Sm-induced reconstructions on Si(111) surface

Surface Science 569 (2004) 23–32

www.elsevier.com/locate/susc

Sm-induced reconstructions on Si(111) surface

E. Ehret *, F. Palmino, L. Mansour, E. Duverger, J.-C. Labrune

FEMTO-ST UMR CNRS 6174, Surface Interface Nanostructure Group, 4 place Tharradin, BP 71427, 25211 Montbeliard cedex, France

Received 19 January 2004; accepted for publication 6 July 2004

Available online 21 August 2004

Abstract

Using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED), the surface recon-

structions induced by submonolayer Sm adsorption on a Si(111) have been studied. This system forms a series of

metal-induced n · 1 (n = 3,5,7,. . .) reconstructions with increase of Sm coverage on the Si(111) substrate at elevated

temperatures. Our STM results indicate that these reconstructions appear as well-ordered row-like structures. Local

mixing of the 3 · 1 and n · 1 unit cells (or stripes) indicates that the atomic models for these phases should be closely

related. The atomically resolved STM images reveal a strong bias dependence which determine the relative registry of

the Si as well as Sm atoms for these reconstructions. Our results are consistent with the chain-channel models of the

row-like structures of the Ca/Si(111) system as proposed in the literature.

� 2004 Elseiver B.V. All rights reserved.

Keywords: Silicon; Scanning tunneling microscopy; Surface relaxation and reconstruction

1. Introduction

Adsorbate-induced chain structures on semi-

conductor surfaces have been the subject of

extensive studies for decades as a model system

for the creation of one-dimensional (1D) systemwith a high degree of perfection [1,2]. The most

well-known examples of such a chain structure

are both the 3 · 1 and 3 · 2 reconstructions in-

duced by the adsorption of a variety of metal

0039-6028/$ - see front matter � 2004 Elseiver B.V. All rights reserv

doi:10.1016/j.susc.2004.07.005

* Corresponding author. Tel.: +33 381 994 688; fax: +33 381

994 610.

E-mail address: [email protected] (E. Ehret).

atoms on the Si(111) substrate. The 3 · 1 recon-

struction is formed by the adsorption of an alka-

li metal (AM) at 1/3 monolayer (ML) coverage

[3–6], whereas the 3 · 2 reconstruction is formed

by the adsorption an alkaline earth metal (AEM)

or a rare-earth metal (REM) at 1/6 ML coverage[7–10]. However, the similarities between the

scanning tunneling microscopy (STM) images

[9–11], the low energy electron diffraction

(LEED) I–V curves [12,13] and the Si2p core le-

vel spectroscopy (CLS) spectra [8,14,15] obtained

from those different reconstructions suggested

that they adopt a common arrangement of Si

adatoms.

ed.

mailto:[email protected]

24 E. Ehret et al. / Surface Science 569 (2004) 23–32

Earlier models have been proposed for the me-

tal-induced 3 · 1 reconstruction, most notable is

the seiwatz-chain and the extended-Pandey-chain

models. Both of these were discarded recently.

The honeycomb-chain channel model (HCC),which incorporates Si double bond in the surface

layer, is now considered to be the most plausible

candidate. The HCC model has the lowest energy

among the one of models proposed so far, and

can best accounts for the experimental results [16].

Others chain structures appear at higher

absorbate coverages. Baski et al. [17] have shown

that the Ca/Si(111) system forms a series of odd-order n · 1 reconstructions that culminate in a

2 · 1 phase at 0.5 ML. This coverage behaviour

is similar to that observed for the divalent rare-

earth Yb and Eu [18–21]. It is suggested that these

additional reconstructions could be formed by an

appropriate combination of Seiwatz and HCC

chains.

The Sm/Si system has not been extensively stud-ied. Previous study reported that the valence state

of the Sm atom changes from divalent to trivalent

with increase of the Sm coverage [22]. LEED

observations and CLS measurements have shown

the presence of n · 1 phases whereas ap3 ·p

3�R30� phase is found at higher coverage. The

Sm atoms are respectively divalent and trivalent

state in these phases [18,23]. In this paper, we haveused STM in conjunction with LEED to investi-

gate the surface structures of Sm on Si(111).

