Metalorganic vapor phase epitaxy growth of ternary tetradymite Bi2Te3-xSex compounds

We report on a metal organic vapor epitaxy (MOVPE) of Bi2Te3-xSex films over the entire range of compositions (0 <= x <= 3) for the first time The films were grown on Al2O3(0001) substrates at 465 degrees C using trimethylbismuth (Bi2Me3), cliethyltellurium (Et2Te) and diisopropylselenium (iPro(2)Se) as metalorganic sources. To realize the 2D growth mode and to grow films with flat surfaces and high crystalline quality, a thin ZnTe buffer layer was used. As grown films were studied using optical and AFM microscopy techniques and X-ray diffraction. It was found that under steady growth conditions the composition of Bi2Te3-xSex films strongly depends on the film thickness. But a high rate of interdiffusion of chalcogens at the growth temperature rapidly leads to a homogeneous composition of the film in the growth direction. Dependence of the intensity of X-ray reflection (0012) on the composition of Bi2Te3-xSex films x has extremes near x=1 (Bi2Te2Se) and x=2 (Bi2Se2Te). The AFM micrographs and profiles show large (above 2 pm) triangle shaped atomically flat terraces with step height of a quintuple layer (0.90 nm) of the tetraclymite-type compounds. The electronic properties of the grown films have been characterized via four probe magnetotransport measurements. (C) 2014 Elsevier B.V. All rights reserved.