Fully and partially iodinated germanane as a platform for the observation of the quantum spin Hall effect

Abstract

Motivated by the recent isolation of the trivial insulator germanane, a fully hydrogenated germanene, we show that partially substituting hydrogen atoms with iodine on only one side of the material creates a two-dimensional topological insulator with a large band gap of 0.49 eV. This functionalization opens up different routes for the observation of the quantum spin Hall effect in fully two-dimensional materials. We also show that by creating nanoroads with the pattern functionalization of germanane by iodine in an ordered or disordered way, topologically protected interfaces states arise at the boundary of germanane/iodinated germanane.