Strain tunable bandgap of silicene on monolayer gallium phosphate

Abstract

Possibility of band gap in zero-gap silicene having linear dispersion and massless fermions has been a critical issue for it applications in nanoelectronics particularly with lowered carrier mobility trade off. In this thesis, we analytically explore the effects of symmetry (stacking order) on material properties by applying homogenous biaxial strain. We conduct theoretical studies on silicene/hexagonal-GaP hetero-bilayer (Si/h-GaP HBL) opening a band gap (0.31 eV) which varies with stacking order and interlayer spacing. Using the framework of density functional theory (DFT) with the Perdew-Burke-Ernzerhof (PBE) non-polarized Generalized Gradient Approximation (GGA) exchange-correlation functional, we perceive that mechanically adjustable band gap and quasi-particle effective mass (m*) are realizable in Si/GaP HBL by application of in-plane homogenous biaxial strain. Moreover, a detailed speculation of the relationship between strain-engineered band gap of Si/GaP HBL and fermi velocity of charge carriers have also been expounded. These should affect the carrier mobility and conductivity eventually leading to applications of Si/h-GaP in silicene based devices. Finally, utilizing our understanding on strain-engineered band gap, we have proposed a new device consisting on Si/h-GaP HBL as the channel material.