Laboratory of Magnetism and Magnetic Materials, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
Phys Chem Chem Phys. 2019 Oct 9;21(39):21790-21797. doi: 10.1039/c9cp04719k.
In this paper, the possible electronic phase transitions of β12-borophene crystal are examined using a five-band tight-binding calculation. For different tight-binding models, the Green's function technique is employed for the electronic density of states (DOS). We focus on the modulation of the DOS around the Fermi level with a perpendicular electric field and the dilute charged impurity. The steps to incorporate the effects of external electric field and charged impurity are also detailed with the local Hamiltonian model and the Born approximation, respectively. Our calculations show that the inversion symmetric model is the proper model to discuss the metallic phase of the system, entailing different results compared to the homogeneous model. We find that the electric field opens a tunable band gap and a metal-to-p-doped semiconductor phase transition emerges at the strong perpendicular electric field. The influence of impurity scattering potential on the electronic phase of β12-borophene is much larger than the impurity concentration, in which a metal-to-n-doped semiconductor (metal-to-semimetal) transition takes place at high scattering potentials for the homogeneous (inversion symmetric) model, whereas there is no transition when the impurity concentration is changed. Thereby, producing semimetallic/semiconducting properties by applying an appropriate external electric field and dilute charged impurities paves the way for the realization of β12-borophene-based nano-optoelectronic devices.
本文采用五能带紧束缚计算研究了β12-硼烯晶体可能的电子相变。对于不同的紧束缚模型，采用格林函数技术计算电子态密度（DOS）。我们关注垂直电场和稀带电杂质对费米能级附近 DOS 的调制。还分别使用局域哈密顿模型和玻恩近似详细说明了包含外部电场和带电杂质影响的步骤。我们的计算表明，具有反转对称性的模型是讨论系统金属相的合适模型，与均匀模型相比，得到了不同的结果。我们发现电场会打开可调带隙，并且在强垂直电场下会出现金属到 p 掺杂半导体的相变。杂质散射势对β12-硼烯电子相的影响远大于杂质浓度，对于均匀（反转对称）模型，在高散射势下会发生金属到 n 掺杂半导体（金属到半金属）的转变，而当杂质浓度发生变化时则不会发生转变。因此，通过施加适当的外部电场和稀带电杂质来产生半金属/半导体性质，为实现基于β12-硼烯的纳米光电设备铺平了道路。
