DEPTH OF MELTING PRODUCED BY PULSED-LASER IRRADIATION

The depth of melt front penetration induced by Q-switched ruby-laser irradiation has been measured by electron microscopy for laser pulses of different duration and energy density in silicon crystals diffused with phosphorous. In as-diffused specimens (1100°C 1-h PH3 source) dislocation loops and phosphorous precipitates were distributed to a depth of about 1.0 μm. The precipitates and loops were dissolved to certain depths by irradiation with Q-switched ruby-laser pulses. Dissolving of precipitates provides evidence for melting by the laser radiation, and the depth over which precipitates are dissolved provides a measure of the melt front penetration depth.