Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 26: Two-Dimensional Materials III (joint session DS, HL, TT, organized by HL)

TT 26.3: Vortrag

Dienstag, 21. März 2017, 10:00–10:15, POT 51

Phase separation and composition fluctuation effects on electronic and optical properties of (BN)_1−x(C₂)_x 2D alloy — •Ivan Guilhon¹, Lara K Teles¹, Marcelo Marques¹, and Friedhelm Bechstedt² — ¹Grupo de Materiais Semicondutores e Nanotecnologia, Instituto Tecnológico de Aeronáutica, DCTA, 12228-900 São José dos Campos, Brazil — ²Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, D-07743 Jena, Germany

(BN)_1−x(C₂)_x alloys are promising materials for band gap engineering in two-dimensional electronics. Despite the importance of microstructural features, such as phase separation and composition fluctuation. The current theoretical studies of such monolayer alloys are often restricted to investigate “guessed" nonrandom structures.

Using DFT calculations combined with a statistical approach to account for disorder effects, we study the properties of these 2D alloys as a function of their average composition. A complete scenario of how thermodynamic conditions affect the distribution of atoms is provided. The solubility limits and critical temperature are studied by constructing a T-x phase diagram.

In this context, we calculate the energy gap as a function of the composition and optical absorbance spectra are predicted for different compositions. Our predictions are compared with the experimental findings. We reproduce the experimentally found absorption spectra with a two-peak pattern for intermediate carbon concentrations and identify them with phase-segregated instead of homogeneous alloys.