Optical-pyrometric diagnostics of the state of silicon during nanopulsed laser irradiation

The dynamics of the reflectivity at $\lambda$ = 0.53 $\mu$m and the IR radiation of silicon in the wavelength range 0.9–1.2 $\mu$m is studied under the action of nanosecond ruby laser radiation pulses. When radiation energy density W is lower than the threshold of laser-induced melting of the surface of a semiconductor crystal, the major contribution to the IR radiation emitted by this crystal is made by edge photoluminescence. As the melting threshold is exceeded, the nanosecond dynamics of the detected IR radiation changes from photoluminescence to the thermal radiation of the forming Si phase melt with a high reflectivity. The results of pyrometric measurements of the peak melt surface temperature as a function of W obtained at an effective wavelength $\lambda_e$ = 1.04 $\mu$m of the detected IR radiation agree with the data of analogous measurements performed at $\lambda_e$ = 0.53 and 0.86 $\mu$m.