ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 1, pp. 66!70. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + M.B. Dergacheva, V.N. Statsyuk, L.A. Fogel’, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 1, pp. 67!71.
AND CORROSION PROTECTION OF METALS
Electrochemical Preparation of Semiconducting CdTe Films
from Ammonia!Chloride Solutions Containing 2,2<-Bipyridine
M. B. Dergacheva, V. N. Statsyuk, and L. A. Fogel’
Sokol’skii Institute of Organic Catalysis and Electrochemistry, National Academy of Sciences
of the Republic of Kazakhstan, Almaty, Kazakhstan
Received June 14, 2006
Abstract-An ammonia3chloride electrolyte containing 2,2`-bipyridine for preparing CdTe deposits on
a glassy carbon electrode with a particle size of 335 nm was developed. The joint electroreduction of Cd(II)
and Te(IV) ions was studied by voltammetry.
The existing methods for preparing semiconductor
compounds with a particle size of 2.5325 nm are
labor-consuming and involve large number of opera-
tions. To such methods belong pyrolysis of organic
reagents, dispersion sputtering on heated substrates,
and chemical deposition from colloids with intense
agitation and subsequent utilization of a stabilizer
[13 6]. The disadvantages of these methods consist
in complexity of a process, difficulty in obtaining
a narrow size distribution of particles, and necessity
of additional operations to prevent subsequent ag-
Here we suggest an electrochemical method of
preparation of a CdTe semiconductor compound with
a grain size of 335 nm. The advantages of the electro-
chemical method are that it allows control of synthesis
parameters through change in electrochemical param-
eters, uses simple equipment, and involves complex
formation with heterocyclic amines for stabilizing
ultradispersed aggregates, which allows preparation of
stable metal colloid systems.
Acid electrolytes (pH 032) are widely used for
electrochemical deposition of CdTe films .
However, previous studies  demonstrated the
possibility of using ammonia3chloride buffer electro-
lytes. This made it possible to improve properties of
the formed films by decreasing the amount of ele-
mental tellurium codeposited with CdTe, to increase
the electrodeposition rate, and to prevent corrosion.
This study is concerned with electrodeposition of
the CdTe films from ammonia3chloride buffer elec-
trolytes containing 2,2`-bipyridine. The effect of the
grain size of films on the volt3ampere characteristics
of CdTe semiconductor under illumination was
The electrochemical processes occurring on a
glassy carbon electrode upon deposition of CdTe were
studied by voltammetry. The composition and proper-
ties of the deposits obtained were investigated by
physical methods. These involved XPA, electron
microscopy, and electron probe analysis. Also, the
optical volt3ampere characteristics taken on a Z-curve
tracer upon scattered illumination were analyzed.
As electrolyte we used ammonia3chloride buffer solu-
tions with pH 8.4 and 9.2, ionic strength m = 2, and
high buffer capacity p = 0.4, which virtually elimi-
nated variations of pH in a near-electrode layer in
the case of discharge of both molecular oxygen and
Te(IV) anions (TeO
). The volt3ampere
curves were measured in a three-electrode Pyrex glass
cell with separated cathode and anode compartments.
As working electrode we used a glassy carbon elec-
trode with an apparent surface area of 0.07 cm
auxiliary electrode served a platinum electrode with
an apparent surface area of 1.5 cm
. The potentials
were measured relative to a silver chloride reference
electrode in a saturated potassium chloride solution.
The voltammetric studies were performed using a PI-
50.1.1 potentiostat, with I!E curves recorded with
a PDA-1 XY recorder.
The cathodic volt3ampere curve obtained in a solu-
tion containing 3.80 10
M Te(IV) (Fig. 1a) shows
a region of limiting current, which is due to the reduc-