Measurement of Thin Films by Optical Ellipsometry.

A specially designed ellipsometer was set up, aligned and calibrated. Using this equipment, air measurements were made on thin vacuum prepared films of tantalum, aluminum, and gold and the complex optical constants of these samples were calculated. Measurements were also made on thin films of anodized tantalum oxide, anodized aluminum oxide, sputtered aluminum oxide, and evaporated sapphire Al2O3. The refractive index and thickness of each oxide film were calculated using the exact Drude equations. A comparison of the results with published values indicated good agreement, but a general trend of increasing refractive index with film thickness was noted for tantalum oxide and an opposite trend was noted for both anodized aluminum oxide and evaporated sapphire. Suggested improvements include more care in sample preparation and some minor equipment and procedure modifications. Author