Rapid formation of nanostructures in Au films using a CO2 laser

Abstract

We systematically investigate the formation of nanostructures in magnetron-sputtered Au films using a CO2 laser. By comparing the optical properties and surface morphologies of Au films on different kinds of substrates before and after laser irradiation with different laser powers and irradiation times, we find that the nanostructures are most rapidly formed in the Au film with 5 nm thickness on a thin glass substrate. With the laser power of 6 W and a beam diameter of ~10 mm at the Au film, only a few tens of seconds of irradiation time is sufficient to induce nanostructures with the area size of ~10 mm in the 5 nm Au film on a thin glass substrate.

Surface plasmon resonance tuning of Ag nanoisland films using a CO2 laser

“…To ensure the maximum absorption of laser energy by the glass substrate the laser is irradiated from the back side (i.e., glass side) of the film. In reality, however, whether the CO 2 laser is irradiated from the front or back side of the film does not matter if the film thickness is 5 nm, but it matters if it is beyond ∼7 nm [29]. The temperature of the Ag film during laser irradiation is measured using a thermocouple with a size of ∼1 mm.…”

“…Recently a focused CO 2 laser beam has been employed to induce nanostructures in thin films [27,28]. More recently we have demonstrated that the irradiation of a non-focused CO 2 laser beam with a power density of 4∼6 W/cm 2 to a 5 nm Au film on a glass substrate for several seconds is sufficient to induce Au nanostructures [29]. Knowing that CO 2 laser annealing of thin Au films works well, how it works for thin Ag films is an interesting question, since they are also frequently used for many applications.…”

“…Compared with the relatively simple and straightforward well-known technique to tune the wavelength of SPR of noble metal films through the deposition rate, film thickness, and substrate temperature [30], our technique offers a simple and quick alternative, since a nanostructured Ag film with a SPR at the desired wavelength can be fabricated on demand from the Ag films which have been prepared beforehand under the same sputtering condition. Perhaps more interestingly, the reduction of the height of SPR set in after the 30 sec irradiation at 3 W for Ag films and it almost disappears after the 10 min irradiation if the laser power is 5 W, while it did not happen for Au films up to the 1 min irradiation even at 6 W [29]. The gradual loss of plasmon color, which means the disappearance of Ag NIs, at the irradiation center on the film implies that the diffusion of Ag atoms over the macroscopic distance occurs during the laser irradiation, and this interpretation is confirmed by the SEM analysis: Lesser and lesser Ag NIs are observed at the irradiation center as the irradiation time becomes longer.…”

Antifungal Properties of Pure Silver Films with Nanoparticles Induced by Pulsed-Laser Dewetting Process

“…The feasibility of pulsed laser-induced dewetting, especially using nanosecond pulses, has attracted significant attention in the literature [24][25][26][27][28][29][30]. However, only scant information is available regarding the synthesis of metallic NPs using a high repetition rate laser.…”

Antibacterial Properties of Pure Silver Films with Nanoparticles Induced by Pulsed-Laser Dewetting Process

“…The feasibility of pulsed laser-induced dewetting, especially that using nanosecond pulses, has attracted significant attention in the literature [24][25][26][27] . However, only scant information is available regarding the synthesis of metallic NPs using a high repetition rate laser.…”