Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

Abstract

The paper presents an investigation of deformation response of monocrystalline silicon surface to the action of short laser pulses in the air and in vacuum P 1 0-2 Ton. An anomalously continuous change of the surface relief was identified on irradiation in the air. The observable phenomenon is explained by oxidation of surface layer, enriched with defects.

Thermocapillary mechanism of melt displacement during keyhole formation by the laser beam

“…For beam diameter d = 0.7 mm in the irradiance range q = (0.5-1.0) × 10 10 W m −2 we will obtain a change in the maximum rate of thermocapillary flow in the interval V ≈ 4.9-6.9 m s −1 (it corresponds to average speed of moving layer 0.5V ≈ 2.4-3.4 m s −1 ) and the speed of the motion of the bottom V S ≈ 0.51-0.60 m s −1 . The values obtained correspond to the empirical observations V ∼ 2 m s −1 [21] and V S ≈ 0.5-0.6 m s −1 [22].…”

“…Steel [3,4] Iron [23] Liquid (table 1) and compare them with empirical data [21,22]. For radial geometry the speed of the motion of the bottom due to thermocapillary radial spreading from the centre of the beam impact zone can be approximately written as V S ≈ 4V h/d.…”