Crystalline Quality and Surface Roughness Optimization of Hetero-Epitaxial Titanium Nitride on Sapphire.

In this project we optimized the growth of hetero-epitaxial titanium nitride (TiN) on sapphire using controllably unbalanced reactive magnetron sputtering. TiN is a mechanically-robust, high-temperature stable metallic material; these properties make TiN a material of interest for robust electrodes and resilient plasmonics. We adjusted deposition parameters such as external coil current, temperature, nitrogen/argon ratio, growth time and magnetron power to optimize the crystalline quality and surface morphology of TiN. Post-growth, we measured crystallinity using X-ray diffraction, and surface morphology using atomic force microscopy. X-ray diffraction showed a single TiN peak with pendell\"{o}sung fringes; from these fringes we obtained a film thickness of \textasciitilde 50 nm. Atomic force microscopy showed a surface roughness of \textasciitilde 168 pm. Based on this characterization, we determined that the deposition parameters outlined in this presentation yielded (111)-oriented epitaxial TiN with minimal surface roughness. This optimization is a crucial first step in maximizing TiN's usefulness in the above mentioned applications.