Optical properties of Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ grown by metalorganic vapor phase epitaxy

In this work, we present the optical constants of bismuth telluride (Bi/sub 2/Te/sub 3/), and antimony telluride (Sb/sub 2/Te/sub 3/) determined using spectroscopic ellipsometry (SE). Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ films with different thicknesses were grown by metalorganic chemical vapor deposition (MOCVD). Multiple sample analysis (MSA) technique was employed in order to eliminate the parameter correlation in the SE data analysis caused by the presence of the overlayer on top of Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ films. Optical constants and thicknesses for both Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ overlayers were also determined. Independent Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ samples were used to check the results obtained. In addition, two Sb/sub 2/Te/sub 3/ samples were analyzed using SE after being etched in diluted NH/sub 4/OH solution in order to characterize the overlayer and confirm the reliability of the results. In-situ growth of Bi/sub 2/Te/sub 3/-Sb/sub 2/Te/sub 3/ superlattices was simulated using the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ optical constants we obtained to study the possibility of in-situ monitoring and controlling the growth of Bi/sub 2/Te/sub 3/-Sb/sub 2/Te/sub 3/ superlattice using spectroscopic ellipsometer.