Synthesis and properties of crystalline thin

film of antimony trioxide on Si (100)

Abstract

Atomic-scale understanding

and processing of the surface

and interface properties of

antimony trioxide (Sb2O3) are

essential to the development

of nanoscale Sb2O3 materials

for various applications such

as photocatalysts, transpar-

ent conducting oxides, optical

coatings, dielectric films, and

fire retardants. Lack of atomi-

cally well-defined, crystalline

Sb2O3 templates has however

hindered atomic resolution

characterization of the Sb2O3

properties. We report the

preparation of crystalline

Sb2O3 thin films on the Si

(100) substrate with a simple

process by oxidizing Sb-

covered Si(100) in proper

conditions. Physical proper-

ties of the synthesized films

have been elucidated by low

energy electron diffraction,

scanning tunneling microsco-

py and spectroscopy, and ab

initio calculations. The spec-

troscopic results show that

the band gap of Sb2O3 is 3.6

eV around the gamma point

(i.e., ). Calculations reveal

energetically favored Sb2O3

(100) surface structures. The

findings open a new path for

the atomic-scale research of

Sb2O3.

Figure 1. (a) Large-scale empty-state

STM image from Sb2O3/Si

(100); tunneling current

0.25 nA and voltage 2.32

V. Inset shows LEED pat-

tern from the same sam-

ple. (b) Zoomed-in STM

image with the contour line along the

white arrow; tunneling current 0.11 nA

and voltage 2.45 V.

Figure 2. Zoomed-in empty-state

(left)/ filled state (right) STM image

from Sb2O3/Si(100); tunneling cur-

rent 0.11 nA and voltage 2.45 V/1.7

V. (Left) The green square is repre-

senting that two white protrusion in

a unit cell in the two

orthogonal directions

are dimmer if we

compare it with the

calculated data. The

red square is showing

the actual unit cell of

deposited film. (b)-(f) Different

surface models for Sb2O3 and

corresponding simulated STM

images below the models.

Figure 3. Differentiated STS curve meas-

ured from a smooth island area of the

Sb2O3 film. The

band gap of the

film is found to be

3.6 eV, as deduced

with projections of

the valence and

conduction band edges on the voltage axis.

RESULTS

Summary

The formation of crystalline

cubic Sb2O3 on the Si(100)

substrate has been demon-

strated. The synthesis meth-

od is simple, and based on

the controlled oxidation of

Sb-covered Si templates. The

substrate temperature and

the oxidation time play a key

role in the properties of de-

posited thin film. The pre-

sented microscopic results

confirm the deposition of a

well-ordered and smooth

two-dimensional film. The

spectroscopic measurements

show the direct band gap of

3.60.1 eV for senarmontite

Sb2O3. Ab initio calculations

reveal most probable (100)

surface structures for the

Sb2O3 film. The findings

open a new path for the re-

search and development of

Sb2O3 materials.

M.Yasir1 M. Kuzmin1,2 M.P.J. Punkkinen1 J. Mkel1 M. Tuominen1 J. Dahl1 P. Laukkanen1 K. Kokko1

1 Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland

2 Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021, Russian Federation

References

M. Yasir, M.Kuzmin, M. P. J. Punkkinen,J. Mkel, M.

Tuominen, J. Dahl, P.Laukkanen and K. Kokko, Applied

Surface Sciences, 2015.