Laser ablation of solid substrates in a water-confined environment

Zhu, S Lu, YF Hong, MH

S. Zhu et al., Laser ablation of solid substrates in a water-confined environment, APPL PHYS L, 79(9), 2001, pp. 1396-1398

15

INGLESE

Article

Apllied Physucs/Condensed Matter/Materiales Science

APPLIED PHYSICS LETTERS

0003-6951 → ACNP

79

9

2001

1396 - 1398

ISI

0003-6951(20010827)79:9<1396:LAOSSI>2.0.ZU;2-K

Laser ablation of Si under a water surface has been investigated. The laser used is a KrF excimer laser, which has a wavelength of 248 nm and a pulse duration of 23 ns. It is found that the laser ablation rate of Si varies wi th the thickness of the water layer above the Si substrates. The laser abla tion rate is the most highly enhanced with a water layer of 1.1 mm. It is a ssumed that the plasma generated in the water confinement regime with an op timal water layer thickness induces the strongest pressure. This high-press ure, high-temperature plasma results in the highest ablation rate. A wide-b and microphone is used to detect the audible acoustic wave generated during the laser ablation. The amplitude of the acoustic wave is closely related to the ablation rate. It is found that the first peak-to-peak amplitude of the acoustic wave is the strongest when the water layer thickness is 1.1 mm above the substrate. Fast Fourier transform analysis of the wave forms sho ws that there are several frequency components included in the acoustic wav es. The dominant frequency component decreases from 10.6 to 3.5 kHz as the water layer thickness varies from 1 to 2.2 mm. Diagnostics of the acoustic wave emission can be used to find the optimal water layer thickness to enha nce the laser ablation rate. With proper calibration, acoustic-wave detecti on can be used as a real-time monitoring of the laser ablation. (C) 2001 Am erican Institute of Physics.