In situ ellipsometry of epitaxially grown bismuth antimony telluride on sapphire

Ellipsometry uses elliptically polarized light to characterize thin film and bulk materials. The light undergoes a change in polarization as it interacts with the sample structure. The measurement is typically expressed as two values: Psi (Ψ) and Delta (Δ). Bismuth telluride and its alloys are widely used as materials for thermoelectric and spintronic devices. This project uses in situ rotating compensator spectroscopic ellipsometer to measure properties of Bismuth Antimony Telluride ((BiSb)₂Te₃). If properties of bismuth antimony telluride such as thickness and composition can be determined by ellipsometry, it can be used as a tool to improve growth parameters in real-time, improving throughput and precision when growing these materials.