Design And Simulation Of Two-dimensional Semiconductor Materials With High Carrier Mobility

In 2004,the successful isolation of graphene has totally renewed the conventional cognition that two dimentional (2D) material is physically impossible.Graphene's many exciting properties are bringing revolutions to inorganic 2D material.For example, graphene exhibits extremely high carrier mobility and chemically stable.Therefore, it is a quite promising candidate for future electronic devices. However, the lack of a band gap has greatly hindered the extensive application of graphene in microelectronic devices such as field-effect transistors. In this thesis, we have designed two kinds of inorganic 2D materials and then systematically studied the geometry, electronic structure, mechanic response and carrier mobility of 2D semiconducting materials through density functional theory (DFT) computations.Firstly, we designed the fully hydrogenated stanene, namely SnH, on the basis of monolayer stanene which has been prepared experimentally. SnH is semiconducting with a direct band gap of 1.00 eV, which can be manipulated by external strain.Moreover, the carrier mobility of SnH is much larger than that of MoS2 monolayer.The no appreciable imaginary phonon band structure shows the good kinetic stability of SnH. In contrast, SnH has stronger adsorption in the visible and infrared range of solar spectrum than MoS2 monolayer and is attractive for light harvesting. Therefore,the fantastic properties of SnH render it a promising candidate for microelectronic and optoelectronic devices.In addition, based on having be successfully designed quasi-planar hexacoordinate carbon structure, namely Be2C monolayer, we further studied its electronic properties and the properties of 1D Be2C nanotubes. Be2C monolayer is semiconducting with a moderately tunable direct band gap and has rather strong optical absorption in the ultraviolet region of solar spectrum. Moreover, the carrier mobility of Be2C monolayer is very high. For Be2C nanotubes,they shows good kinetic stability. Moreover, the diameter and chirality of Be2C nanotubes controlling would be effective in adjusting the carrier mobility which would broaden the range of applications in electronic and optoelectronic devices.