Layer dependent electronic and optical properties of Silicane, Germanane and Stanane.*

The successful isolation of graphene by Geim and Novoselov, totally changed our minds. Folowed by graphene, new 2D structures were studied e.g. hexagonal boron nitride (h-BN), transition metal dichalcogenides (TMDC), black and blue phosphorus, among others. Looking into the periodic table, in the same column of carbon, we can find silicon, germanium and tin. Unlike carbon, these other group-IV elements do not have a layered structure similar to graphite. Their monolayer structures are obtained if grown on metallic substrates. Recently, the successful manufacture of fully hydrogenated germanene, the hydrogenation of silicene on Ag(111) and formation of half-silicane were reported. Such achievements bring new opportunities for the applications of 2D structures of group IV in nanoelectronics. In this work, by means of the state-of-the-art in first principles calculations, we study the electronic and optical properties of hydrogenated group IV - Silicane, Germanane and Stanane. We show that it is possible to control the energy gap of the systems through the number of layers. Moreover, we accurately determined the alignment of the energy levels (band offsets) for all the structures.