Dopant and fluence effects on the ablation of silicon surfaces under pulsed CO laser irradiation

Effects of impurity doping and laser-pulse fluence on the laser ablation of silicon wafers are studied by using a TEA CO2 laser. Silicon ions with charge from 1 to 4 a.u. were observed in the ablation species. The average ion charge increased with dopant concentration and the laser fluence. The velocity of the ions depends on the fluence and slightly on the dopant concentration. The electric current flowing from a target into the ground level was also measured and showed dopant and fluence effects. The correlation among these experiments is examined and the ablation mechanism is discussed. q1998 Elsevier Science B.V.