Formation Of Mobile Hydridic Defects In Zirconium Nitride Films With N-Type Semiconductor Properties

The incorporation of mobile hydridic defects was demonstrated for low-crystalline zirconium nitride (Zr3N4-delta) films deposited by radio frequency reactive sputtering under a flow of nitrogen-rich reactive gases. Extended X-ray adsorption fine structure analysis confirmed that the local coordination environment around the Zr atoms was very close to that of the orthorhombic Eu3O4 phase. Pristine Zr3N4-delta films exhibited n-type semiconductor behavior due to the presence of nitrogen vacancy donors with a carrier concentration of 1.4 x 10(20) cm(-3) and an electron mobility of 2.2 x 10(-3) cm(2) V-1 s(-1) at room temperature. Electrochemical and spectroscopic measurements confirmed that Zr3N4-delta was readily hydrogenated upon exposure to H-2 gas at 300 degrees C to form hydridic defects via electron donation to hydrogen adatoms. Hence, the hydrogenated film exhibited H- ion/electron mixed conductor behavior in a H-2 atmosphere. These findings open the possibility for exploring new hydride ion conductors based on thermodynamically stable transition metal nitrides.