thin film

Topics: Chemical vapor deposition, Physical vapor deposition, Vacuum Pages: 12 (2583 words) Published: January 22, 2014
Applied Surface Science 177 (2001) 152±157

Solution growth and characterization of amorphous
selenium thin ®lms
Heat transformation to nanocrystalline gray
selenium thin ®lms
Biljana Pejova*, Ivan Grozdanov
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, PO Box 162, Arhimedova 5, 91000 Skopje, Macedonia
Received 24 August 2000; accepted 31 January 2001

Abstract
A novel solution growth methodology for fabrication of amorphous, red selenium thin ®lms and their conversion to the hexagonal, gray modi®cation is presented. The method is based on deposition process from aqueous solution of selenosulfate by citric or ascorbic acid as oxidizing agents. The X-ray diffraction method is used for identi®cation of the deposited materials. Ultra-thin ®lms of both amorphous and hexagonal selenium are highly transparent in the Vis±NIR spectral region. # 2001 Elsevier Science B.V. All rights reserved.

PACS: 81.15.-z; 81.05.Cy
Keywords: Selenium thin ®lm; Solution growth method; Optical band gap energy

1. Introduction
In recent years, the thin ®lms of inorganic semiconductor materials are of considerable interest in the ®eld of science and technology. Many techniques for
fabrication of thin ®lms of these materials have been
developed, such as solution growth, electrodeposition,
physical vapor deposition, chemical vapor deposition,
spray pyrolysis, etc. The solution growth technique
(also known as chemical bath deposition, electroless
plating or controlled precipitation) is the simplest and
most economical one. It does not require sophisticated
*
Corresponding author.
E-mail address: biljana@iunona.pmf.ukim.edu.mk (B. Pejova).

instrumentation, is convenient for both small- and
large-area deposition, any kind of shape or size of
the substrates can be used and the starting chemicals
are commonly available and cheap materials.
Following the current trends in microelectronics
materials, continuing our work in the ®eld of thin
®lms of semiconducting materials [1±7], we have
developed a novel solution growth technique for
fabrication of selenium thin ®lms. Some methods,
such as photodeposition, RF sputtering, vacuum evaporation, vacuum deposition by electrochemical decomposition [8±11] have been reported for preparation of these thin ®lms, but to the best of our knowledge, the solution growth methodology has not been used so far for the preparation of thin ®lms of

0169-4332/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 9 - 4 3 3 2 ( 0 1 ) 0 0 1 9 1 - X

B. Pejova, I. Grozdanov / Applied Surface Science 177 (2001) 152±157

selenium. However, after submission of this paper, a
letter appeared in which a method of forming layers of
trigonal Se by reduction of SeO2 with hydrazine is
presented [12].
It is known that selenium exists in several allotropic
forms: monoclinic, hexagonal and amorphous [13,14].
The three red monoclinic (a, b and g) phases consist of
puckered Se8 rings. Thermodynamically most stable
form of the element is the hexagonal, i.e. the gray,
``metallic'' selenium, consisting of long helical
chains. There are two amorphous forms of selenium-red and black with complex and irregular structure. The black selenium consists of large polymeric rings having up to 1000 atoms per ring. The red,

amorphous selenium has a deformed chain structure,
high resistivity …r ˆ 1013 À1016 O cm† [15] and
upon heat treatment transforms to stable hexagonal
modi®cation.
In recent years, the great interest in various allotropes of selenium and their interconversion is due to its use in electronics and solid-state technology
[9,10,13,16]. Selenium exhibits both photovoltaic
and photoconductive action. These properties make
selenium useful in the production of photocells and
exposure meters for photographic use, as well as solar
cells. Selenium is also extensively used in recti®ers, in
xerography,...


References: Chem. 9 (1999) 2889.
B. Pejova, I. Grozdanov / Applied Surface Science 177 (2001) 152±157
[2] B
45 (2000) 269.
[3] I. Grozdanov, M. Najdoski, S.K. Dey, Mater. Lett. 38 (1999)
28.
Chem. 8 (1998) 2213.
Surf. Sci. 165 (2000) 271.
Films 359 (2000) 125.
[13] N.N. Greevwood, A. Earnshaw, Chemistry of the Elements,
2nd Edition, Pergamon Press, Oxford, 1997 (Chapter 16).
[14] P.I. Sampath, J. Chem. Phys. 45 (1966) 3519.
[15] J.H. Dessauer, H.E. Clarc (Eds.), Herography and Related
Processes, The Focal Press, London, 1965 (Chapter 3).
[17] M. Froment, D. Lincot, Electrochem. Acta 40 (1995) 1293.
[18] S. Gorer, A. Albu-Yaron, G. Hodes, Chem. Mater. 7 (1995)
1243.
[19] M.T. Weller, Inorganic Materials Chemistry, Oxford Science,
Oxford, 1994, p
[20] R. Dalven, Introduction to Applied Solid State Physics,
Plenum Press, New York, 1990, p
[21] L.V. Azaroff, M.J. Buerger, The Powder Method, McGrawHill, New York, 1958.
London, 1960.
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