Optical and Structural Characterization of ScO_xN_y and ScSi_zO_xN_y Thin Films as Dispersion Engineered Optical Materials

The development of compact diffractive optical elements with tailored optical phases has revolutionized the field of photonics, enabling the creation of high-efficiency photonic components with unprecedented functionalities. This research contributes to developing novel ScO_xN_y and ScSi_zO_xN_y thin films, providing valuable insights into their optical properties, structural characteristics, and patterning potential. We studied the optical and structural properties of ScO_xN_y and ScSi_zO_xN_y thin films, synthesized using reactive RF magnetron sputtering. By modulating the growth conditions and incorporating SiO₂ components through co-deposition and post-deposition annealing, we achieve tunability in the optical constants of the materials with refractive indices ranging from 1.7 to 3 with negligible absorption losses across the visible spectral range. Variable angle spectroscopic ellipsometry (VASE) is employed to determine the dielectric function of each sample in a broad spectral range extended from the ultraviolet to the mid infrared wavelengths. Furthermore, the structural properties of the thin films are investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). These characterization techniques provide insights into the surface morphology, crystal structure, and composition of the films, essential for understanding their optical performances. In addition, our study explores the suitability of different reactive ion etching (RIE) processes for the fabrication of nanopatterns in these materials. The etching behaviour and selectivity of the thin films is investigated with an aim to identify optimal etching conditions for achieving precise patterning and integration into functional photonic devices such as ultracompact imaging components and broadband dielectric metasurfaces.