Novel Phases of Semi-Conducting Silicon Nitride Bilayer: A First-Principle Study [article]

Jiesen Li, Wanxing Lin, Junjun Shi, Feng Zhu, Weiliang Wang, Haiwen Xie, Dao-Xin Yao
2017 arXiv   pre-print
In this paper, we have predicted the stabilities of several two-dimensional phases of silicon nitride, which we name as α-phase, β-phase, and γ-phase, respectively. Both α- and β-phases has formula Si_2N_2, and are consisted of two similar layer of buckled SiN sheet. Similarly, γ-phase is consisted of two puckered SiN sheets. For these phases, the two layers are connected with Si-Si covalent bonds. Transformation between α- and β-phases is difficult because of the high energy barrier. Phonon
more » ... ctra of both α- and β-phase suggest their thermodynamic stabilities, because no phonon mode with imaginary frequency is present. By Contrast, γ-phase is unstable because phonon modes with imaginary frequencies are found along Γ-Y path in the Brilliouin zone. Both α- and β-phase are semiconductor with narrow fundamental indirect band gap of 1.7eV and 1.9eV, respectively. As expected, only s and p orbitals in the outermost shells contribute the band structures. The p_z orbitals have greater contribution near the Fermi level. These materials can easily exfoliate to form 2D structures, and may have potential electronic applications.
arXiv:1707.02819v1 fatcat:vryx77f3vbec3nappprjord7cm