Monitoring (Bi_1-xIn_x)Se3 thin film thickness and composition in-situ with Spectroscopic Ellipsometry

Heterostructures of (Bi_1-xIn_x)Se₃, Bi₂Se₃, and In₂Se₃ were grown via Molecular Beam Epitaxy and monitored in-operando using in-situ Spectroscopic Ellipsometry. A W-Vase software model was created to fit the thickness and composition from x=0 to x=1 in (Bi_1-xIn_x)Se₃. This model was used during growth on Penn State University’s MBE2 machine, determining the thickness and composition of each film. The purpose of these growths was to update and improve the model and test the model for universality among MBE systems. As growths were completed, the accuracy of the model improved. It was tested on a different MBE system (MBE1), showing the model is transferable between systems. Sticking and desorption coefficients of Bismuth Selenide were also explored using the thickness output of the model.