PC-silicene: A two-dimensional silicene allotrope with strong anisotropic conductance

Department of Applied Physics, Nanjing University of Science and Technology - Nanjing 210094, China

^(a) qianyan@njust.edu.cn
^(b) mrhpwu@njust.edu.cn (corresponding author)

Received: 29 April 2021
Accepted: 9 June 2021

Abstract

Among the reported two-dimensional silicon materials, only hexagonal and kagome-like silicene have been reported experimentally. Thus, designing such materials with another strategy is desirable. Based on the experimentally synthesized pentagonal silicon cluster recently and via a swarm structure search method, herein we report a two-dimensional silicene allotrope by combining pentagonal silicon clusters. Further calculations show that this silicene allotrope exhibits great anisotropic conductance, it behaves as a metal with linear energy dispersions along the b -direction and Dirac point located at about 0.10 eV below the Fermi energy level, while it exhibits semiconducting state along the a -direction. This strong anisotropic conductance is driven by the different coordination numbers of silicon atoms. Through hydrogenating the three-fold coordinated silicon atoms, the silicene allotrope would turn into a semiconductor with a direct band gap of 1.60 eV (2.05 eV under HSE level). Particularly, the hydrogenated model possesses high carrier mobility of and at room temperature for electrons and holes, respectively. This finding promotes potential applications of silicon nanomaterials in in-plane anisotropic nanoelectronic, high-speed electronic, and photovoltaic devices.