Laser technology for synthesis of AlN films: influence of the incident laser fluence on the films microstructure

Thin AlN films were synthesized by pulsed laser deposition at 800 °C by a KrF* excimer laser source (λ = 248 nm, τ = 25 ns, 3 Hz) at fluences of 4.8, 8.6 and 10 J/cm2 in nitrogen ambient at a dynamic pressure varying from 0.1 to 10 Pa. The film microstructurewas studied by X-ray diffractometry, while the film surface morphology of AlN films was examined by AFM imaging. At the low laser fluence (4.8 J/cm2), a stable hexagonal AlN phase was formed, while at the intermediate laser fluence (8.6 J/cm2), both hexagonal and metastable cubic crystallites were observed. At the high laser fluence (10 J/cm2), the films were XRD amorphous. The surface roughness shows a tendency to increase with the increase in the nitrogen pressure. The root-mean-square roughness values are 0. 2 - 5 nm, depending on N2 pressure.