کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5369574 | 1388443 | 2007 | 5 صفحه PDF | دانلود رایگان |
Single- and multi-shot ablation thresholds of gold films in the thickness range of 31-1400 nm were determined employing a Ti:sapphire laser delivering pulses of 28 fs duration, 793 nm center wavelength at 1 kHz repetition rate. The gold layers were deposited on BK7 glass by an electron beam evaporation process and characterized by atomic force microscopy and ellipsometry. A linear dependence of the ablation threshold fluence Fth on the layer thickness d was found for d â¤Â 180 nm. If a film thickness of about 180 nm was reached, the damage threshold remained constant at its bulk value. For different numbers of pulses per spot (N-on-1), bulk damage thresholds of â¼0.7 J cmâ2 (1-on-1), 0.5 J cmâ2 (10-on-1), 0.4 J cmâ2 (100-on-1), 0.25 J cmâ2 (1000-on-1), and 0.2 J cmâ2 (10000-on-1) were obtained experimentally indicating an incubation behavior. A characteristic layer thickness of Lc â 180 nm can be defined which is a measure for the heat penetration depth within the electron gas before electron-phonon relaxation occurs. Lc is by more than an order of magnitude larger than the optical absorption length of αâ1 â 12 nm at 793 nm wavelength.
Journal: Applied Surface Science - Volume 253, Issue 19, 31 July 2007, Pages 7815-7819