LAUSR

Abstract The compatibility of silicene with the semiconductor technology and its promise in thermoelectric and in optoelectronic devices demands modulation and optimization of its thermal and optical properties using structural modifications. Here we investigate the thermal and optical properties of silicene supported group IV honeycomb bilayer and heterobilayer nanoribbon structures (silicene/germanene and silicene/graphene) using molecular dynamics simulation and first principle calculations. Our modeled silicene/germanene nanoribbons show ~43% lower room temperature average thermal conductivity (2.94 W/m/K) compared to that of similar sized silicene nanoribbons (5.1 W/m/K). Similarly, in silicene/graphene nanoribbons, heterostructuring results in a ~25× reduction of the in-plane thermal conductivity compared to that of a graphene nanoribbon, which is attributed to the phonon confinement in the low frequency region and large mismatch in the phonon frequencies between the monolayers of these heterostructures (~50 THz for the graphene layer and ~11 THz for the silicene layer in the silicene/graphene nanoribbons). We also characterize the temperature and the size dependent thermal conductivity of the modeled structures. The realized low thermal conductivity in these heterostructures could lead to the design of optimized thermoelectrics. Furthermore, we compute the frequency dependent dielectric function and show that the absorption coefficients of our modeled nanostructures are 1.5× to 2× large compared to those of silicene monolayer in the ultraviolet (UV) region, which could be useful in optoelectronic devices such as UV photodetectors. Thus, heterostructuring could be an encouraging route to tune the thermal and optical properties of silicene nanostructures for next generation nano-electronic and optoelectronic devices.