Optical absorbance and band-gap engineering of (BN)1x(C2)x two-dimensional alloys: Phase separation and composition fluctuation effects

I. Guilhon, M. Marques, L. K. Teles, and F. Bechstedt
Phys. Rev. B 95, 035407 – Published 10 January 2017

Abstract

The (BN)1x(C2)x alloys are promising materials for band-gap engineering in two-dimensional electronics. In this work, we provide a complete scenario of statistical possibilities for the distribution of atoms and its influence on electronic and optical properties. Using first-principles calculations combined with the generalized quasichemical approximation to account for disorder effects, we study the properties of these two-dimensional alloys as a function of their average composition. Our results show that atomic arrangements with C-C and B-N bonds are energetically favored over the ones with B-B and N-N bonds, explaining the known tendency to phase separation, verified by a Tx phase diagram. We calculate the energy gap as a function of the composition considering both composition fluctuation and phase separation effects. Experimental data are discussed in this context. Finally, we obtain absorption spectra reproducing a two-peak pattern for intermediate carbon concentrations found experimentally and identified with phase-segregated instead of homogeneous alloys.

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  • Received 1 August 2016
  • Revised 3 November 2016

DOI:https://doi.org/10.1103/PhysRevB.95.035407

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

I. Guilhon*, M. Marques, and L. K. Teles

  • Grupo de Materiais Semicondutores e Nanotecnologia, Instituto Tecnológico de Aeronáutica, DCTA, 12228-900 São José dos Campos, Brazil

F. Bechstedt

  • Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, D-07743 Jena, Germany

  • *ivanguilhonn@gmail.com
  • mmarques@ita.br
  • lkteles@ita.br

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Issue

Vol. 95, Iss. 3 — 15 January 2017

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