Surface Tension Variation of Molten Silicon Measured by Ring Tensiometry Technique and Related Temperature and Impurity Dependence

The surface tension of non doped, gallium-doped and boron-doped silicon melts has been measured as a function of temperature in purified argon atmosphere (oxygen partial pressure was less than 10 -8 MPa) using the ring tensiometry technique. In all cases, the surface tension decreases linearly with increasing temperature. The surface tensions of γ={763-0.219×( T - T m )}×10 -3 N/m in the non doped silicon melt, γ={777-0.243×( T - T m )}×10 -3 N/m in the gallium-doped silicon melt and γ={721-0.098×( T - T m )}×10 -3 N/m in the boron-doped silicon melt were obtained. We have found that the surface tension of the silicon melt depends on the species of impurity. However, the surface tension anomaly near the solidification point previously reported by Sasaki et al. [1] was not observed under any experimental conditions.