Structural disorder of natural BimSen superlattices grown by molecular beam epitaxy

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F18%3A10379316" target="_blank" >RIV/00216208:11320/18:10379316 - isvavai.cz</a>

Alternative codes found

RIV/00216224:14310/18:00104790

Result on the web

<a href="https://doi.org/10.1103/PhysRevMaterials.2.054202" target="_blank" >https://doi.org/10.1103/PhysRevMaterials.2.054202</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevMaterials.2.054202" target="_blank" >10.1103/PhysRevMaterials.2.054202</a>

Result language

angličtina

Original language name

Structural disorder of natural BimSen superlattices grown by molecular beam epitaxy

Original language description

The structure and morphology of BimSen epitaxial layers with compositions ranging from Bi2Se3 to the Bi1Se1 grown by molecular beam epitaxy with different flux compositions are investigated by transmission electron microscopy, high-resolution x-ray diffraction, and atomic force microscopy. It is shown that the lattice structure changes significantly as a function of the beam flux composition, i.e., Se/BiSe flux ratio that determines the stoichiometry of the layers. A perfect Bi2Se3 phase is formed only with a sufficiently high additional Se flux, whereas Bi1Se1 is obtained when only a BiSe compound source without additional Se is used. For intermediate values of the excess Se flux during growth, Bi2Se3-delta layers are obtained with the Se deficit delta varying between 0 and 1. This Se deficit is accommodated by incorporation of additional Bi-Bi double layers into the Bi2Se3 structure that otherwise exclusively consists of Se-Bi-Se-Bi-Se quintuple layers. While a periodic insertion of such Bi double layers would result in the formation of natural BimSen superlattices, we find that this Bi double-layer insertion is rather stochastic with a high degree of disorder depending on the film composition. Therefore, the structure of such epilayers is better described by a one-dimensional paracrystal model, consisting of disordered sequences of quintuple and double layers rather than by strictly periodic natural superlattices. From detailed analysis of the x-ray diffraction data, we determine the dependence of the lattice parameters a and c and distances of the individual (0001) planes d(j) as a function of composition, evidencing that only the in-plane lattice parameter a shows a linear dependence on composition. The simulation of the diffraction curves with the random stacking paracrystal model yields an excellent agreement with the experimental data and it brings quantitative information on the randomness of the stacking sequence, which is compared to growth modeling using Monte Carlo simulations. The analysis of transmission electron microscopy data furthermore confirms that the Bi-Bi bilayers contain a large amount of vacancies of up to 25%. Conductivity and Hall data confirm that BimSen phases containing Bi-Bi double layers exhibit a rather semimetallic behavior.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Project

<a href="/en/project/EF15_003%2F0000485" target="_blank" >EF15_003/0000485: Nanomaterials centre for advanced applications</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Physical Review Materials

ISSN

2475-9953

e-ISSN

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Volume of the periodical

2

Issue of the periodical within the volume

5

Country of publishing house

US - UNITED STATES

Number of pages

14

Pages from-to

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UT code for WoS article

000433005500002

EID of the result in the Scopus database

2-s2.0-85056774591