown in Fig. 4.1 [1]. This has been made possible thanks to the year-by-year improvements in computer performance, and even turbulence flow can now be handled. In modeling equations for continuity, momentum, energy and the Maxwell equation are solved simultaneously. In order to calculate temperature, flow and pressure fields of a high-temperature process, the thermophysical properties of the molten state in particular are indispensable. A survey was carried out on the required thermophysical properties for silicon crystal growth processes and on thermophysical properties actually employed in modeling in Japan: see Fig. 4.2 and Table 4.1 [2][3][4]. Table 4.1 shows thermophysical properties employed in 44 papers. The scatter of the data is rather large; particularly for the temperature coefficient of surface tension, the difference is one order of magnitude. Historically, Glazov et al. [5] reviewed thermophysical properties of molten semiconductors not only for molten silicon but also for other compound molten semiconductors. However, modern society requires the development of new measurement techniques and improvements in the accuracy and precision of data. Iida and Guthrie [6] overviewed thermophysical properties of molten metals and methods for measurements; this is a good textbook for thermophysical property measurement of high-temperature melts. Figure 4.2 shows that thermal conductivity, specific heat capacity and surface tension are urgently required. Although thermal conductivity is required to calculate heat balance at the solid/liquid interface during crystal growth and is important to Crystal Growth Technology. Edited by Hans J. Scheel and Peter Capper

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Emissivity of liquid silicon in visible and infrared regions

Cited by 43 publications

References 5 publications

Density and Thermal Conductivity Measurements for Silicon Melt by Electromagnetic Levitation under a Static Magnetic Field

Density and Thermal Conductivity Measurements for Silicon Melt by Electromagnetic Levitation under a Static Magnetic Field

Temperature and compositional dependencies of normal spectral emissivities at 632.8 nm for solid Cu-Ni alloys—Ellipsometric measurements and formulation of empirical prediction equation

Thermophysical Properties of Molten Silicon

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