Synthesis of nanocrystalline d-MoN by thermal annealing of amorphous thins films grown on (100) Si by reactive DC sputtering at room temperature.

We report on the synthesis and characterization of nanocrystalline d-MoN by recrystallization of amorphous thin films grown on (100) Si by DC sputtering at room temperature. Films with chemical composition MoN were grown by reactive sputtering using a deposition pressure of 5mTorr with a reactive mixture of Ar/(Ar+N2)=0.5. Initially the films display an amorphous structure with a residual-resistivity ratio (RRR = R300K/Ronset) ~ 0.8. After the thermal annealing at temperatures above 600 {\deg}C, the films crystallize in the hexagonal d-MoN phase and display RRR higher than 1. After annealing at 700 {\deg}C for 30 minutes, the films display nanometric grains (5-10 nm) and a superconducting critical temperature Tc = 11.2 K (close to the one reported for bulk specimens: 13 K). The films display very smooth surfaces, a property which is relevant for technological applications, such as the design of superconductive devices, i.e. Josephson tunnel junctions. Our results provide a simple method to synthesize superconducting thin films on silicon wafers with Tc above the ones observed for conventional superconductors such as Nb.