Hydrogenation Of Silicene And Investigation Of Its Electronic Properties

Since the1947, the invention of the transistor in silicon and germanium based semiconductor industry has been rapid development, has greatly improved the life of human beings.The development of the integrated circuit is the most rapid. In order to obtain higher performance and lower energy consumption chip, people continuing to reduce the size of the device and increasing the degree of integration.Hence,on the one hand we need to improvement of device structure to reduce the dimension of the material. On the other hand, The search for new materials. At present, Graphene, molybdenum disulfide, silicene and so on as a novel2D materials and topological insulators have attracted extensive attention. The common characters of these materials are that quasiparticles obey relativistic Dirac equation and the effective mass is zero. This means it is dissipationless in information transmission and is a promising candidate for future devices. Silicene is a new material that resembles most properties of graphene. Due to its rich physics and easy integration into modern semiconductor industry, silicene has attracted tremendous attention from both theorists and experimentalists.In this thesis,we fabricated high-quality silicene using molecular beam epitaxy and hydrogen adsorption was performed by exposing the sample at room temperature to a high-purity H2gas cracked by hot tungsten filament.Then,We use scanning tunneling microscopy systematically studied the structures and electronic properties of the hydrogenation of silicene. The main contents of this thesis are listed as follows:1.We synthesized silicene on Ag(111) using molecular beam epitaxy and studied the structures of hydrogenation, include4×4,(?)×(?),(?)×(?) phase, by scanning tunneling microscopy.2.Combined with first-principles calculations,the structure of hydrogenated silicene can be explained.The hydrogenation of silicene-4x4,which involves7H atoms and rearranged buckling of Si atoms in one unit cell,six are in the same half unit cell and belong to the same sub-lattice,while one in the other half unit cell is in the other sub-lattice.By annealing the hydrogenated silicene to about450K, dehydrogenation occurs. Formtion of a silicene-1×1film from a silicene-(?)×(?) by hydrogenation and indicate silicene-(?)×(?) is not Si-Ag alloy.3.According to the hydrogen absorption capacity and the different substrate temperature the hydrogenation of silicene-(?)×(?) has a lot of different structures.It’s notable that appear complete silicene-1×1and a large number of strip structure when the hydrogen adsorption is saturated.