Work function measurement of transition metal nitride and carbide thin films

Work functions of rf-magnetron sputter-deposited transition metal nitride and carbide thin films, including TiN, HfN, VN, NbN, TaN, HfC, VC, NbC, TaC, Cr3C2Cr3C2, and WC, were measured by Kelvin probe in air. Thin films of the above materials were prepared on (1 0 0)-oriented silicon substrate by rf-magnetron sputtering of a compound target. As a result, it was found that the work function of nitride was similar to or slightly lower than that of carbide. For nitride films, those with heavier metal atoms such as Hf and Ta, showed lower work function. The work function depended upon the Period to which the metal atom belongs in the periodic table.