SURFACE-MORPHOLOGY AND STRUCTURAL MODIFICATIONS OF SI TARGETS SUBMITTED TO INTENSE PULSED-LASER IRRADIATIONS

Crystalline silicon samples (with or without their native oxide layer) have been submitted to intense optical irradiations generated by lase r sources delivering pulses of different durations (in the ns or Irs r egimes) in the visible (approximate to 550 nm) or in the near infrared (approximate to 1000 nm). The different stages of the morphological s urface alterations and the possible inherent structural modifications were studied as a function of the incident energy fluence using optica l or electronic microscopies and Raman scattering. For both types of s amples, special attention was paid to the determination of the thresho ld fluence for surface melting and these results were compared with pr edictions obtained by solving the one-dimensional time-dependent heat- flow equation. Raman investigations have revealed that, excepted for s pecific locations in the crater boundary, the irradiated area presents a good crystalline quality.