Plasmonic Titanium Nitride via Atomic Layer Deposition: A Low-Temperature Route

Abstract: To integrate plasmonic devices into industry, it is essential to develop scalable and CMOS compatible plasmonic materials. In this work, we report high plasmonic quality titanium nitride (TiN) on c-plane sapphire by plasma enhanced atomic layer deposition (PE-ALD). TiN with low losses and high metallicity was achieved at temperatures below 500{\deg}C, by exploring the effects of chemisorption time, substrate temperature and plasma exposure time on material properties. Reduction in chemisorption time mitigates premature precursor decomposition at T_S > 375{\deg}C , and a trade-off between reduced impurity concentration and structural degradation caused by plasma bombardment is achieved for 25s plasma exposure. 85 nm thick TiN films grown at a substrate temperature of 450{\deg}C, compatible with CMOS processes, with 0.5s chemisorption time and 25s plasma exposure exhibited a high plasmonic figure of merit (|{\epsilon}^'/{\epsilon}^''|) of 2.8 and resistivity of 31 {\mu}{\Omega}-cm. These TiN thin films fabricated with subwavelength apertures were shown to exhibit extraordinary transmission.