First principles total energy calculations of the surface atomic structure of yttrium disilicide on Si(111)

Rare-earth silicide thin films on the Si(111) surface

“…4 for Tb, Dy, and Er, respectively. This is of the same order of magnitude as in previous calculations for the YSi 2 silicide monolayer [24,29,54]. Interestingly, the orientation of the uppermost bilayer can be switched by H adsorption [57].…”

“…The deposition of a complete silicide monolayer on the Si(111) surface results in regular films with RESi 2 stoichiometry and 1 × 1 periodicity [1]. The model proposed by Stauffer et al for the ErSi 2 monolayer describes the microscopic structure of most rare earth silicide monolayers at the Si(111) surface [21], including DySi 2 [23], HoSi 2 [22], GdSi 2 [24], and YSi 2 [24,29,54]. X-ray diffraction experiments confirmed the suggestion by Stauffer et al for ErSi 2 [55].…”

“…They form irregular edges without any particular orientation [10] and are often characterized by pinholes, stacking faults, and screw dislocations. While epitaxial silicide trilayers [29] and pentalayers [25] with √ 3 × √ 3 periodicity have been theoretically modeled in the past, we focus in this work on a coverage of two monolayers.…”

“…However, no first-principles calculations at the atomic scale that can confirm or reject the proposed models have been performed for most structures up to date. In general, our theoretical knowledge of the two-dimensional rare-earth silicides is largely incomplete and limited to the simplest Y and Er silicide structures [21,[24][25][26][27][28][29]. To the best of our knowledge, no theoretical investigations of the silicide structures in the submonolayer range are available in the literature.…”

Surface electronic structure of two- and three-dimensional holmium silicide on Si(111)

“…Rogero et al 8 used the SIESTA code to geometry optimize the 2D Si͑111͒-1 ϫ 1-Y structure and found a good level of agreement with the structural parameters obtained by LEED. Cocoletzi et al 20 slightly improved these structural parameters and performed the first DFT simulations of a 3D silicide surface, including a detailed investigation of the energetics of the networks of Si vacancies in the graphitic Si layers. The first DFT calculation was that of Magaud et al 21 To help understand the role of the vacancy network in the 3D silicides they looked at the bulk-hexagonal silicide structure formed by the group III RE metal Y, with the choice of RE metal atom being due to the lack of f electrons in Y and the computational savings to be made therein.…”