Hydrogenation of Two-dimensional group-IV Xene

Abstract

Density fl1l1 ctionni thcory calcula tions nrc used to study the structural and electronic properties of two-d imensional group-IV monolayer Xcncs (X=C, Si, Ge, Sn, Pb). T he lattice constant a and bonel length I of bulk X increase from C to Ph. In monolayer Xcncs, the buckling 0 incrcflses from C to Pb. Graphcnc has no band gnp due to absell ce of Px/Py states at the Dirnc cone. As one moves down the group-IV, P:e/Pv electrons increu,':iC their contri bution whi ch results in increasing the band gap due to spin-orbit coupling (SOC). J-Iybridizfl.Lion changes from 5p2 (graphenc) to sJ}-l ikc (pillmbcnc). Partially hydrogenation of Xenos increases 0, a & l [IS compnrcd with the pristine casco Hydrogenation also diminishes the Dirac cone in Xenes. T he spin-polari'l.cd calculations reveal fI. mftgnetic moment of l.O/LO, and Xenes appear as magnetic semiconductors. The SOC splits the two-fold degenera te stntes into non-degenerate states, with a spliLt.ing gap 2 mcV (grnphene) to ~ meV (plulllbene). In full hydro genation of the Xencs, the lattice constants flOd bond lengths turn out to be even larger flS compared to semi-hydrogenated cflse and the resulting planar structure is S p2 hybridized. Moreover, t he band gap is found to be larger than semi-hydrogenated and pristine cases and no spin-polnrir,cd states are seen. Fu1J hydrogenation washout the buckling in Xencs. SOC opens a band gap of 0.4 7 eV in fully-hydrogenated pll1lnbcne, which is otherwise gap-less material