Density Functional Theory Study on Energy Band Gap of Armchair Silicene Nanoribbons with Periodic Nanoholes
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Density Functional Theory Study on Energy Band Gap of Armchair Silicene Nanoribbons with Periodic Nanoholes Sadegh Mehdi Aghaei1 and Irene Calizo1,2
1 QUEST Lab, Department of Electrical and Computer Engineering, Florida International University, Miami, Fl 33172, U.S.A. 2 Department of Mechanical and Materials Engineering, Florida International University, Miami, Fl 33172, U.S.A.
ABSTRACT In this study, density functional theory (DFT) is employed to investigate the electronic properties of armchair silicene nanoribbons perforated with periodic nanoholes (ASiNRPNHs). The dangling bonds of armchair silicene nanoribbons (ASiNR) are passivated by mono- (:H) or di-hydrogen (:2H) atoms. Our results show that the ASiNRs can be categorized into three groups based on their width: W = 3P − 1, 3P, and 3P + 1, P is an integer. The band gap value order changes from “EG (3P − 1) < EG (3P) < EG (3P + 1)” to “EG (3P + 1) < EG (3P − 1) < EG (3P)” when edge hydrogenation varies from mono- to di-hydrogenated. The energy band gap values for ASiNRPNHs depend on the nanoribbons width and the repeat periodicity of the nanoholes. The band gap value of ASiNRPNHs is larger than that of pristine ASiNRs when repeat periodicity is even, while it is smaller than that of pristine ASiNRs when repeat periodicity is odd. In general, the value of energy band gap for ASiNRPNHs:2H is larger than that of ASiNRPNHs:H. So a band gap as large as 0.92 eV is achievable with ASiNRPNHs of width 12 and repeat periodicity of 2. Furthermore, creating periodic nanoholes near the edge of the nanoribbons cause a larger band gap due to a strong quantum confinement effect. INTRODUCTION Graphene has earned significant notice due to various noteworthy properties since its discovery in 2004 [1,2]. Motivated by the exceptional properties of graphene, other twodimensional (2D) materials beyond graphene like silicene have drawn enormous attention [3]. Silicon is used widely in semiconductor industry and bears strong resemblance to carbon. The graphene equivalent of silicon, named silicene by Guzmán-Verri and Voon in 2007 [4], exhibits electronic properties similar to graphene and might even challenge it [4]. It was initially explored by Takeda and Shiraishi in 1994 [5], and was synthesized on diverse substrates like Ag (111) [6,7], Ir (111) [8], ZrB2 (0001) [9], and ZrC (111) [10]. The anticipated benefit of silicene over graphene is that it is more compatible with silicon electronics and may be more readily integrated into them. Similar to graphene, silicene does not have a band gap around its Fermi level. However, unlike a flat graphene sheet, a silicene sheet is slightly buckled. The first silicene transistor has been made by Tao et al. [11]. A small band gap of 23.9 meV was created in silicene due to the spin-orbit coupling, which is much higher than that of graphene [11]. To open a band gap in the silicene, several methods have been applied, including by silicene nanoribbons [12], applying a perpendicular electric field to the silicene [13], chemical functionalizatio
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