Evidence for phase-explosion and generation of large particles during high power nanosecond laser ablation of silicon

Publication Type

Journal Article

Date Published

02/2000

LBNL Report Number

LBNL-44782

Abstract

The craters resulting from high-irradiance (1×109–1×1011 W/cm2) single-pulse laser ablation of single-crystal silicon show a dramatic increase in volume at a threshold irradiance of 2.2×1010 W/cm2. Time-resolved shadowgraph images show ejection of large particulates from the sample above this threshold irradiance, with a time delay ∼300 ns. A numerical model was used to estimate the thickness of a superheated layer near the critical state. Considering the transformation of liquid metal into liquid dielectric near the critical state (i.e., induced transparency), the calculated thickness of the superheated layer at a delay time of 200–300 ns agreed with the measured crater depths. This agreement suggests that induced transparency promotes the formation of a deep superheated layer, and explosive boiling within this layer leads to particulate ejection from the sample.

Journal

Applied Physics Letters

Volume

76

Year of Publication

2000

Short Title

Appl. Phys. Lett.

Pagination

783-785

Issue

6