Abstract

We report on the synthesis and characterization of nanocrystalline delta-MoN by crystallization of amorphous thin films grown on (100) Si by reactive sputtering at room temperature. Films with chemical composition MoN were grown using a deposition pressure of 5mTorr with a reactive mixture of Ar/(Ar + N-2) = 0.5. The as -grown films display mostly amorphous structure. Nanocrystalline delta-MoN phase is obtained after annealing at temperatures above 600 degrees C. The superconducting critical temperature T-c depends on film thickness. Thick films (170 nm) annealed at 700 degrees C for 30 min display a T-c = 11.2 K (close to the one reported for bulk specimens: 13 K), which is gradually suppressed to 7.2 K for 40 nm thick delta-MoN films. Our results provide a simple method to synthesize superconducting nitride thin films on silicon wafers with T-c above the ones observed for conventional superconductors such as Nb.