Theoretical investigation of surface states and energetics of PtSi surfaces

Abstract

Platinum silicide (PtSi) is highly promising material for applications in microelectronic devices. In this article, the surface electronic structure, surface energetics and work functions of stoichiometric and non-stoichiometric PtSi(010) surfaces are explored within the framework of first-principle density functional theory. The surface rumpling is found to be significant only for the top surface layer. The computed values of the rumpling parameter for the top three layers are ~11.0%, ~0.9% and ~1.9%. Further, the interlayer relaxation is found to be largest for the top layer and decreases rapidly for inner layers. Localized surface states are obtained in the valence band at ~9.0eV below the Fermi level. Under rich Pt and Si growth conditions, nonstoichiometric (010) terminations are found to have the lowest surface energies, whereas stoichiometric termination has the lowest surface energy (~1.74J/m2) under mixed conditions. The work function of stoichiometric (010) termination is computed to be 5.15eV and differ as much as by ±0.5eV for nonstoichiometric terminations.