Annealing Impact on the Evolution of Crystalline Phases and Emission in Si-Rich HfO2:Nd Films Obtained By Magnetron Sputtering

Abstract

Hafnium oxide films doped with Si and Nd atoms have been produced by radio-frequency magnetron sputtering in pure argon plasma followed by an annealing in nitrogen atmosphere for 1-60 minutes at the temperature 1000 °C. The effect of post-deposition thermal annealing on the transformation of crystalline phases and photoluminescence spectra was investigated by the non-destructive methods (scanning electronic microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman scattering and photoluminescence(PL)). The XRD analysis of these samples demonstrate the phase separation process which depends on the time range and the annealing temperature. In the studed samples, the formation of the tetragonal HfO2, tetragonal SiO2 and cubic Si phases was observed by XRD and confirmed by the Raman study. Thermal annealing influents also on PL spectra where the main bands were detected at 380, 450, 550, 780 and 880 nm. The emission and excitation mechanisms for the Nd radiative defects, and the impact of phase transformation in studied films, are analyzed and discussed.