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Title: Transport properties of Bi 2 (Se 1−x Te x ) 3 thin films grown by molecular beam epitaxy

Authors:
 [1];  [1];  [1];  [1]
  1. Department of Materials Science and Engineering, University of Delaware, 127 The Green Room 201, Newark, Delaware 19716
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1420692
Grant/Contract Number:
SC0016380
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. B, Nanotechnology and Microelectronics
Additional Journal Information:
Journal Volume: 35; Journal Issue: 2; Related Information: CHORUS Timestamp: 2018-02-14 18:30:41; Journal ID: ISSN 2166-2746
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English

Citation Formats

Wang, Yong, Ginley, Theresa P., Zhang, Chiyu, and Law, Stephanie. Transport properties of Bi 2 (Se 1−x Te x ) 3 thin films grown by molecular beam epitaxy. United States: N. p., 2017. Web. doi:10.1116/1.4976622.
Wang, Yong, Ginley, Theresa P., Zhang, Chiyu, & Law, Stephanie. Transport properties of Bi 2 (Se 1−x Te x ) 3 thin films grown by molecular beam epitaxy. United States. doi:10.1116/1.4976622.
Wang, Yong, Ginley, Theresa P., Zhang, Chiyu, and Law, Stephanie. Wed . "Transport properties of Bi 2 (Se 1−x Te x ) 3 thin films grown by molecular beam epitaxy". United States. doi:10.1116/1.4976622.
@article{osti_1420692,
title = {Transport properties of Bi 2 (Se 1−x Te x ) 3 thin films grown by molecular beam epitaxy},
author = {Wang, Yong and Ginley, Theresa P. and Zhang, Chiyu and Law, Stephanie},
abstractNote = {},
doi = {10.1116/1.4976622},
journal = {Journal of Vacuum Science and Technology. B, Nanotechnology and Microelectronics},
number = 2,
volume = 35,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1116/1.4976622

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  • The effects of Mn doping on the structural properties of the topological insulator Bi{sub 2}Se{sub 3} in thin film form were studied in samples grown via molecular beam epitaxy. Extended x-ray absorption fine structure measurements, supported by density functional theory calculations, indicate that preferential incorporation occurs substitutionally in Bi sites across the entire film volume. This finding is consistent with x-ray diffraction measurements which show that the out of plane lattice constant expands while the in plane lattice constant contracts as the Mn concentration is increased. X-ray photoelectron spectroscopy indicates that the Mn valency is 2+ and that the Mnmore » bonding is similar to that in MnSe. The expansion along the out of plane direction is most likely due to weakening of the Van der Waals interactions between adjacent Se planes. Transport measurements are consistent with this Mn{sup 2+} substitution of Bi sites if additional structural defects induced by this substitution are taken into account.« less
  • Structural properties of topological insulator bismuth telluride films grown epitaxially on (111) BaF{sub 2} with a fixed Bi{sub 2}Te{sub 3} beam flux were systematically investigated as a function of substrate temperature and additional Te flux. A layer-by-layer growth mode is observed since the early stages of epitaxy and remains throughout the whole deposition. Composition of the epitaxial films produced here stays between Bi{sub 2}Te{sub 3} and Bi{sub 4}Te{sub 5}, as determined from the comparison of the measured x-ray diffraction curves with calculations. The substrate temperature region, where the growth rate remains constant, is found to be the most appropriate tomore » obtain ordered Bi{sub 2}Te{sub 3} films. Line width of the L = 18 Bi{sub 2}Te{sub 3} diffraction peaks as low as 140 arcsec was obtained, indicating high crystalline quality. Twinning domains density rises with increasing growth temperature and reducing Te extra flux. X-ray reflectivity curves of pure Bi{sub 2}Te{sub 3} films with thickness from 165 to 8 nm exhibited well defined interference fringes, evidencing homogeneous layers with smooth surface. Our results demonstrate that Bi{sub 2}Te{sub 3} films with very well controlled structural parameters can be obtained. High structural quality Bi{sub 2}Te{sub 3} films as thin as only eight quintuple layers grown here are promising candidates for intrinsic topological insulator.« less
  • Thin films of Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} have been grown on deoxidized GaAs(001) substrates using molecular beam epitaxy. Cross-sectional transmission electron microscopy established the highly parallel nature of the Te(Se)-Bi-Te(Se)-Bi-Te(Se) quintuple layers deposited on the slightly wavy GaAs substrate surface and the different crystal symmetries of the two materials. Raman mapping confirmed the presence of the strong characteristic peaks reported previously for these materials in bulk form. The overall quality of these films reveals the potential of combining topological insulators with ferromagnetic semiconductors for future applications.
  • We report a systematic study on the structural and electronic properties of Bi{sub 2}Te{sub 3−x}Se{sub x} topological insulator alloy grown by molecular beam epitaxy (MBE). A mixing ratio of Bi{sub 2}Se{sub 3} to Bi{sub 2}Te{sub 3} was controlled by varying the Bi:Te:Se flux ratio. X-ray diffraction and Raman spectroscopy measurements indicate the high crystalline quality for the as-grown Bi{sub 2}Te{sub 3−x}Se{sub x} films. Substitution of Te by Se is also revealed from both analyses. The surfaces of the films exhibit terrace-like quintuple layers and their size of the characteristic triangular terraces decreases monotonically with increasing Se content. However, the triangularmore » terrace structure gradually recovers as the Se content further increases. Most importantly, the angle-resolved photoemission spectroscopy results provide evidence of single-Dirac-cone like surface states in which Bi{sub 2}Te{sub 3−x}Se{sub x} with Se/Te-substitution leads to tunable surface states. Our results demonstrate that by fine-tuned MBE growth conditions, Bi{sub 2}Te{sub 3−x}Se{sub x} thin film alloys with tunable topological surface states can be obtained, providing an excellent platform for exploring the novel device applications based on this compound.« less
  • The atomic structure of topological insulators Bi{sub 2}Te{sub 3} thin films on Si (111) substrates grown in van der Waals mode by molecular beam epitaxy has been investigated by in situ scanning tunneling microscopy and scanning transmission electron microscopy. Besides single and multiple quintuple layer (QL) steps, which are typical for the step-flow mode of growth, a number of 0.4 QL steps is observed. We determine that these steps originate from single steps at the substrate surface causing domain boundaries in the Bi{sub 2}Te{sub 3} film. Due to the peculiar structure of these domain boundaries the domains are stable andmore » penetrate throughout the entire film.« less