Rita John
University of Madras, India
Title: Theoretical investigation on 2D materials: graphene, silicene, germanene, and stanene
Biography
Biography: Rita John
Abstract
Silicene, germanene, and tin; the 2D analogues of graphene are structurally different from graphene due to the buckling distorsions in the lattice. Hybridization in graphene is purely sp2. It is sp2/sp3 mixed orbitals in other 2D structures that results in buckling and causes pronouced effects in their properties. Structural, electronic, optical and mechanical properties are investigated. Density Functional Theory with Generalized Gradient Approximation as implemented in CASTEP is used. At the Dirac point, the dispersion curve is linear in graphene and quadratic in all other materials. Critical points, saddle points, Van Hove singularities are investigated in band structures and density of states histograms. Optical properties unveil the frequency dependence and non linear response of absorption. Graphene exhibits prominent aborption in the ultraviolet region and shifts towards the infrared region in all other 2D structures. Intensity of absorption increases in layered structures. Birefringence is exhibited by single and layered structures. Real part of refractive index establishes the anisotropic behaviour. Bilayer exhibits semimetallic behaviour. Trilayer portrays metallic nature. Study on mechanical properties brings out the unique stiffness of graphene. Bonding characteristics and charge density contours endorse that covalency reduces from graphene to stanene, due to which elastic moduli decreases from graphene to stanene. Poisson’s ratio shows increased brittleness in graphene, semimetallic nature in silicene and germanene, and metallic nature in stanene. Although silicene, germanene, and stanene posses only 20%, 14%, and 9% of Young’s modulus, the bonding nature facilitates its suitability in semiconductor industry along with substrates to enhance the conduction mechanism.