Properties of zinc oxynitride films deposited by reactive magnetron sputtering at room temperature

Abstract

The optical, structural, and electrical properties of zinc oxynitrides grown by reactive rf magnetron sputtering are investigated. Oxygen and nitrogen compositions in the layers varied from 55% to 0% and 3% to 44%, respectively, thus ranging from N-doped ZnO to pure Zn₃N₂. A ZnO layer is included atop of the films to prevent N loss. Rutherford backscattering shows the increase of Zn as well as the reduction of O in the alloy as the N content increases. X-ray diffraction measurements evidence the deformation of the wurtzite lattice as the N is introduced, showing a strong impact on the c parameter of the unit cell. Intermediate N contents reduce the crystal quality giving rise to quasi-amorphous layers. Optical transmission measurements were used to determine the absorption cut-off wavelength as a function of N content. The type of spectrum obtained for a N content of 4% along with the observed morphology seem to point out to the existence of two phases. For similar O and N concentrations, the X-ray pattern yields features of a new crystal phase. For these compositions, electrical characterization exhibits a minimum resistivity of 0.42 Ω cm.