Elasticity, piezoelectricity, and mobility in two-dimensional BiTeI from a first-principles study

Through first-principle calculations, we investigate the stability, electronic structures, elasticity, piezoelectricity, and mobility of 2D BiTeI monolayer. Our calculations show that 2D BiTeI monolayer is energetically, mechanically, thermodynamically, and dynamically stable. In addition to its well-known large Rashba spin-splitting, the monolayer exhibits a high-tensile ductility and mechanical flexibility. Formation of BiTeI/BN van der Waals heterostructure makes it freestanding without perturbing the electronic structure. The broken mirror symmetry structure induces out-of-plane internal electric field of 0.289 eV angstrom(-1), yielding out-of-plane piezoelectric coefficients of 0.556 pm V-1, which is larger than that of Janus group III and transition metal chalcogenide monolayers. Furthermore, the effective masses and mobility of electrons are 0.176 m(e) and 392 cm(2) V-1 s(-1), respectively, which are half and six times of those of the MoS2 monolayer, respectively. These charateristics make 2D BiTeI a potential candidate for a wide variety of applications in nanoscale spin and electromechanical devices.