LEED observations reveal that a series of metal-

induced n · 1 (n = 3,5,7,. . .) reconstructions are

formed with increasing Sm coverage on the

Si(111) substrate at elevated temperature. To our

knowledge, for the first time, the detailed STM

observations carefully determine the registry ofthe filled- and empty-state features of these recon-

structions. The appearance and the bias depend-

ence of the STM images are discussed in terms of

previously proposed structural models for the

Ca/Si(111) system.

2. Experiment

The experiments are performed in a two-cham-

ber ultrahigh vacuum system (under a pressure be-

low 3 · 10�10 mbar) equipped with an Omicron

STM and a LEED/AES facilities. The Si(111) sub-

strate (1–3 Xcm resistivity) is carefully degassed

and cleaned in situ by a series of rapid heating

up to 1200 �C under a pressure lower than5 · 10�10 mbar, and subsequently slowly cooled

down in order to obtain the 7 · 7 reconstruction.

Sm deposition is performed using an e-beam evap-

orator onto the Si(111) substrates at about 1/3

ML/min. One ML is referred to the Si(111) ideal

surface atomic density (7.8 · 10�14 atomcm�2).

Sm is deposited onto the substrate held at temper-

ature in the 400–850 �C range. Samples are subse-quently annealed at the temperature deposition

during 20 min. The Sm surface coverage is deter-

mined from STM images for low coverage and

extrapolated to high coverages. The procedure

used for the accurate determination of Sm cover-

age has been described elsewhere [10]. Both LEED

and STM observations are made at room temper-

ature, and the STM images are acquired in theconstant current mode with bias voltage applied

to the sample.

3. Results

3.1. Phase diagram

We have studied surface order as a function of

the Sm coverage and the annealing conditions

using STM as well as LEED. Structural transfor-

mations on the Si(111) surface induced by Sm

adsorption observed in the present study are sum-

marized in Fig. 1.

This formation phase diagram is based on the

STM and LEED observations after Sm depositiononto the clean Si(111)-7 · 7 surface held at vari-

ous constant temperatures. All the samples are

subsequently annealed at the temperature deposi-

tion during 20 min. Note that the lines delimiting

the domain are sloped roughly to adjust the indi-

cated coverage to account for desorption of Sm

at higher temperatures.

From this diagram, we see the following generalfeatures : for coverage less than 1/6 ML and for

substrate temperatures below 450 �C, a diffuse

7 · 7 LEED structure is observed. The 3 · 2 struc-

Fig. 1. Surface phase diagram of the Sm/Si(111) system in the

submonolayer range (up to 2/3 ML). In Gray scale are the

regions where monophases are formed.

E. Ehret et al. / Surface Science 569 (2004) 23–32 25

ture appears at higher temperature (T P 450 �C)

and covers completely the surface at 1/6 ML for

a substrate temperature of 450 �C. The STM

observations reveal a structure with a 3 · 2 perio-

dicity whereas the LEED pattern exhibits a 3 · 1

multidomain structure as shown in Fig. 2a. This

apparent discrepancy between LEED and STMobservations will be discussed in the following.

Fig. 2. LEED patterns for the n · 1 phases of the Sm/Si(111) system

surfaces, observed at RT.

For Sm coverage range of about 0.16–0.34 ML

and for temperature between 450 and 650 �C, a

5 · 1 phase is observed by LEED and STM, ini-

tially coexisting with the 3 · 2 phase. This phase

is complete at 0.34 ML at substrate temperatureof 450 �C. The corresponding 5 · 1 LEED pattern

is presented in Fig. 2b.

Upon further deposition Sm, the 5 · 1 structure

gradually disappears and is replaced by the 7 · 1

phase, which covers completely the surface at

0.38 ML at substrate temperature of 450 �C. The

7 · 1 LEED pattern is shown in Fig. 2c.

Annealing the Sm/Si system to 500 �C reducesthe Sm coverage of 0.05 ML. At temperature

above 750 �C, all the Sm atoms desorb completely

to result in a clean Si(111)-7 · 7 LEED pattern.

