Direct measurement of the melt depth of silicon during laser irradiation

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Abstract
We have studied the change in morphology of laser irradiated silicon wafers by annihilating the oxygen thermal donors and the oxidation-induced stacking faults in order to verify the melting of the near-surface regions. The laser beam used was of 1.06 μm with a diameter of 40 μm, generated from a Q-switched neodymium:yttrium aluminum garnet (Nd:YAG) laser with a 150-ns pulse width and at a repetition rate of 12 kHz. Laser beam irradiation above about 6 J/cm2 annihilated both thermal donors and stacking faults, giving evidence of melting and suggesting that the annihilation of the thermal donors and of the stacking faults can be useful in studying the surface morphology in laser/electron beam irradiation.