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

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 (MSi2) are essential parts of the silicon-based devices. MSi2/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 MSi2 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 MSi2/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 (MSi2) are important, overall device performance depends on the geometry and electronic structure of the interface.•MSi2/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 MSi2 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 MSi2/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.