TY - JOUR KW - Model KW - Target KW - Measurements KW - Measurement KW - USA KW - Surface KW - Pulse KW - Diffusion KW - Ablation KW - Laser KW - Laser ablation KW - Laser ablation KW - Analysis KW - Intensities KW - Intensity KW - Time KW - Ca KW - E KW - Mass KW - Plasma KW - Laser pulses KW - Pulses KW - C KW - Crater KW - Mechanism KW - Nanosecond KW - Phase KW - Thermal KW - Ha KW - Nanosecond laser KW - Depth KW - Explosion KW - Silicon KW - Threshold KW - Particulates KW - Circulation KW - Irradiation KW - Laser irradiation KW - Phase explosion KW - Phase-explosion KW - Physics KW - Single-crystal KW - Thermal diffusion AU - Quanming Lu AU - Samuel S Mao AU - Xianglei Mao AU - Richard E Russo AB -

An important parameter for high-irradiance laser ablation is the ablation crater depth, resulting from the interaction of individual laser pulses on a targeted surface. The crater depth for laser ablation of single-crystal silicon shows a dramatic increase at a laser intensity threshold of approximately 2x1010 W/cm2, above which, large (micron-sized) particulates were observed to eject from the target. We present an analysis of this threshold phenomenon and demonstrate that thermal diffusion and subsequent explosive boiling after the completion of the laser pulse is a possible mechanism for the observed dramatic increase of the ablation depth. Calculations based on this delayed phase explosion model provide a satisfactory estimate of the measurements. In addition, we find that the shielding of an expanding mass plasma during laser irradiation has a profound effect on this threshold phenomenon. (C) 2002 American Institute of Physics

AD -

Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA

BT - Applied Physics Letters C2 - LBNL-49967 DO - 10.1063/1.1473862 IS - 17 LA - eng LB - Laser N2 -

An important parameter for high-irradiance laser ablation is the ablation crater depth, resulting from the interaction of individual laser pulses on a targeted surface. The crater depth for laser ablation of single-crystal silicon shows a dramatic increase at a laser intensity threshold of approximately 2x1010 W/cm2, above which, large (micron-sized) particulates were observed to eject from the target. We present an analysis of this threshold phenomenon and demonstrate that thermal diffusion and subsequent explosive boiling after the completion of the laser pulse is a possible mechanism for the observed dramatic increase of the ablation depth. Calculations based on this delayed phase explosion model provide a satisfactory estimate of the measurements. In addition, we find that the shielding of an expanding mass plasma during laser irradiation has a profound effect on this threshold phenomenon. (C) 2002 American Institute of Physics

PY - 2002 SP - 3072 EP - 3074 ST - Appl. Phys. Lett. T2 - Applied Physics Letters TI - Delayed phase explosion during high-power nanosecond laser ablation of silicon VL - 80 ER -