Influence of in situ nitrogen pressure on crystallization of pulsed laser deposited AlN films

Aluminum nitride (AlN) thin films obtained by pulsed laser deposition (PLD) with a KrF* laser source (l = 248 nm, t 7 ns) at a substrate temperature of 800 8C and different values of ambient nitrogen pressure up to 10 Pa have been studied. Precursors in the plasma plume were studied by optical multichannel emission spectroscopy. Emission spectra taken close to the target revealed the presence of atomic, single and multiple ionized Al and N species, as well as AlN molecular species. The analysis of the XRD patterns revealed that all films had a polycrystalline structure with mixed cubic and hexagonal phases. For AlN films deposited in vacuum, the structure is predominantly cubic with a small fraction of hexagonal phase. The cubic phase had a lattice parameter of 0.4045 nm. The films deposited in nitrogen ambient have a cubic crystalline structure. At maximum nitrogen pressure of 10 Pa the lattice parameter decreases to a = 0.3949 nm