High ion irradiation tolerance of multilayered AlN/TiN nanocomposites

Structural stability of nanocrystalline (AlN/TiN)x5 multilayers upon argon ion irradiation was investigated. The layers were deposited on (100) Si wafers, to a total thickness of ∼270 nm. Argon ions were implanted at 200 keV, to the fluences from 5x1015 to 4x1016 ions/cm2. For comparison, metallic (Al/Ti)x5 multilayers were also deposited to similar thickness and irradiated with argon ions under the same conditions. It was found that (AlN/TiN)x5 multilayers exhibit a remarkable ion irradiation stability. Ion irradiation induces a slight increase of the mean grain size in individual layers, and small local density changes. Apart from this, no distinct intermixing of the layers was observed, the interfaces remaining flat and sharp. On the other hand, a pronounced interface mixing was observed in (Al/Ti)x5 multilayers, and formation of intermetallic phases for the highest irradiation fluence. The results suggest that immiscible metal-nitride multilayers should attract further attention as radiation tolerant materials. (author)