24Silicene is emerging as a two-dimensional material with very attractive electronic properties for a 25 wide range of applications; it is a particularly promising material for nano-electronics in silicon-26 based technology. Over the last decade, the existence and stability of silicene has been the subject 27 of much debate. Theoretical studies were the first to predict a puckered honeycomb structure with 28 electronic properties resembling those of graphene. Though these studies were for free-standing 29 silicene, experimental fabrication of silicene has been achieved so far only through epitaxial 30 growth on crystalline surfaces. Indeed, it was only in 2010 that researchers presented the first 31 experimental evidence of the formation of silicene on Ag(110) and Ag (111), which has launched 32 silicene in a similar way to graphene. This very active field has naturally led to the recent growth 33 of silicene on Ir(111), ZrB 2 (0001) and Au(110) substrates. However, the electronic properties of 34 epitaxially grown silicene on metal surfaces are influenced by the strong silicene-metal 35 interactions. This has prompted experimental studies of the growth of multi-layer silicene, though 36 the nature of its "silicene" structure remains questionable. Of course, like graphene, synthesizing 37 free-standing silicene represents the ultimate challenge. A first step towards this has been 38 reported recently through chemical exfoliation from calcium disilicide (CaSi 2 ). In this review, we 39 discuss the experimental and theoretical studies of silicene performed to date. Special attention is 40 given to different experimental studies of the electronic properties of silicene on metal substrates. 41New avenues for the growth of silicene on other substrates with different chemical characteristics 42 are presented along with foreseeable applications such as nano-devices and novel batteries. 43 44 45 46 47 111In this review paper, we will present the current state of the art of silicene. We will present new 112 avenues for the growth of silicene along with foreseeable potential applications of silicene. 113 2-Silicene growth on Ag(110) 114 6 2.1 Formation of Silicene nanoribbons on the clean Ag(110) 115 A sub-monolayer deposition of silicon on Ag(110) at room temperature (RT) results in the 116 formation of one-dimensional silicene structures [38]. The STM images clearly show isolated 117 ribbons all oriented along the (-110) direction [38-40]. It is remarkable to observe that the ribbons 118 all have exactly the same width of 1.6 nm as shown in Figs. 2.1(a) and (b). The higher resolution 119 STM image in Fig. 2.1(b) shows that the isolated Si nanoribbons (NRs) have an internal structure 120 composed of six-atom blocks aligned along the nanowires. Each block has the form of a square 121 joined to a parallelogram with a ridged profile (Fig. 2.1c). From a visual inspection of the STM 122 images, a hexagonal structure is not visible. In fact, DFT structure calculations were necessary to 123 reveal the hexagonal structure of ...

No abstract