Manifestation of interface-induced effects of two-dimensional MSi2/Si(111) quantum heterostructures: A first principles study

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Metal/semiconductor (M/S) heterojunctions play key role in the materials physics as well as electronic device applications. This is because of several interface-induced properties like formation of Schottky barrier height (SBH), Fermi level pinning, evolution of metal-induced gap states (MIGS) etc. The overall device performance crucially depends on the electronic structure as well as the geometry of the interface. The transition metal disilicides (MSi 2 ) are essential parts of the silicon-based devices. MSi 2 /Si(111) (M = Ni, Co) systems serve as ideal lattice matched epitaxial M/S heterojunctions to investigate several interface-induced effects. Such a sharp and abrupt lattice matched interface provides an ideal rectifying junction for realization of MIGS and formation of SBH. Depending on the orientation of MSi 2 overlayer with respect to the Si(111) substrate, two types of interfaces can be formed, viz. A-type and B-type. In the present work, we have used first principles density functional theory (DFT) based computational approach, to investigate structure-property relationships at the MSi 2 /Si(111) interface. Interestingly, the estimated p-type SBH are different for the apparently identical looking A- and B-type interfaces. Moreover, our findings on the evolution of MIGS and the estimates of work function are reported here. These results should have a strong bearing on silicon-based device applications. • The transition metal disilicides (MSi 2 ) are important, overall device performance depends on the geometry and electronic structure of the interface. • MSi 2 /Si(111) (M = Ni, Co) systems serve as ideal heterojunctions to investigate interface-induced effects such as metal-induced gap states, formation of Schottky barrier . • Depending on the orientation of MSi 2 overlayer, two types of interfaces can be formed, namely A-type and B-type. • Using first principles DFT approach, the interface properties of the 2D MSi 2 /Si(111) quantum heterostructures have been investigated. • Significant and recent attempts for the applications of this metal/semiconductor heterojunction is in the reconfigurable FET device.