  The effect of magnetron power on the room temperature 1.54 $\mu$m infra-red
photoluminescence intensity of erbium doped AlN films grown by r. f. magnetron
sputtering, has been studied. The AlN:Er thin films were deposited on (001)
Silicon substrates. The study presents relative photoluminescence intensities
of nanocrystallized samples prepared with identical sputtering parameters for
two erbium doping levels (0.5 and 1.5 atomic %). The structural evolution of
the crystallites as a function of the power is followed by transmission
electron microscopy. Copyright line will be provided by the publisher 1
Introduction For some time now, rare-earth (RE)-doped semiconductors represent
significant potential applications in the field of opto-electronic technology.
Part of this technological interest relies on the shielded 4f levels of the RE
ions as they give rise to sharp and strong luminescence peaks [1-5]. Among the
RE elements, Er is preferred to its counterparts since the Er ions can produce
both visible light at 558 nm (green, one of the primary colours) and IR light
at 1.54 $\mu$m whose spectrum region coincides with the main low-loss region in
the absorption spectrum of silica-based optical fibres, combining so potential
applications towards photonic devices and towards optical communication devices
operating in the infrared domain. These interesting emissions can however only
be exploited when placed into host matrixes. On one side, the shielding of the
intra 4f levels prevents the shifting of the RE 3+ energy levels and ensures
the frequency emission stability. Moreover the intra 4f transitions are parity
forbidden for the isolated ions. Matrixes can render the Er 3+ ions optically
active, via a relaxation of selection rules due to crystal field effects. As
silicon based materials were tested in the 1960s to the 90s with no clear
industrial success it was found that the
