Structural and mechanical properties changes induced in nanocrystalline ZrC thin films by Ar ion irradiation

Thin ZrC films (<500 nm), grown on (100) Si substrates at a substrate temperature of 500 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser, were irradiated by 800 keV Ar ion at room temperature under a fixed flux of 10 ¹¹ cm ² s ⁻¹ with fluences ranging from 1 × 10 ¹⁴ at/cm ² to 2 × 10 ¹⁵ at/cm ² . Glancing incidence X-ray diffraction, X-ray reflectivity, transmission electron microscopy and nanoindentation investigations were used to study the structural modifications in the films` density, composition and mechanical properties induced by irradiation. After irradiation, the lattice parameter and crystallite size slightly increased, while the films` density decreased. Significant decreases in nanohardness and Young modulus values were also measured after irradiation at 1 × 10 ¹⁴ at/cm ² and 1 × 10 ¹⁵ at/cm ² fluences. No further major decreases were observed for a fluence of 2 × 10 ¹⁵ at/cm ² . Scanning transmission electron microscopy and energy dispersive X-ray analysis showed a decrease in the Zr/C values in the irradiated film from surface towards the Si substrate.