Theoretical Study On The Performance Regulation Of Low-dimensional Semiconductor Nanomaterials

With the development of nanotechnology,low-dimensional semiconductor nanomaterials will be really important in our life in the future.Low-dimensional semiconductor nanomaterials have unique optical,electrical,magnetic and chemical properties,which are quite different from their corresponding bulk one.Low-dimensional semiconductor nanomaterials can be widely used in nano-photonics and nano-electronics fields,if tuning their properties by appropriate way.Thus,it is important to control the structure,understand the link between structure and unique properties of low-dimensional functional nanomaterials.In order to find out controllable way to tune the properties of low-dimensional semiconductor nanomaterials,we have studied cadmium selenide nanowires,cadmium selenide nanoribbons and puckered monolayer arsenene by using molecular dynamics simulation and first-principles density functional theory simulation.These results will provide some helpful information to the application of low-dimensional semiconductor nanomaterials.The main contents and results are presented as following:(a)We study the strain dependence on the electronic and optical properties of cadmium selenide nanowires by first-principles density functional theory simulation.Simulation results show that an interesting band-switch behavior occurs at the valence bands regardless of size.(b)We study the thermal transport in cadmium selenide nanowires by using nonequilibrium molecular dynamics simulations.The results show that the compressive strain can tuning the thermal conductivity efficiently.(c)We study bandgap tuning in armchair cadmium selenide nanoribbon by using first-principles density functional theory simulation.We have applied transverse electric fields in the monolayer ribbons,the bandgap decrease with increasing transverse electric field and closes at a critical field strength which leads to the transition of metal.It shows that the critical strength decreases as ribbon width increases.(d)We study the mechanical and optical properties of the puckered monolayer arsenene under the uniaxial lateral strain by using first-principles density functional theory simulation.We obtained a positive linear Poisson's ratio in both x and y directions.However,the puckered monolayer arsenene shows a negative Poisson's ratio of-0.080 in the out-of-plane direction under the in-plane strain along the zigzag direction,larger than that of the two-dimensional black phosphorus.And the dielectric function show different behavior under strain along different directions.