ISSN 1063-7834, Physics of the Solid State, 2006, Vol. 48, No. 4, pp. 631–636. © Pleiades Publishing, Inc., 2006.
Original Russian Text © N.R. Grigor’eva, R.V. Grigor’ev, B.V. Novikov, A.V. Ankudinov, M.S. Dunaevskiœ, A.N. Titkov, D. Hirsch, J. Lenzner, V.F. Agekyan, T. Komatsu, 2006,
published in Fizika Tverdogo Tela, 2006, Vol. 48, No. 4, pp. 591–596.
631
1. INTRODUCTION
The surface morphology of various semiconductor
structures can be successfully studied by atomic force
microscopy (AFM), which makes it possible to reveal
and characterize various surface micro- and nanoob-
jects that appear under certain technological condi-
tions. AFM can be used to analyze the self-organization
of quantum dots on the surfaces of binary II–VI com-
pounds and their solid solutions and the effect of atmo-
spheric conditions on the surface morphology. For
example, AFM has been used to investigate the natural
faces of CdSe [1]. In [2], the surface morphology of
self-organized CdSe quantum dots grown by MBE on a
ZnSe substrate was examined. In [3], the effect of atmo-
spheric conditions on the parameters and dynamics of
individual Cd(Zn)Se nanoislands was studied. The
dynamics of nanocluster formation on the surfaces of
CdTe and ZnSe epitaxial films was investigated in [4–
6]. The investigation performed in [7] of the effect of a
stress distribution in the volume of InGaAsP/InGaP
heterostructures on their surface morphology is also of
interest.
2. EXPERIMENTAL
We examined the natural faces of CdS
1 – x
Se
x
solid-
solution crystals (0.15 < x < 0.50). The crystals were
grown by sublimation from a gas phase. A charge mate-
rial was evaporated at T = 1250 K, and condensation
was carried out at T = 1100 K. The cooling time of the
reactor was 24 h, and the cooling rate in the temperature
range 900–1250 K was 3 K/min. Before examination,
the crystals were stored under atmospheric conditions.
Their surface relief was analyzed over three years. This
relief remained unchanged over time; that is, the sur-
face was stabilized. A chemical analysis of the near-
surface layers in some samples revealed carbon and
oxygen adsorbed from the atmosphere. Surface studies
were performed with modern atomic force microscopes
at the Ioffe Physicotechnical Institute (St. Petersburg,
Russia), the Institute of Surface Modification (Leipzig,
Germany), and Osaka City University (Osaka, Japan).
The device for cathodoluminescence detection was
based on a CamScan CS 44 scanning electron micro-
scope. The electron energy was varied from 5 to
20 keV, the current was 800 pA, the lateral resolution of
the method used was 1 μm, and the penetration depth of
the electron beam was varied from 0.1 to 5.0 μm. The
radiation-recording system covered the range 350–
950 nm at a resolution of 0.5 nm. With this device, we
plotted radiation-intensity maps for a surface at a fixed
wavelength and recorded the cathodoluminescence
spectra from various regions of the surface at 10 K. We
could simultaneously examine a surface relief using
secondary electron emission and perform an electron
microprobe analysis of the chemical composition of the
region under study.
SEMICONDUCTORS
AND DIELECTRICS
Morphology of the Stabilized Natural Faces
of a CdS
1 – x
Se
x
Solid Solution
N. R. Grigor’eva
a
, R. V. Grigor’ev
a
, B. V. Novikov
a
, A. V. Ankudinov
b
, M. S. Dunaevskiœ
b
,
A. N. Titkov
b
, D. Hirsch
c
, J. Lenzner
d
, V. F. Agekyan
a, e
, and T. Komatsu
e
a
St. Petersburg State University, Ul’yanovskaya ul. 1, St. Petersburg, 198504 Russia
e-mail: N.Grigorieva@pobox.spbu.ru
b
Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021 Russia
c
Institute of Surface Modification, Leipzig, D-04318 Germany
d
Leipzig University, Leipzig, 04103 Germany
e
Osaka City University, Sugimoto-cho, Sumiyshi-ku, Osaka, 558 Japan
Received July 1, 2005
Abstract—The morphology of the stabilized surfaces of CdS
1 – x
Se
x
crystals exposed to air at room tempera-
ture is studied by atomic force microscopy. The characteristic features of the relief of the natural faces of these
crystals are described, and the causes of the appearance of these features are discussed. The morphological
results are related to the results of the microcathodoluminescence study of surface micro- and nanostructures.
This study revealed objects that contribute to exciton emission and, hence, are CdS
1 – x
Se
x
solid solutions.
PACS numbers: 68.37.Ps, 68.35.Bs
DOI: 10.1134/S1063783406040044