Effect of Annealing on Surface Morphology and Wettability of NC-FeSi₂ Films Produced via Facing-Target Direct-Current Sputtering.

Nanocrystalline iron disilicide (NC-FeSi₂) films were created at room temperature by facing-target direct current sputtering. The NC-FeSi₂ films were annealed at different temperatures of 300 °C, 600 °C, and 900 °C under high vacuum for 2 hours. XRD results of the as-created NC-FeSi₂ films after annealing at 300 °C showed a broad peak at 2 ranging from 40° to 50°. NC-FeSi₂ films annealed at 600 and 900 °C consisted of several preferred orientations with improved crystallinity. Peaks of Raman lines for unannealed and annealed NC-FeSi₂ films were observed at approximately 176 and 232 cm, respectively. Based on FESEM micrographs in plane view, unannealed NC-FeSi₂ films were composed of many small uniform crystallites with diameters of 5-7 nm. At an annealing temperature of 300 °C the small uniform crystallites merged and formed small nanocrystalline clusters, while at annealing temperatures higher than 300 °C they grouped together as large clusters. An AFM of unannealed NC-FeSi₂ films showed a very smooth surface with a root mean square roughness of 0.81 nm which increased by annealing. Unannealed NC-FeSi₂ film surface exhibited an average contact angle of 100.1°, which was hydrophobic. At an annealing temperature of 300 °C, the film surface exhibited the highest contact angle of 106.2°. Average contact angles decreased at annealing temperatures higher than 300 °C.