Analysis of Structural Electronic and Vibrational Properties of Two Dimensional Silicon Carbide

Abstract

Two dimensional silicon carbide (2D-SiC) has fascinated incredible research attention recently because of its large direct bandgap and high exciton binding energy. Nonetheless, no well-established researches have been performed on 2D-SiC combining its physical, electronic and vibrational properties. Here, we have investigated the details of the full physical picture of novel 2D-SiC describing their structures and functions as well as the electronic tunability and phonon properties using the first principle density functional theory. The structural properties show that 2D-SiC has the honeycomb graphene like structure with lattice constant 5.72 Ry (3.101 A). The positive phonon modes in the vibrational properties indicate that the plane structure of 2D-SiC is dynamically stable. The calculated projected density of states (PDOSs) have exposed that the conduction and valence band edges at the K point have been constructed by the π and π*-bands, which are formed due to the bonding and anti-bonding combination of Si-3pz and C-2pz orbitals.

The electronic properties of semiconductor materials are greatly influenced by the spin orbit coupling (SOC) effect. The effects of SOC on the electronic structure of 2D-SiC have been studied using the first-principle calculation which is implemented on quantum espresso 6.1 version. Though the electronic band structure shows that the 2D-SiC monolayer possesses a direct band gap of 2.71 eV, the electronic band become split and the band gap turns to 2.827 eV while considering the SOC effect. It is found that SOC induces splitting in both valence and conduction bands of this material. A SOC induced bandgap on the order of 117 meV has been generated at the K-point. The calculated partial electron density of state exposes that the silicon 3p electrons and carbon 2p electrons are critical in forming the electronic bandgap. Phonon density of states, thermal properties, Raman and Infrared spectra of this material have been also calculated. In addition, the effect of Si and C vacancies on the electronic properties of 2D-SiC has been addressed with and without considering SOC effect. These findings suggest that the monolayer 2D-SiC may present a new platform of 2D materials, with a rich variety of properties for applications in electronics, optoelectronics and spintronics devices.