Influence of the growth conditions of AlN and GaN films by reactive laser ablation

We report on AlN and GaN film growth by laser ablation of Al or Ga targets, respectively, in N2 reactive ambient atmosphere. The best experimental conditions are defined in relation with film. Due to the low chemical reactivity of N2, it is necessary to increase N density to obtain pure nitride films to realise high quality films. Thus a radio frequency (RF) discharge device was added for N2 dissociation. AlN and GaN hexagonal nitride phases and highly textured AlN films with epitaxial relationships with (0 0 0 1) Al2O3 substrates are grown without contamination. The plasma plume investigation by emission spectroscopy with and without RF discharge allows the reactive species kinetics study near the target. A secondary discharge device is mounted at the place of the substrate holder to study the dark zone near the substrate. The presence of N metastable species near the substrate has been evidenced as well as the increase of their concentration with RF discharge added.