One-dimensional diffusion of Sr atoms on Sr/Si(111)-3 × 2 reconstruction surface

Structure Stability and Electronic Property for Alkaline-Earth Metals Induced Si(111)-3x2 Surfaces

“…Compared to As, Sb and Bi adatoms on Si(100) surface, our case of AEM adatoms on Si(111)-3×2 surface is obviously a easier diffusion process. In addi- 1 tion, a recent study using STM and scanning tunneling spectroscopy observed a concerted motion of Sr adatom along the empty channel on Si(111)-3×2 surface at room temperature, supporting our calculations [39].…”

“…Analysis of electronic band structures and band-decomposed charge density distributions indicates that the first conduction and the third valence are derived from the top Si and metal atoms, while the first and second valence bands are derived from the bulk Si atoms. As a result, a larger surface band gap of 1.65−1.68 eV is obtained, in good consistent with the experimental observation for Sr/Si(111)-3×2 surface [39].…”

“…The results show that the valence band maximum (VBM) is at Γ and the conduction band minimum (CBM) is along the C-Γ direction, which indicate that Sr/Si(111)-3×2 surface is an indirect band-gap semiconductor with a band gap of 1.44 eV. Like Sr, Ca and Ba adatoms induced Si(111)-3×2 surfaces also present the semiconductive character with a 1.41 and 1.42 eV band gaps, respectively, and the difference is the CBM for Ca/Si(111)-3×2 surface is at C. However, recently a band gap of 1.7 eV for Sr/Si(111)-3×2 surface, reported by Du et al [39], was observed using scanning tunneling microscopy and scanning tunneling spectroscopy, which is larger than the band gap shown above. This phenomenon is, moreover, supported by the previous experimental findings [16,34,36,37,[57][58][59][60][61][62][63].…”

“…We calculate the electronic band structures based on hybrid density functional method (HSE06) [56]. Due to the AEM/Si(111)-3×2 surfaces have the same geometric structure [34,35,39,57], herein, we only show the band structure for Sr/Si(111)-3×2 surface in Fig. 4, and the band structures for Ca and Ba have been provided in the supplementary materials.…”

“…half of the AM coverage). Further experimental observations also indicate their proposals [32] are universal for other AEM atoms (Ca [34][35][36][37] and Sr [38,39]) In addition, the 3×2 spots is hardly observed in LEED pattern for AEM/Si(111)-3×2 surfaces, is primarily derive from the lack of long-range order at room temperature [33,40,41].…”