Competitive incorporation of oxygen and nitrogen into amorphous Nb–Ru–O–N

• Only low N contents in amorphous Nb–Ru–O–N are possible.
• Density functional theory was used to elucidate the growth mechanisms.
• O2 reacts fourfold more strongly than N2.
• N incorporation into amorphous Nb–Ru–O–N is energetically limited.

Amorphous Nb–Ru–O–N thin films were reactively synthesized with equal partial pressures of N2 and O2 to explore their competitive incorporation. The highest N content was obtained at low partial pressures, implying that there is a mechanism hindering the N incorporation. To elucidate the underlying growth mechanisms, density functional theory based molecular dynamics simulations were performed. O2 reacts with amorphous Nb–Ru–O–N fourfold more strongly than N2. At low partial pressures, there are enough surface sites to allow for N incorporation, while at higher partial pressures the N incorporation is inhibited by more reactive oxygen.