The detailed behaviour of each phase will be dis-

cussed in the following. Other reconstructions exist

when increasing coverage due to the interdiffusion

of Sm into the bulk [22]. When the Sm coverage

exceeds 2/3 ML at 450 �C, the entire surface is cov-ered by a

p3 ·

p3�R30� phase. These phases will

not be studied in this paper.

(a) 3 · 1-Sm (86 eV), (b) 5 · 1-Sm (78 eV), (c) 7 · 1-Sm (153 eV)


Note that Sm/Si(111) system does not form

2 · 1 structure whatever the Sm coverage and the

substrate temperature. This behaviour distin-

guishes Sm from pure divalent metals-like Ca

and Yb, where such a reconstruction is observed[17,18,24].

3.2. The 3 · 2 phase

STM data showing the morphology and the

atomic structure of the lowest coverage 3 · 2 phase

is shown in Figs. 3 and 4.

In large-scale empty-state STM image of theFig. 3, the 3 · 2 phase appears as stripes domains

oriented in one of three symmetry directions. The

higher resolution empty-state image of Fig. 4a

shows rows of protrusions running in the ½1�10�direction. The separation between the rows is 3a,

where a ¼ ðffiffiffi

3p

=2Þa0 ¼ 3:32 A [a0 = 3.84 A, a unit

lattice spacing on a bulk terminated Si(111)].

Within the rows, the spacing between the protru-sions is 2a0. We have proposed in a previous paper

[10] that the 3 · 2 protrusions in the empty-state

image are assigned to the Sm atoms occupying a

specific site. The observation of a single protrusion

per 3 · 2 cell in the empty-state STM image with a

Fig. 3. Large scale STM image (40 · 40 nm2) (Vs = 1.8 V and

It = 0.34 nA) showing three domains of the Sm-induced 3 · 2

phases. Scale bar is 5 nm.

Fig. 4. High resolution (a) empty-state (Vs = 1.8 V and

It = 0.34 nA) and (b) filled-state (Vs = �3.2 V and It = 6.11

nA) STM images (5 · 5 nm2) of the 3 · 2 reconstruction. The

zigzag chains of the empty-state image form a 3 · 2 structure

rather than a 3 · 1 structure.

Sm coverage of 1/6 ML is supportive of thisinterpretation.

The filled-state STM image of the Sm/Si(111)-

3 · 2 surface is obtained with atomic resolution

as shown in Fig. 4b. There are bright double rows

running in the ½1�10� direction separated by dark

channels. The protrusions, in the double rows,

form zigzag chains with the ·1 periodicity. Thus,

the apparent unit cell formed by those protrusionsis a 3 · 1. The zigzag chain feature in the filled-



nA) STM images (11 · 11 nm2) of the 5 · 1 reconstruction. For

convenience, the position of the maxima are shown as filled

circles in the empty-state image. Lines with 3a, 2a and 5a

periodicities have been superimposed over the images.


state image is nearly identical to those reported for

the Si(111)3 · 2-Ba phase [9] as well as for the

Si(111)3 · 1-AM [7,17] surfaces. This zigzag chain

feature is attributable to Si atoms, because the

3 · 2 protrusions in the empty-state STM imagesare naturally assigned to adsorbate atoms based

on the coverage of 1/6 ML [10].


As indicated in a previous section, the 5 · 1

phase can be grown in a very narrow range of

temperature and coverage. With a 0.34 ML Smcoverage, the whole surface exhibits a 5 · 1 recon-

struction which is confirmed by the LEED pattern

and STM observations. As shown in the empty-

state STM image of the Fig. 5a, the 5 · 1 phase

consists of double bright rows of protrusions ori-

ented along the ½1�10� direction and with a 5a in-

ter-row spacing. Within the rows, the spacing of

the protrusions is a0. Inside a 5 · 1 unit cell, thebright lines are separated by 2a and the distance

between the bright lines adjacent to a dark

trenches is 3a. A ladder configuration between

the double rows prevails, as shown by the filled cir-

cles in the Fig. 5a.

