This study examined the effect of natural convection in the modified laser flash method for the measurement of thermo physical properties of semiconductor melts. Common laser flash method uses a laser pulse to heat the front surface of a thin circular sample and measures the temperature transient of the rear surface. Thermal diffusivity is calculated based on the analysis of the transient heat conduction process. For semiconductor melts, the sample is contained in a specially designed quartz cell with optical windows. When the laser pulse heats the melt front surface, the resulting natural convection can introduce errors in the calculation of thermal diffusivity based on the heat conduction model. The effect of natural convection was evaluated by Computational Fluid Dynamics (CFD) simulations in this study. The results indicated that natural convection can decrease the time needed for the rear surface to reach its peak temperature, and can also decrease the peak temperature slightly. Based on our experimental data for Tellurium, the calculation using only heat conduction model resulted in a thermal diffusivity about 3% greater than that using the heat transfer model with natural convection.

Volume Subject Area:
Heat Transfer
Keywords:
Laser flash, heat conduction, natural convection, thermal property, semiconductor melt
Topics:
Convection, Heat conduction, Lasers, Natural convection, Semiconductors (Materials), Thermal properties
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Copyright © 2003
 by ASME
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