Time resolved transmission and reflectivity of pulsed ruby laser irradiated silicon

The time resolved optical transmission, T (at lambda = 1152 nm), and reflectivity, R (at 633 nm and 1152 nm), were measured for n-type single crystalline silicon (C-Si) during and immediately after pulsed ruby laser irradiation (lambda = 693 nm, FWHM pulse duration 14 nsec), for a range of pulsed laser energy densities, E sub 1. The T is found to go to zero, and to remain at zero, for a period of time that increases with increasing E sub 1, in apparent disagreement with earlier measurements elsewhere that used semiinsulating Si and a different pulsed laser wavelength. Measured reflectivities during the high R phase agree within experimental error with reflectivities calculated from the optical constants of molten Si. Quantitative agreement is also found between both our T and R measurements and detailed time and E sub 1 dependent results of thermal melting model calculations.