Abstract

Graphene, a two-dimensional (2D) material with a honeycomb structure, exhibits some extraordinary physical properties and can, in principle, be considered as an elementary building block for all carbon allotropes (Lin et al. 2008). Developments in the science of graphene prompted an unprecedented surge of activity and demonstration of new physical phenomena. Despite its success, graphene still faces some severe problems in its nature of a semimetal or zero band gap semiconductor and its incompatibility with the current Si-based technology (Han et al. 2007). Given that the honeycomb geometry is related to some of the exceptional properties of graphene, there is strong motivation to investigate its analog, 2D Si, or silicene (Vogt et al. 2012). Silicene, exhibiting many superior properties such as a modulable gap due to the asymmetric structure, can solve the above problems smoothly and thus has received intense interest (Ni et al. 2011; Drummond et al. 2012). Given the fact that thermal transport plays a critical role in many applications such as heat dissipation in nanoelectronics and heat prohibition in thermoelectric (TE) energy conversion, there has been an emerging demand in characterizing the thermal (mainly phonon) transport property of silicene. Moreover, research results have shown that silicene exhibits a few novel thermal transport properties, which are fundamentally different from that of graphene, despite the similarity of their honeycomb lattice structure (Pei et al. 2013; Gu and Yang 2015; Xie et al. 2016). Therefore, the anomalous physical properties, primarily stemming from its unique low-buckled structure, may enable silicene to open entirely new possibilities for revolutionary electronic devices and energy conversion materials.