Reflectivity of crystalline Ge and Si at the melting temperature measured in real time with subnanosecond temporal resolution

Real time reflectivity measurements with subnanosecond time resolution have been used to determine the reflectivity at the melting temperature R-S(T-m ) of single crystalline Ge and Si at 514.5 nm. Due to the excellent time re solution and sensitivity achieved in a single exposure experiment, the refl ectivity of the solid just before melting could be measured. Values of R-S( T-m)=0.470 +/-0.006 and R-S(T-m)=0.440 +/-0.008 for c-Ge and c-Si have, res pectively, been determined. These values, together with those determined by heating in vacuum in the range 300-800 K, are compared to those reported e arlier in the literature and the differences are discussed. (C) 2001 Americ an Institute of Physics.