First-principles Tuning The Schottky Barrier Heights In Metal And Semiconductor Heterojunction

Since the graphene won the Nobel Prize for physics in 2010,scientists and industry began fanatical pursuit of graphene.It's different from the graphite,graphene is only a carbon atom layer thickness,own excellent properties,such as mechanical and electrical properties.We're going after graphene at the same time,a large number of two-dimensional materials have also been successively developed,from the point of the periodic table,these elements mainly includes:the transition metal,carbon group elements,sulfur and other elements.These thin two-dimensional material have new properties that are very different from bulk material.Generally speaking,the two-dimensional layer thickness of material is made up of one or a few atoms of covalent bond of the lattice.They surface is very clean and tidy,no dangling bond,not plagued by the surface defect mode.In addition,because 2 d layered materials is usually connected by.Van der waal.Van der waal's interaction allows different material of two kinds of consolidation and not restricted by the crystal lattice mismatch.A variety of nanoscale two-dimensional layered materials can be integrated by van der waal,and create new properties.Research on 2 d heterojunction interface electronic properties become meaningful.This article is based on density functional theory using the first principles method to study the different 2d interface properties of the semiconductor and metal heterojunction.This paper studies the interface of the schottky barrier height.To obtain the main innovative results are as follows:1 The structures and electronic properties of Pd-MoS2 contact are investigated.The height of Schottky barrier for Pd-MoS2 contact can be tuned by different strains.Our results show that the contact nature is n-type Schottky barrier and the barrier height can be decreased to zero under the increased tensile strain(6%).By analyzing the orbitals of MoS2 near band gaps and charge distribution,we find that the Schottky barrier heights is determined by the Mo dz2,orbits in the Pd-MoS2 contact.2 The structures and electronic properties of phosphorene and graphene heterostructure are investigated.The phosphorene and graphene heterostructure Schottky contacts can be tuned from p-type to n-type via the-2%to-4%in-plane strains.After the band structure and density of states of P atoms orbitals are analyzed,we find that the P-pz orbitals determine the Schottky barrier height(SBH).3 The electronic properties of MoS2 and graphene heterostructure are investigated.The Schottky doping for MoS2 and Graphene contact can be tuned by the interfacial distance.Our calculations show that the Schottky doping can be transformed from an n-type Schottky contact to p-type Schottky contact when the interfacial distance decreased.We find that interfacial charge transfer and the Fermi level shift determines the Schottky barrier transition from n-type Schottky contact to p-type Schottky contact.4 First-principles calculation is used to study the interfacial properties of the SrRuO3/MoS2 heterojunction.It is found that the huge magnetic moments in of monolayer MoS2 largely originate from the Ru-S hybridization for the Ru-terminated interface.Moreover,for the SrO-terminated interface,the calculated results show that the Schottky barrier height can be significantly reduced to zero for the SrO-terminated interface.5 The novel metal-insulator-semiconductor(MIS)diode consisting of graphene,hexagonal boron nitride(hBN),and monolayer MoS2 are investigated.The interfacial Schottky barrier height(SBH)can be tuned by the thickness of hBN layer.In addition,we study the influence of epitaxial electric field to interfacial properties of GBM heterostructure,comparing with GM heterostructure.The result shows that,after inserting hBN layers,the GBM heterostructure have better rectifier features than GM heterostructure.