An array of layers in silicon sulfides: Chainlike and monolayer

While much is known about isoelectronic materials related to carbon nanostructures, such as boron-nitride layers and nanotubes, rather less is known about equivalent silicon-based materials. Following the recent discovery of phosphorene, here we discuss isoelectronic silicon-monosulfide monolayers. We describe a set of anisotropic structures that clearly have a high stability with respect to previously reported silicon-monosulfide monolayers. The source of the layer anisotropy is related to the presence of Si-S double chains linked by some Si-Si covalent bonds together with a remarkable spd hybridization on Si. The increased stability is related to silicon forming four bonds, including an additional double-bond-like Si-Si bond. The involvement of d orbitals brings more variety to silicon-sulfide-based nanostructures that are isoelectronic to phosphorene, which could be relevant for future applications, adding extra degrees of freedom.This work has been partially supported by the Projects No. FIS2013-48286-C2-1-P and No. FIS2016-76617-P of the Spanish Ministry of Economy and Competitiveness MINECO, the Basque Government under the ETORTEK Program 2014 (nanoGUNE2014), and the University of the Basque Country (Grant No. IT-366-07). T.A.-L. acknowledges the grant of the MPC Material Physics Center - San Sebastian. F.A.-G. acknowledges the DIPC for their generous hospitality. We also want to acknowledge the DIPC computer center (T.A.L., A.A., and F.A.-G.).Peer reviewe