Research On Modulating Electronic Structure Of Novel Two Dimensional Materials

Nanoscale electronic device has become one of the indispensable parts of today’s society. The development of nanoscale electronic device directly affects the level of people’s life. Thus, people hope to design the nano electronic device with miniaturization, facilitation, integration and functionalization. It is well known that nano electronic device was composed of nano materials. Therefore, properties of nano materials directly decide the performance of nano electronic device. In this article, using first principle calculations, we modulated properties of novel two dimensional nano materials. We hope to find the internal mechanism and obtain the universal rule for modulating the properties of novel two dimensional materials. We believe these studies will improve the characteristics of two dimensional nanomaterials, and play a important role for improving the performance of two dimensional nano electronic device. The main results are as follow:1. A systematic study has been carried out to investigate the structure and electronic property of Si-substituted graphene. We found that Si-substitution would destroy the structure of graphene and affect the band gap of graphene. With the increase of Si consistency, the band gap of graphene increases, realizing the modulation of the band gap of graphene. To utilize such a substitution-induced band gap change, we proposed a theoretical design for fabricating quantum well device. If the substitutional region is sufficiently large, the quantum well structure with defined gaps is very stable. The stable quantum well structure can be used to the field of light emitting.2. A systematic study has been carried out to investigate the structure and electronic property of metal atom-substituted BN. We found that geometric structure and stability strongly relates with types of substituted atom and substituted structure. Metal atom-substituted BN can display many different physical phenomena. Substituted metal atom not only can lead BN to be a magnetic material but also can change the band gap of BN. Therefore, through the substitution of different metal atoms, we can control the electronic structure of BN, leading it to be used at many new fields.3. A systematic study has been carried out to investigate the structure and electronic property of MoS2 with vacancy defects. We found that zigzag vacancy cluster can effectively induce and control the magnetic state of MoS2. Triangular zigzag vacancy cluster can make MoS2 display ferromagnetic characteristic, rectangular and circular zigzag vacancy cluster can make MoS2 display antiferromagnetic characteristic. Note that we can control magnetic moments, coupling of magnetic states and stability of magnetic states by adjusting structure of vacancy cluster, distance between vacancy clusters and the size of vacancy cluster.4. A systematic study has been carried out to investigate the structure and electronic property of germanane with vacancy defects. We obtained two mainly results. Firstly, magnetic states of germanane can be effectively induced and controlled by changing the type of H-vacancy cluster. With the increase of size of H-vacancy cluster, the magnetic moment of germanane increases. This result plays an important role for the application of germanane in magnetic devices. Second, the distribution of space charge of germanane can be effectively controlled by changing the type of H-vacancy cluster. This result plays an important role for the application of germanane in photoelectron devices.5. A systematic study has been carried out to investigate the structure and electronic property of graphene positioned on ZnO surface. We found that there is a weak interaction between grapnene and ZnO surface, which destroys the symmetry of graphene and makes graphene create a weak band gap. On one hand, when the distance between the graphene and ZnO decreases, the band gap of graphene increases. On the other hand, when the distance between the graphene and ZnO decreases, the electron effective mass of graphene increases. Thus, based on such two results, we believe that there ia a compensative relationship between the electron effective mass of graphene and band gap of graphene.However, after fitting electron transfer rate, we found that that the electron transfer rate of graphene is about 0.94×106 m/s, which is very high. So, such high electron transfer rate and certain band gap make graphene become an ideal material of the transistors.6. A systematic study has been carried out to investigate the structure and electronic property of BN positioned on Co(111) surface. We found that, there is a certain interaction between BN and Co(111) surface, which makes BN present magnetism. Further study shows that the magnetism of BN mainly comes from σ states located at the fermi level, and the spin polarization at the fermi level arrives at 90%. Such high spin polarization ensures a transmission of single spintronic electrons, leading the BN to be effectively applied at the field of spin transport.