Abstract
High-power impulse magnetron sputtering (HiPIMS) was used to deposit titanium nitride (TiN) thin films with high electron density as alternative plasmonic materials. TiN thin films with thicknesses of 20–40 nm were deposited with different average sputtering powers, and exhibited metallic- and dielectric-like optical properties. When the sputtering power was increased from 80 W to 300 W, denser polycrystalline TiN thin films were obtained at room temperature (RT) with a conductivity 25 times that of the low-sputtering-power film. With sufficient average power (≥ 180 W), the films exhibited metallic-like optical properties, and a conductivity of >105 S/m. By using HiPIMS deposition, good-quality metallic-like TiN thin films could be fabricated at RT without heating the substrate.
Highlights
For plasmonic applications, traditional noble metals have a high loss problem, which affects the surface plasmon coupling excitation between photons and free-electrons [1]
In order to investigate the effect of High-power impulse magnetron sputtering (HiPIMS) on properties of the titanium nitride (TiN) thin films, the average power was fixed and the power density increased to 2 and 20 times the initial power density by adjusting the pulse on/off ratio (45/45 μs and 45/955 μs)
Under high power HiPIMS deposition, the sample deposited at a higher temperature could only experience a slight increase of the plasma frequency, which means that while using high power HiPIMS deposition, good quality metallic-like TiN thin films could be fabricated at room temperature (RT)
Summary
Traditional noble metals have a high loss problem, which affects the surface plasmon coupling excitation between photons and free-electrons [1]. There are additional advantages of transition metal nitrides such as chemical stability, high melting temperature, and tunable optical properties. These low-loss plasmonic materials have recently received a lot of attention. Due to the high-power input of a short pulse to the target, the high plasma density (1017 to 1019 m−3) is several orders of magnitude higher than that of conventional DC sputtering (1014 to 1016 m−3) [8]. There is another simple way to increase the plasma density by increasing the substrate bias voltage [9]. The relationships between electrical and optical properties of the TiN thin films are shown
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