Scanning tunneling microscopy study of silicide structure on Si(110) surface

Surface structures of Ni-deposited Si(110) after annealing at various temperatures have been investigated using scanning tunneling microscopy (STM). After deposition of a few monolayers (ML) of Ni at room temperature, Ni clusters cover the surface homogeneously, where initial stripe patterns of up and down terraces, characteristic of Si(110)-"16 x 2", are still visible. After annealing above 400 degrees C, NiSi2 islands with (1 x 1) periodicity grow on the Si substrate showing various Ni-induced reconstructions. Detailed STM images of the surface of the islands have revealed that paired bright protrusions are randomly distributed on the (1 x 1) terrace. We have proposed a structural model where adjacent Si atoms in the NiSi2(110) surface form dimers in the [001] direction forming a (1 x 1) terrace, on which pairs of dimers are located at geometrically identical sites on the next grown NiSi2 layer.