CHARACTERISTICS OF THE SPECIES ABLATED FROM SILICON SURFACE BY PULSEDCO2-LASER IRRADIATION

Laser ablation of silicon surfaces with various dopant concentrations is studied by the irradiation of pulsed CO2 laser. Silicon ions with t he charge ranging from 1 to 4 au are observed in the emitted species. The fraction of the multiple charged ions increases with an increasing dopant concentration. The kinetic energy of Si ions, determined by th e time-of-flight measurement, extends up to similar to 300 eV, and is almost independent of the dopant concentration. The results can be exp lained by a positive charging of the irradiated spot during the laser irradiation.