Fe-N Thin Films Prepared by Excimer Laser Ablation

Fe-N films were deposited on glass substrates at room temperature using a pulsed KrF excimer laser (wavelength 248 nm, pulse width 27 ns). The film composition and structure depend on the ambient N
₂
pressure, the laser pulse energy, and the repetition rate. In order to understand the interaction between light-emitting ablated particles produced by excimer laser ablation of Fe and ambient N
₂
gas, the dynamics of ablated plumes were investigated by means of a high-speed framing streak camera and time-resolved emission spectroscopy. Two distinct components of ablated particles were observed. One consisted of a spherical plume with an average velocity of over 100 km/s, which was observed for about 300 ns from the laser irradiation. The other consisted of a columnar plume with a maximum velocity of 22 km/s, which was observed for 1 to 10 μs. The velocity of the Fe radicals depends on the N
₂
pressure, which contributes to formation of the Fe-N film.