First principle investigation of the electronic properties of silicon-silicides interfaces

We review the theoretical studies on the reactive interfaces between silicon and transition metals. Much information on the interface compounds can be obtained through an analysis of the electron states of bulk compounds of different structure and stoichiometry. A more detailed analysis of the interface reaction and typical surface information, like the interface geometry or the Schottky barrier height B, can be obtained only through direct investigations of the interface structure. The difficulty of interface calculations can be overcome by using the linear methods devised by Andersen, like the linear augmented plane wave (LAPW) and the linear muffin tin orbitals (LMTO) methods. The LMTO method has been adapted to perform a self-consistent calculation of the electronic properties of the Si(111)-NiSi2 (111) epitaxial interface. This interface has been investigated for both the experimentally observed type-A and type-B orientations. The densities of states projected on the various sites provide, for the first time, a detailed analysis of the interface electronic states. The perturbation due to the interface is shown to be very strong and various interface features are found on the silicon and silicide layers. The computed B is different for the two orientations, with a value of 1.1 eV for the type-A orientation, and 0.8 eV for the staking-fault type-B interface.