The chain feature appears differently in the

filled-state images, as shown in Fig. 5b. In the

filled-state, the 5 · 1 reconstruction seems to beconstructed by the combination of a thin bright

row and a bright double row having both

inequivalent contrast. At this point, it is impossi-

ble to distinguish the atomic configuration (i.e.

ladder or zigzag arrangements) of the bright dou-

ble rows.

The Fig. 6 also illustrates the bias-dependent

behaviour of the 5 · 1 phase. To determine therelative positions of the bright features, the bias

voltage is reversed during the scan. The corre-

spondence between the maxima positions in

both empty- and filled-states are indicated by

the dotted and solid outlines in the image. We

see that the position of the bright double rows

in the filled-states (Vs < 0: upper and lower part

of Fig. 6) correspond to the position of thedark trenches of the empty-states (Vs > 0: mid-

dle part of the Fig. 6). The position of the thin

bright row in the filled-states is located at the

trough between the double rows of the empty-

states. The shift of the 5 · 1-Sm chains seems

to indicate that filled- and empty-states are lo-

cated on adjacent atomic rows. Such a lateral

separation of charge could reflect an ionic char-

acter. This feature is similar to the Si(111)3 · 2-

Sm chain structures where the Si and Sm

adatoms are imaged in the filled- and empty-states respectively.

Fig. 6. STM image (12 · 15 nm2) showing the bias polarity

dependence of the 5 · 1 phase. The bias is reversed two times

during the scan (Vs = �1.8 V!1.8 V!�1.8 V and It = 0.04

nA). The positions of the rows are indicated by solid and

dashed lines superimposed over the empty-state (middle part)

and filled-state (lower and upper part) images.



nA) STM images (8 · 8 nm2) of the 7 · 1 reconstruction. For

convenience, the position of the maxima are shown as filled

circles in the empty-state image. Lines with 3a, 2a and 7a

periodicity have been superimposed over the images. Note that

stripes with the 5 · 1 periodicity are present in the filled-state

image.



STM observations show that the whole surface

exhibits a 7 · 1 reconstruction after deposition of

0.45 ML Sm at 500 �C. Closer inspection of theseSTM images (Fig. 7a) at positive sample bias

shown that the 7 · 1 reconstruction consists of

stripes of 7a wide composed of three rows with

the same width of 2a. Like the empty-state image

of the 5 · 1 reconstruction (see Fig. 5a), a ladder

configuration between the triple rows prevails.

Within the rows, the spacing of the protrusions

is a0. The filled-state image of the Sm/Si(111)seems to be more complex. However, the main

feature of these images is the presence of two zig-

zag chains surrounded by a clearly visible bright

row. The spacing between the protrusions within

the rows is a0 as indicated by white circles in the

Fig. 7b.

When reversing the bias in Fig. 8, the zigzag

chains and the row in the filled-state image (bot-tom of Fig. 8) shift significantly. The position of

the bright features row in the filled-state image

corresponds to the position of the dark trenches

of the empty-state images (upper part of Fig. 8).

Similar to the 5 · 1 phase, the shift of the 7 · 1-

Sm chains indicates that filled- and empty-states

are located on adjacent atomic rows.

4. Discussion

The honeycomb-chain channel model (HCC)

which incorporates Si double bond in the surface

layer has been proposed for the metal-induced

3 · 1 reconstruction. The substrate reconstruction

structure of this model is a 3 · 1 reconstruction

Fig. 8. STM image (10 · 10 nm2) showing the bias polarity

dependence of the 7 · 1 phase. The bias is reversed during the

scan (Vs = �1.8 V!2.1 V and It = 0.25 nA). The positions of

the rows are indicated by solid and dashed lines superimposed

over the empty-state (upper part) and filled-state (lower part)

images.


constituted by four inequivalent Si adatoms which

form a ‘‘honeycomb chain’’ parallel to the surface

plane (the top Si layer reconstruction structure).These four Si atoms are threefold coordinated

and the inner atoms are in a planar configuration.

