Self-diffusivity of liquid silicon measured by pulsed laser melting

Abstract

The silicon liquid self-diffusivity was determined by pulsed laser melting of ${}^{\mathrm{30}}\mathrm{Si}$ ion implanted silicon-on-insulator thin films. Secondary ion mass spectrometry was employed to measure the ${}^{\mathrm{30}}{\mathrm{Si}}^{\mathrm{+}}$ concentration-depth profile before and after melting and solidification. Melt depth versus time and total melt duration were monitored by time-resolved lateral electrical conductance and optical reflectance measurements. One-dimensional diffusion simulations were utilized to match the final ${}^{\mathrm{30}}{\mathrm{Si}}^{\mathrm{+}}$ experimental concentration spatial profile given the initial concentration profile and the temporal melt-depth profile. The silicon liquid self-diffusivity at the melting point is ${\text{(4.0±0.5)×10}}^{\text{−4}} {\mathrm{cm}}^{\mathrm{2}}\mathrm{/s}.$ Calculations of buoyancy and Marangoni convection indicate that convective contamination is unlikely.