Simulation Of Single Layer MoS₂ Doping Based On Energy Band Control

Molybdenum disulfide?MoS₂?is a new two-dimensional layered structure of nano materials which is similar to that of graphene,but different from zero band gap properties of graphene,which itself has a band gap width of semiconductor material is natural,which makes it more outstanding physical and chemical properties.It has been widely used in solid lubricants,batteries,cathode materials,field effect transistors,molecular sensors and photodetectors,and has become one of the most popular semiconductor materials.However,in practice,semiconductor materials can not be applied directly,it is necessary to control their band gap and edge potential so as to meet the requirements of different applications of electrical properties.based on the above reasons to carry out the simulation of single Mo S₂ electronic band control research.In the research work,we have used two kinds of commonly used band modulation methods-doping control and vacancy defect regulation,respectively,to simulate the band structure of single layer MoS₂:?1?Based on the first principles DFT method,the effects of Se doping on the electronic band of single layer MoS₂ were investigated,and the effects of doping on the photocatalytic properties were also discussed.The results show that the single layer MoS₂ has a band gap of 1.740 eV,and its high symmetry points are in the Brillouin zone K,the band structure is the direct band gap.Se doping appropriate concentration calculation results show that the doping of MoS₂ single band gap width is not much affected,but the analysis of the band edge potential,the bottom of the conduction band and valence band potential appeared smaller synchronous down,just balance its application in the photocatalytic decomposition of water oxidation and reduction reaction efficiency.In addition,it is found that the formation of Se doped system is low and the thermodynamic performance is stable,and it is proved that the doping of Se element is easy to realize.?2?Based on the first principles DFT method,the effects of Nb doping on the electronic band of single layer MoS₂ were investigated,and the effects of doping on the semiconductor devices were also discussed.The results show that the band gap decreases with Nb doping,and decreases with the increase of the concentration.Through the analysis of the different concentration of doping density of States found that Nb doping makes the bottom layer MoS₂ conduction band move to the left,and the higher the concentration of moving more and more,and the top of the valence band small changes,resulting in the band gap value greatly reduced,will make it the current switch of electronic conduction band ratio,the performance will be obtained significantly improved.In addition,it is found that the formation of Nb doped system can be reduced by the formation energy calculation.?3?Based on the first principles DFT method,the effects of 3 kinds of vacancy defects(V_S,V_Mo,V_MoS6)on the electronic band structure of single layer MoS₂ were investigated.The calculated results show that the vacancy defects can cause the lattice distortion around them,and the S-Mo-S bond angles near the defects are relatively reduced.The results of the band calculations show that the 3 vacancy defects introduce a new defect energy level in the MoS₂ band gap,which makes the band gap decrease greatly.The defect energy level of VS vacancy is located in the center of the band gap,and the defect energy levels of V_Mo and V_MoS6 vacancies are close to the top of the valence band,but do not cross the Fermi level.In addition,by comparing the results of the density of States,it is found that the vacancy defects on the single layer MoS₂ can be controlled mainly by the change of the conduction band bottom,but little on the valence band.