High quality SnS van der Waals Epitaxies on graphene buffer layer

摘要

We report investigation of SnS van der Waals epitaxies (vdWEs) grown by molecular beam epitaxy (MBE) technique.Experimental results demonstrate an indirect bandgap of ~1 eV and a direct bandgap of ~1.25 eV. Substantialimprovement in the crystallinity for the SnS thin films is accomplished by using graphene as the buffer layer. Using thisnovel growth technique we observed significant lowering in the rocking curve FWHM of the SnS films. Crystallite sizein the range of 2-3 μm is observed which represents a significant improvement over the existing results. The absorption coefficient, α, is found to be of the order of 10sup4/sup cmsup-1/sup which demonstrates sharp cutoff as a function of energy for films grown using graphene buffer layers indicating low concentration of localized states in the bandgap. Hole mobility as high as 81 cmsup2/supVsup-1/supssup-1/sup is observed for SnS films on graphene/GaAs(100) substrates. The improvements in the physical properties of the films are attributed to the unique layered structure and chemically saturated bonds at the SnS/graphene interface. As a result, the interaction between the SnS thin films and the graphene buffer layer is dominated by a weak vdW force and structural defects at the interface, such as dangling bonds or dislocations, are substantially reduced.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.