Preparation of High Quality Single Crystal (001) Ir Films on (11‐20) Sapphire Substrate

For heteroepitaxial single‐crystal diamond growth, iridium is recognized as the optimal nucleation layer due to its unique carbon‐saturated precipitation mechanism that facilitates the formation of highly oriented and dense diamond nuclei. This study employed magnetron sputtering to deposit iridium on (11‐20) a‐plane sapphire substrates, systematically investigating the effects of deposition temperature, sputtering power, and rapid high‐temperature annealing on the orientation, surface morphology, and film quality of Ir. Experimental results demonstrated that (100)‐oriented Ir films are successfully achieved at a deposition temperature of 780°C with 125 W sputtering power. Subsequent rapid thermal annealing at 1000°C significantly improved the crystalline quality, evidenced by the reduction of FWHM for Ir (002) XRD rocking curve from 436 to 323 arcsec. TEM analysis confirmed the single‐crystal nature of Ir films with minimal lattice strain. This achievement of high‐quality Ir films establishes a crucial foundation for optimizing the quality of subsequent heteroepitaxial single‐crystal diamond growth. The fabrication of high‐quality, highly‐oriented iridium films serves as an essential prerequisite for the successful nucleation and growth of high‐quality heteroepitaxial diamond. This study demonstrates the deposition of Ir on 2‐inch sapphire, thereby representing a critical step toward the realization of heteroepitaxial single‐crystal diamond at the 2‐inch scale and beyond.