Kinetic limitation of chemical ordering in Bi2Te3−xSex layers grown by molecular beam epitaxy. (10th March 2016)

• Record Type: Journal Article
• Authors: Schreyeck, S; Brunner, K; Kirchner, A; Bass, U; Grauer, S; Schumacher, C; Gould, C; Karczewski, G; Geurts, J; Molenkamp, L W
• Is Part Of: Journal of physics. Volume 28:Number 14(2016)
• Publication Date: 2016-03-10
• Subjects: topological insulator -- epitaxy -- growth model -- chemical order -- bismuth telluride selenide alloy; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/28/14/145002
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We study the chemical ordering in Bi2 Te3− 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 Bi2 Te2 Se1 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.