title: Kinetic limitation of chemical ordering in Bi2Te3-x Se x layers grown by molecular beam epitaxy.
abstract: We study the chemical ordering in Bi2Te3-x Se x grown by molecular beam epitaxy on Si substrates. We produce films in the full composition range from x = 0 to 3, and determine their material properties using energy dispersive x-ray spectroscopy, x-ray diffraction and Raman spectroscopy. By fitting the parameters of a kinetic growth model to these results, we obtain a consistent description of growth at a microscopic level. Our main finding is that despite the incorporation of Se in the central layer being much more probable than that of Te, the formation of a fully ordered Te-Bi-Se-Bi-Te layer is prevented by kinetic of the growth process. Indeed, the Se concentration in the central layer of Bi2Te2Se1 reaches a maximum of only ≈ 75% even under ideal growth conditions. A second finding of our work is that the intensity ratio of the 0 0 12 and 0 0 6 x-ray reflections serves as an experimentally accessible quantitative measure of the degree of ordering in these films.
authors.affiliation: Physikalisches Institut, Experimentelle Physik 3 and Wilhelm-Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schreyeck
authors.forename: K
authors.initials: K
authors.lastname: Brunner
authors.forename: A
authors.initials: A
authors.lastname: Kirchner
authors.forename: U
authors.initials: U
authors.lastname: Bass
authors.forename: S
authors.initials: S
authors.lastname: Grauer
authors.forename: C
authors.initials: C
authors.lastname: Schumacher
authors.forename: C
authors.initials: C
authors.lastname: Gould
authors.forename: G
authors.initials: G
authors.lastname: Karczewski
authors.forename: J
authors.initials: J
authors.lastname: Geurts
authors.forename: L W
authors.initials: LW
authors.lastname: Molenkamp