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Delocalized Surface State in Epitaxial Si(111) Film with Spontaneous √3 × √3 Superstructure.

Chen J, Du Y, Li Z, Li W, Feng B, Qiu J, Cheng P, Xue Dou S, Chen L, Wu K - Sci Rep (2015)

Bottom Line: The "multilayer silicene" films were grown on Ag(111), with increasing thickness above 30 monolayers (ML).On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns.Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
The "multilayer silicene" films were grown on Ag(111), with increasing thickness above 30 monolayers (ML). Scanning tunneling microscopy (STM) observations suggest that the "multilayer silicene" is indeed a bulk-like Si(111) film with a (√3 × √3)R30° honeycomb superstructure on surface. The possibility for formation of Si(111)(√3 × √3)R30°-Ag reconstruction on the surface can be distinctively ruled out by peeling off the surface layer with the STM tip. On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns. Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si.

No MeSH data available.


Related in: MedlinePlus

The STM observation of Si film with different layers on Ag(111) surface.(a) STM image (Vtip = 0.9 V, I = 100pA, 20 × 20 nm2) of the first two √3 layers on Ag(111). (b) The heights of the first two √3 layers as a function of tip bias. (c,d) STM images (Vtip = −1.0 V, I = 100pA, 200 × 200 nm2) of multilayer Si films with different thickness. The inset is high resolution STM image (Vtip = −0.5 V, I = 100 pA, 6 × 6 nm2) on the top surface of the film in (d), being √3 × √3 reconstructed. (e) The line profiles across the substrate to the Si films along the dash lines in (c) and (d), respectively. The measured film thicknesses are indicated. (f) dI/dV curves obtained on surface of Si films with different thickness. The curves are vertically shifted for clarity.
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f1: The STM observation of Si film with different layers on Ag(111) surface.(a) STM image (Vtip = 0.9 V, I = 100pA, 20 × 20 nm2) of the first two √3 layers on Ag(111). (b) The heights of the first two √3 layers as a function of tip bias. (c,d) STM images (Vtip = −1.0 V, I = 100pA, 200 × 200 nm2) of multilayer Si films with different thickness. The inset is high resolution STM image (Vtip = −0.5 V, I = 100 pA, 6 × 6 nm2) on the top surface of the film in (d), being √3 × √3 reconstructed. (e) The line profiles across the substrate to the Si films along the dash lines in (c) and (d), respectively. The measured film thicknesses are indicated. (f) dI/dV curves obtained on surface of Si films with different thickness. The curves are vertically shifted for clarity.

Mentions: A monolayer silicene film grown on Ag(111) surface exhibits a variety of different structural phases such as 4 × 4322232425, √13 × √1334, √7 × √7325, 2√3 × 2√32425 (with respect to Ag(111) surface lattice) and √3 × √336 (with respect to silicene 1 × 1). On the other hand, “multilayer silicene” films only exhibit √3 × √3 honeycomb superstructure, as shown in Fig. 1(a). The line profile in Fig. 1(b) shows that the apparent height of the first √3 layer varies significantly from 0 to 0.48 nm with bias, whereas the height of second √3 layer, 0.31 nm, is almost constant. This can be explained by the fact that the local density of states (LDOS) is different on the √3 layer surface and the Ag(111). On the other hand, the almost constant height for thicker √3 layers indicates the same LDOS for different √3 layers. We have analyzed the layer distance for different layer thickness, and we obtained strictly 0.31 ± 0.02 nm, which coincides with the layer distance in bulk Si(111) layers.


Delocalized Surface State in Epitaxial Si(111) Film with Spontaneous √3 × √3 Superstructure.

Chen J, Du Y, Li Z, Li W, Feng B, Qiu J, Cheng P, Xue Dou S, Chen L, Wu K - Sci Rep (2015)

The STM observation of Si film with different layers on Ag(111) surface.(a) STM image (Vtip = 0.9 V, I = 100pA, 20 × 20 nm2) of the first two √3 layers on Ag(111). (b) The heights of the first two √3 layers as a function of tip bias. (c,d) STM images (Vtip = −1.0 V, I = 100pA, 200 × 200 nm2) of multilayer Si films with different thickness. The inset is high resolution STM image (Vtip = −0.5 V, I = 100 pA, 6 × 6 nm2) on the top surface of the film in (d), being √3 × √3 reconstructed. (e) The line profiles across the substrate to the Si films along the dash lines in (c) and (d), respectively. The measured film thicknesses are indicated. (f) dI/dV curves obtained on surface of Si films with different thickness. The curves are vertically shifted for clarity.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f1: The STM observation of Si film with different layers on Ag(111) surface.(a) STM image (Vtip = 0.9 V, I = 100pA, 20 × 20 nm2) of the first two √3 layers on Ag(111). (b) The heights of the first two √3 layers as a function of tip bias. (c,d) STM images (Vtip = −1.0 V, I = 100pA, 200 × 200 nm2) of multilayer Si films with different thickness. The inset is high resolution STM image (Vtip = −0.5 V, I = 100 pA, 6 × 6 nm2) on the top surface of the film in (d), being √3 × √3 reconstructed. (e) The line profiles across the substrate to the Si films along the dash lines in (c) and (d), respectively. The measured film thicknesses are indicated. (f) dI/dV curves obtained on surface of Si films with different thickness. The curves are vertically shifted for clarity.
Mentions: A monolayer silicene film grown on Ag(111) surface exhibits a variety of different structural phases such as 4 × 4322232425, √13 × √1334, √7 × √7325, 2√3 × 2√32425 (with respect to Ag(111) surface lattice) and √3 × √336 (with respect to silicene 1 × 1). On the other hand, “multilayer silicene” films only exhibit √3 × √3 honeycomb superstructure, as shown in Fig. 1(a). The line profile in Fig. 1(b) shows that the apparent height of the first √3 layer varies significantly from 0 to 0.48 nm with bias, whereas the height of second √3 layer, 0.31 nm, is almost constant. This can be explained by the fact that the local density of states (LDOS) is different on the √3 layer surface and the Ag(111). On the other hand, the almost constant height for thicker √3 layers indicates the same LDOS for different √3 layers. We have analyzed the layer distance for different layer thickness, and we obtained strictly 0.31 ± 0.02 nm, which coincides with the layer distance in bulk Si(111) layers.

Bottom Line: The "multilayer silicene" films were grown on Ag(111), with increasing thickness above 30 monolayers (ML).On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns.Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
The "multilayer silicene" films were grown on Ag(111), with increasing thickness above 30 monolayers (ML). Scanning tunneling microscopy (STM) observations suggest that the "multilayer silicene" is indeed a bulk-like Si(111) film with a (√3 × √3)R30° honeycomb superstructure on surface. The possibility for formation of Si(111)(√3 × √3)R30°-Ag reconstruction on the surface can be distinctively ruled out by peeling off the surface layer with the STM tip. On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns. Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si.

No MeSH data available.


Related in: MedlinePlus