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Influence of structure and thermodynamic stability on electronic properties of two-dimensional SiC, SiGe, and GeC alloys

Texto completo
Guilhon, I. [1] ; Teles, L. K. [1] ; Marques, M. [1] ; Pela, R. R. [2, 1, 3] ; Bechstedt, F. [4]
Número total de Autores: 5
Afiliação do(s) autor(es):
[1] Inst Tecnol Aeronaut, Grp Mat Semicond & Nanotecnol, DCTA, BR-12228900 Sao Jose Dos Campos - Brazil
[2] Humboldt Univ, Inst Phys, D-12489 Berlin - Germany
[3] IRIS Adlershof, D-12489 Berlin - Germany
[4] Univ Jena, Inst Festkorpertheorie & Opt, D-07743 Jena - Germany
Número total de Afiliações: 4
Tipo de documento: Artigo Científico
Fonte: Physical Review B; v. 92, n. 7 AUG 24 2015.
Citações Web of Science: 23

The energetics and thermodynamic properties of two-dimensional binary graphene-like alloys made from graphene, silicene, or germanene are investigated by combining first-principles total energy calculations, and a statistical approach to account for disorder and composition effects. For the electronic properties the calculations are performed within the GGA-1/2 approach for an approximate quasiparticle bands. We derive lattice constants, first-neighbor distances, and buckling parameters as a function of composition x. The Si1-xGex system is the only stable random alloy at usual growth temperatures. For Ge1-xCx, we observe strong distortions of the lattice making the random configurations less favorable and leading to a pronounced tendency for phase separation. The situation for Si1-xCx alloys is completely different. An ordered structure with composition x = 0.5 is stable up to T approximate to 1000 K, while intermediate compositions are mainly realized by silicongraphene and graphene or silicene. The ordering and decomposition effects have a strong influence on the average fundamental energy gap versus composition. Whereas large gaps appear for Si1-xCx systems they almost vanish for Ge1-xSix and Ge1-xCx. Moreover, the dependence of the Si1-xCx energy gap on growth temperature is also obtained. The results can be very useful for chemical vapor deposition growth of these materials. (AU)

Processo FAPESP: 12/50738-3 - Estudo de pontos quânticos através de cálculos de primeiros princípios
Beneficiário:Ronaldo Rodrigues Pelá
Linha de fomento: Auxílio à Pesquisa - Regular