Metrology of Iron Thin Films for CNT growth via Ellipsometry

Fe thickness serves as a critical determinant in CNT growth, and spectroscopic ellipsometry measurements provide a rapid, accessible approach for evaluating thin film thickness. However, Fe thickness measurements are challenging due to unknown relative proportion of metallic Fe and its oxidized form. As deposited Fe oxidizes upon air exposure, its optical response evolves. To improve the accuracy of thickness modeling, Fe films of varying initial thicknesses (2 to 10nm) are annealed at 300C until full oxidation is achieved. Intermittent atomic force microscopy (AFM) scans are conducted to monitor surface morphology and confirm the absence of Fe beading, ensuring a smooth topography. Complete oxidation is verified via X-ray photoelectron spectroscopy (XPS) following thermal annealing.