Fe-N Thin Films Prepared by Excimer Laser Ablation.

Fe-N films were deposited on glass substrates at room temperature by using a pulsed KrF excimer laser (wavelength = 248 nm. pulse width = 27 ns). The film composition and structure depend on the ambient N2 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 N2 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 consists of a spherical plume with an average velocity of over 100 km/s, which is observed for about 300 ns from the laser irradiation. The other consists of a columnar plume with a maximum velocity of 22 km/s, which is observed for 1∼10μs. The velocity of Fe radicals depends on the N2 pressure, which contributes to the form action the of Fe-N film.