With the adsorption of the metal atom in the chan-

nel between the ‘‘honeycomb chain’’, the surface

structure acquires a 3 · 1 or 3 · 2 periodicity

dependent on the valency of the adsorbate. The

(HCC) model for the 3 · 2 reconstruction is repre-

sented in Fig. 11a.In a recent paper [10], we have interpreted the

Si(111)3 · 2-Sm reconstruction in terms of the

HCC model from the combined study of STM,

LEED and ab initio calculations. The 1/6 ML

Sm coverage was accommoded by putting one

Sm atom in every second 3 · 1 unit cell of the

HCC structure. The HCC structure is stabilized

by the saturation of the dangling bonds of the Siatoms surrounding the positively-ionized Sm. This

results in bright protrusions with the zigzag chain

appearance in the filled-state STM images shown

in Fig. 4b whereas in the empty-state STM image

of the Fig. 4a, the Sm atoms appear as rows of

bright protrusions with · 2 periodicity.

Let us return to LEED data. While the LEED

(Fig. 2a) exhibits a 3 · 1 pattern, the STM shows

the 3 · 2 surface structure (Fig. 3). We suggested

that the apparent discrepancy of the LEED and

STM data is explained by the lack of sensitivityof the Sm atoms with poor long-range order. Thus,

the 3 · 1 LEED pattern only reflects the well-or-

dered reconstruction structure of the (HCC) top

Si layer like the filled-state STM images does.

It is interesting to compare our experimental re-

sults of the 5 · 1-Sm and 7 · 1-Sm structures with

the other systems such as Ca and Yb [17,18,24].

These metals form high order n · 1 phases follow-ing the sequence (3 · 1), (5 · 1), (7 · 1) and (2 · 1)

for increasing the coverage. The present study

shows the (3 · 2), (5 · 1) and (7 · 1) sequence. As

a rule, one should not expect these reconstructions

to be identical because the 2 · 1 phase for the Sm/

Si(111) system is missing of the sequence. How-

ever, the previous works [17,24] of the Ca/

Si(111) system show interesting similarities. The5 · 1-Sm and 7 · 1-Sm structures in the empty-

state images appear as double and triple rows of

protrusions with ·2a periodicity separated by

·3a wide dark gaps. It is therefore suggested that

these high order n · 1 phases can be considered

as a mixture of 3 · 1 and 2 · 1 subunit cells. Fur-

ther evidence for this assumption is the local for-

mation of others n · 1 phases at Sm coverageswhere the 5 · 1 phase coexists with the 3 · 2 phase.

Indeed, at a appropriate Sm coverage, large

patches of the 8 · 2 reconstruction, which incorpo-

rate two 3 · 1 unit cells and one 2 · 1 unit cell,

appear on the Si(111) surface as shown in the

empty-state STM image of Fig. 9. These STM re-

sults fully support the view that the 3 · 1 and n · 1

phases should have closely related atomic models.On the basis of dual-polarity STM images and

ab initio calculations, it has been suggested that

the odd-order n · 1 (n = 3,5,7,. . .) phases of the

Ca/Si(111) interface consist of HCC chains (3 · 1

structural unit) and Seiwatz chains (2 · 1 struc-

tural unit) where the Ca atoms sit in the channel

between the Si chains. Notice that the Seiwatz

chain is a unit of the Seiwatz model previouslyproposed by Weitering et al. for the 3 · 1 AM

structures [8]. This is a missing top layer recon-

struction incorporating fivefold Si rings. We

Fig. 9. High resolution empty-state STM image (20 · 20 nm2)

showing a local mixing of the 3 · 1 and n · 1 phases (Vs = 1.7 V

and It = 0.20 nA). At a appropriate Sm coverage, large patch of

the 8 · 2 reconstruction are formed on the surface. Fragments

of higher order 11 · 2 reconstructions are also visible.

Fig. 10. Structural models for the Si(111) n · 1-Sm surfaces.

(a) The HCC model for the 3 · 2-Sm surface, (b) the

HCC + Seiwatz models for the 5 · 1-Sm and (c) the 7 · 1-Sm

surfaces. Solid lines indicate a unit cell of the corresponding

structures.


presented in the Fig. 10, the possible structure

models for the Sm/Si(111) 5 · 1 and 7 · 1 basedon a combination of HCC and Seiwatz models

as reported for the Ca/Si(111) system.

