Surface tension of liquid silicon: High or low value?

Sixty years after the first measurement of capillary properties of silicon, experimental results on the surface tension and temperature coefficient of liquid silicon are still divergent. The reason for this persisting divergence is discussed by examining the effect on these quantities of (i) oxygen contained as an impurity in the gas, (ii) impurities in Si and (iii) contamination by the supporting material (substrate or crucible). From the analysis of experimental data, the following expression is derived for the temperature dependence of the surface tension σ: σ(mN/m)=840(±45)−0.19(±0.09)(T(K)−1685).

► Surface condition of silicon as a function of partial pressure of oxygen in the furnace. ► Effects on silicon surface tension of contamination by the substrate. ► Recommended expression for the temperature dependence of the surface tension of pure Si.