Atomic and electronic structures of the ordered23×23and molten1×1phase on the Si(111):Sn surface

Abstract

The Si͑111͒ surface with an average coverage of slightly more than one monolayer of Sn, exhibits a 2 ͱ 3 ϫ 2 ͱ 3 reconstruction below 463 K. In the literature, atomic structure models with 13 or 14 Sn atoms in the unit cell have been proposed based on scanning tunneling microscopy ͑STM͒ results, even though only four Sn atoms could be resolved in the unit cell. This paper deals with two issues regarding this surface. First, high-resolution angle-resolved photoelectron spectroscopy ͑ARPES͒ and STM are used to test theoretically derived results from an atomic structure model comprised of 14 Sn atoms, ten in an underlayer and four in a top layer ͓C. Törnevik, M. Hammar, N. G. Nilsson, and S. A. Flodström, Phys. Rev. B 44, 13144 ͑1991͔͒. Low-temperature ARPES reveals six occupied surface states. The calculated surface band structure only reproduces some of these surface states. However, simulated STM images show that certain properties of the four atoms that are visible in STM are reproduced by the model. The electronic structure of the Sn atoms in the underlayer of the model does not correspond to any features seen in the ARPES results. STM images are presented which indicate the presence of a different underlayer consisting of eight Sn atoms, which is not compatible with the model. These results indicate that a revised model is called for. The second issue is the reversible transition from a 2 ͱ 3 ϫ 2 ͱ 3 phase below 463 K to a 1 ϫ 1 phase corresponding to a molten Sn layer, above that temperature. It is found that the surface band structure just below the transition temperature is quite similar to that at 100 K. The surface band structure undergoes a dramatic change at the transition. A strong surface state, showing a 1 ϫ 1 periodicity, can be detected above the transition temperature. This state resembles parts of two surface states which, already before the transition temperature is reached, have begun a transformation and lost much of their 2 ͱ 3 ϫ 2 ͱ 3 periodicities. Calculated surface band structures obtained from 1 ϫ 1 models with one monolayer of Sn are compared with ARPES and STM results. It is found that the strong surface state present above the transition temperature shows a dispersion similar to that of a calculated surface band originating from the Sn-Si interface with the Sn atoms in T 1 sites.

Ultrafast Atomic Diffusion Inducing a Reversible(23×23)R30°↔(Srour1, Trabada2, Martínez3 et al. 2015Phys. Rev. Lett.7050View full textAdd to dashboardCite

“…The bright protusions shown by each tetramer are mainly associated with the two central Sn atoms of the tetramer that are ∼0.9-1.0 Å higher than the other Sn atoms. This explains the similarity of our images with those obtained for the Sn=Sið111Þ-2 ffiffi ffi 3 p surface, that presents a Sn double layer and a melting transition [39,40]. We can discard a Sn double layer for our system by measuring the step height between Sn=Sið111Þ∶B-2 ffiffi ffi 3 p and …”

Scanning tunneling microscopy study of PTCDI on Sn/Si(111)-23×23

“…The Sn/Si(111)-2 √ 3 × 2 √ 3 reconstruction, henceforth called Sn-2 √ 3, is a metal-induced reconstruction formed at a Sn coverage above 1 monolayer (ML). [15][16][17][18] There is not yet consensus about the atomic structure of the Sn-2 √ 3 reconstruction. Based on scanning probe microscopy and photoemission studies, models with a double layer structure involving 12-14 atoms per unit cell have been suggested.…”

“…The top most layer includes two inequivalent pairs of Sn adatoms. [15][16][17][18][19] The Sn-2 √ 3 surface is an interesting substrate for growing perylene derivatives. First, the size of its unit cell (13.3 × 13.3 Å 2 ) is of comparative size to PTCDA (14.…”

Photoelectron spectroscopy studies of PTCDI on Ag/Si(111)-3×3

“…The Sn/Si(111)-× 2 3 2 3 surface, henceforth Sn-2 3 , is a metalinduced reconstruction formed at a Sn coverage above 1 monolayer (ML) [8][9][10][11]. There is to this date no consensus about the exact atomic configuration of the surface.…”

“…There is to this date no consensus about the exact atomic configuration of the surface. Scanning probe microscopy studies and photoelectron spectroscopy studies suggest that the surface has a double layer of Sn atoms, a top layer consisting of two inequivalent Snpairs and a bottom layer consisting of 8-10 Sn atoms [8][9][10][11][12]. The simpler Sn/Si(111)-surface contains dangling bonds which causes a strong chemical reaction that causes the PTCDA to stand up on the surface, which does not allow for ordered growth at low coverages [13].…”