Let us consider the consistency of these models

to the results of the present STM observations. In

order to determine the exact location of the bright

features in the n · 1 STM images, a top view of the

structural models have been superimposed onto

the atomically resolved STM images. The resultis shown in Figs. 11 and 12. This superimposition

take into account the shift between the bright fea-

tures of the filled-state and empty-state STM

images as seen above in Figs. 6 and 8.

In the empty-states of the 5 · 1-Sm and 7 · 1-

Sm structures (Figs. 11a and 12a), the individual

Sm chains of the superimposed models are all lo-

cated over the double and triple rows of brightprotrusions of the STM images. The Si adatoms

of the HCC and Seiwatz chains appear as dark fea-

tures. We see clearly that the position of the wider

dark trenches between the double and triple rows

is associated with the Si adatoms of the HCC

chains. In the filled-states images (Figs. 11b and

12b), the Sm is here located at the trough between

the bright rows which correspond to Si adatoms.

However, all the Si adatoms are not associated

with a maxima in these filled-state STM images.The Fig. 12b shows that the inner Si of the HCC

chains are located at the dark trenches between

the bright features in the empty-states of the

7 · 1-Sm phase as observed for the 3 · 2-Sm phase.

We note that the detailed contrast is quite different

in the the empty-states for the 5 · 1-Sm phase (Fig.

11b), emphasising a more complicated bias

dependence of the STM images.The proposed structural models of the

Si(111)n · 1-Sm phases can also be tested by

determining the absolute coverage of the absorb-

ate. In our growth studies, we are be able to assign

a specific Sm coverage to the n · 1 phases since it is

Fig. 11. Magnified (a) empty-state (Vs = 1.8 V and It = 1.02

nA) and (b) filled-state (Vs = �3.7 V and It = 0.08 nA) STM

images of the 5 · 1-Sm reconstruction (6 · 6 nm2). Schematic

diagram of the corresponding structural models are superim-

posed over the images.

Fig. 12. Magnified (a) empty-state (Vs = 1.7 V and It = 0.45

nA) and (b) filled-state (Vs = �2.8 V and It = 0.43 nA) STM

images of the 7 · 1-Sm reconstruction (4 · 4 nm2). Schematic

diagram of the corresponding structural models are superim-

posed over the images.


formed at substrate temperature at which Sm

desorption is very low. From our STM observa-

tions, we estimate that the Sm coverages for the

5 · 1 and 7 · 1 phases are 0.34 and 0.38 ML

respectively. This is also consistent with the 5 · 1

and 7 · 1 models which require a Sm density of

0.4 and 0.43 ML respectively.

Taking into account the information providedby the coverage determination, the polarity

dependence and the registration of the STM

images, we propose that Si(111) n · 1-Sm (n = 5,

7,. . .) surfaces consist of Seiwatz and HCC-based

Si substrate reconstruction structures. It should

be noted that the electronic nature of the n · 1-

Sm (n = 5,7, . . .) surfaces depends on the Sm cov-

erage. The 5 · 1-Sm and 7 · -Sm surfaces with a

Sm density of 0.4 and 0.43 ML respectively shouldbe metallic due to electron counting consideration.

However, the STM images have been recorded


with sample biases of about 2 V suggesting that

these surfaces are semiconducting like. The reason

for this is not clear at this stage. Further experi-

ments, particularly photoemission measurements

are required to clarify the exact electronic natureof these surfaces.

5. Conclusion

We have been studied the surface reconstruc-

tions induced by submonolayer Sm adsorption

on a Si(111). This system forms a series ofmetal-induced n · 1 (n = 3,5,7,. . .) reconstructionswith increase of Sm coverage on the Si(111) sub-

strate at elevated temperatures. Our STM results

indicate that these reconstructions appear as

well-ordered row-like structures. Local mixing of

the 3 · 1 and n · 1 unit cells (or stripes) indicates

that the atomic models for these phases should

be closely related. The atomically resolved STMimages reveal a strong bias dependence which

determine the relative registry of the Si as well as

Sm atoms for these reconstructions. We presented

in the Fig. 10, the possible structure models for the

Sm/Si(111) 5 · 1 and 7 · 1 based on a combina-

tion of HCC and Seiwatz models as reported for

the Ca/Si(111) system.

