In-situ monitoring of the growth of Bi2Te3 and Sb2Te3 films and Bi2Te3-Sb2Te3 superlattice using spectroscopic ellipsometry

In this work, we present in-situ monitoring of the growth of bismuth tellur ide (Bi2Te3) and antimony telluride (Sb2Te3) thin films as well as Bi2Te3-S b2Te3 superlattice using a spectroscopic ellipsometer (SE). Bi2Te3 and Sb2T e3 films were grown by metalorganic chemical vapor deposition (MOCVD) at 35 0 degreesC. A 44-wavelength ellipsometer with spectral range from 404 nm to 740 nm was used in this work. The optical constants of Bi2Te3 and Sb2Te3 a t growth temperature were determined by fitting a model to the extracted in -situ SE data of optically thick Bi2Te3 and Sb2Te3 films. Compared to the o ptical constants of Bi2Te3 and Sb2Te3 at room temperature, significant temp erature dependence was observed. Using their optical constants at growth te mperature, the in-situ growth of Bi2Te3 an Sb2Te3 thin films were modeled a nd excellent fit between the experimental data arid data generated from the best-fit model was obtained. In-situ growth of different Bi2Te3-Sb2Te3 sup erlattices was also monitored and modeled. The growth of Bi2Te3 and Sb2Te3 layers can be seen clearly in in-situ SE data. Modeling of in-situ superlat tice growth shows perfect superlattice growth with an abrupt interface betw een the two constituent films.