Structural characteristics of Bi₂Te₃ and Sb ₂Te₃ films on (001) GaAs substrates grown by MOCVD

Metal organic vapour phase epitaxy has been investigated for growth of Bi₂Te₃ and Sb₂Te₃ films on (001) GaAs substrates using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. High resolution TEM and x-ray diffraction patterns revealed that films had single crystalline phases with a preferential c-orientation and layered structures resulting from the van der Waals bonding nature in these materials. By optimizing growth parameters such as precursor ratio, growth temperatures, and flow rate in reactor, we could obtain Seebeck coefficient of -160μVK^-1 for Bi₂Te₃ and +110μVK^-1 for Sb₂Te₃ films, respectively. The high Seebeck coefficient and atomistically smooth surface morphologies of these materials are promising for the fabrication of a few nm thick periodic Bi₂Te₃/Sb₂Te₃ super lattice structures for thin film thermoelectric device applications.