References

[1] J. Nogami, Surf. Rev. Lett. 7 (2000) 555.

[2] A. Kirakosian, J.L. McChesney, R. Bennwitz, J.N. Crain,

J.-L. Lin, F.J. Himpsel, Surf. Sci. 498 (1999) 109.

[3] K. Sakamoto, T. Okuda, H. Nishimoto, H. Daimon, S.

Suga, T. Kinoshita, A. Kakisaki, Phys. Rev. B 50 (1994)

1725.

[4] T. Okuda, H. Daimon, S. Suga, Y. Tezuka, S. Ino, Surf.

Sci. 122/123 (1997) 89.

[5] A.A. Saranin et al., Phys. Rev. B 58 (1998) 7059.

[6] H.H. Weitering, X. Shi, S.C. Erwin, Phys. Rev. B 54

(1996) 10585.

[7] A.A. Saranin, A.V. Zotov, V.G. Lifshits, M. Katayama,

K. Oura, Surf. Sci. 426 (1999) 298.

[8] H.H. Weitering, Surf. Sci. Lett. 355 (1996) 271.

[9] G. Lee, S. Hong, H. Kim, D. Shin, J. Koo, H. Lee, D.W.

Moon, Phys. Rev. Lett. 87 (2001) 56104.

[10] F. Palmino, E. Ehret, L. Mansour, J.-C. Labrune, G. Lee,

H. Kim, J.-M Themlin, Phys. Rev. B 67 (2003) 195413.

[11] D. Jeon, T. Hashizume, T. Sakurai, J. Vac. Sci. Technol. B

12 (1994) 2044.

[12] W.C. Fan, A. Ignatiev, Phys. Rev. B 41 (1990) 3592.

[13] J. Quinn, F. Jona, Surf. Sci. 249 (1991) L307.

[14] C. Wigren, J.N. Andersen, R. Nyholm, M. Gothelid, M.

Hammar, C. Tornevik, U.O. Karlson, Phys. Rev. B 48

(1993) 11014.

[15] K. Sakamoto, W. Takeyama, H.M. Zhang, R.I.G. Uhr-

berg, Phys. Rev. B 66 (2002) 165319.

[16] S. Erwin, H.H. Weitering, Phys. Rev. Lett. 81 (1998) 2296.

[17] A.A. Baski, S.C. Erwin, M.S. Turner, K.M. Jones, J.W.

Dickinson, J.A. Carlisle, Surf. Sci. 476 (2001) 22.

[18] C. Wigren, J.N. Andersen, R. Nyholm, U.O. Karlson, J.

Nogami, A.A. Baski, C.F. Quate, Phys. Rev. B 47 (1993)

9663.

[19] R.-L. Vaara, M.V. Kuzmin, R.E. Perala, P. Laukkanen,

I.J. Vayrynen, Surf. Sci. 529 (2003) L229.

[20] M.V. Kuzmin, R.-L. Vaara, P. Laukkanen, R.E. Perala,

I.J. Vayrynen, Surf. Sci. 538 (2003) 124.

[21] M.V. Kuzmin, R.-L. Vaara, P. Laukkanen, R.E. Perala,

I.J. Vayrynen, Surf. Sci. 549 (2004) 183.

[22] A. Franciosi, J.H. Weaver, P. Perfetti, A.D. Katnani, G.

Margaritondo, Solid. State Commun. 47 (1983) 427.

[23] T.V. Krachino, M.V. Kuzmin, M.V. Loginov, M.A.

Mittsev, Phys. Solid State 40 (1998) 341.

[24] T. Sekiguchi, F. Shimokoshi, T. Nagao, S. Hasegawa,

Surf. Sci. 493 (2001) 148.

Sm-induced reconstructions on Si(111) surface

Documents

Transcript of Sm-induced reconstructions on Si(111) surface