ABSTRACTThe frequency of the phonon line in the Raman scattering spectrum recorded during CW laser-beam heating of Si was used as a characteristic of the lattice temperature inside the laser spot. It is shown that Raman scattering is a good temperature probe up to the laser power approaching optical damage of Si.
ABSTRACTWe present time-resolved measurements of spontaneous anti-Stokes and Stokes Raman scattering during pulsed laser heating of crystalline silicon. The time-evolution of the lattice temperature is determined from the measured anti-Stokes/Stokes intensity ratio. In a separate calibration experiment we measure the temperature dependence of the anti-Stokes/Stokes ratio of an oven-heated silicon crystal from 300 K up to 900 K. The phase transition occuring during laser heating is detected by monitoring the changes of the optical reflectivity during laser irradiation. Our data suggest that the phase transition occurs at a lattice temperature of ∼600 K.