Recent Advances In High Resolution X-Ray Diffraction Studies
Of Semiconductors For Technological Applications
Krishan Lal
National Physical Laboratory
Dr. K.S. Krishnan Road
New Delhi - 110012
ABSTRACT
Basic principles of high-resolution X-ray diffraction techniques and essential
features of a five-crystal X-ray diffractometer developed in author’s
laboratory have been described.
Illustrative examples include direct
observation of large strain fields around dislocations in nearly perfect
gallium arsenide single crystals and relationship between oxygen content
and perfection of silicon single crystals. It has been possible to characterize
thin epitaxial film of SiGe (40 nm thick) by using normal incidence highresolution x-ray diffractometry.
Introduction
Bulk crystals and thin films of semiconductor materials are widely being employed in a
wide variety of microelectronic and optoelectronic devices.
Also, for fundamental
understanding of semiconductors, it necessary to establish a relationship between properties
and traces of impurities and defects like dislocations and point defects. It is necessary to
have stringent control on elemental composition and real structure of crystals as these are
subject to processing steps for fabrication of devices. Advanced techniques are available
for diagnostic purposes. High-resolution X-ray diffraction (HRXRD) techniques have been
1
widely employed to evaluate the quality of raw single crystal wafers (crystallinity,
perfection, orientation and surface preparation) [1-3]. For epitaxial films one can in
addition determine lattice mismatch with respect to the substrate wafers and from it their
chemical composition. The nondestructive character of HRXRD techniques makes them
particularly effective in evaluation of crystals at different stages of processing. Practically
all types of defects including boundaries, dislocations, clusters of point defects and isolated
point defects can be investigated by employing these techniques. In addition, non-localized
defects like biaxial stress in thin film - single crystal substrate systems can be determined
[4-7]. This paper describes essential features of HRXRD techniques and some recent
experimental results.
High Resolution X-ray Diffraction
The following two theories of X-ray diffraction from crystals are widely used
[8-
11]: (i) the kinematical theory; and (ii) the dynamical theory. The first theory is rather
approximate but widely used for investigating problems connected with ideal structure of
crystals. The dynamical theory of X-ray diffraction is widely employed for study of nearly
perfect crystals [3, 8-11]. This is a rigorous theory and enables determination of the shape
of diffraction curves, understanding anomalous transmission of X-rays through crystals
during Laue diffraction and pendellosung phenomenon. According to the dynamical theory
the diffraction curves of an ideally perfect crystal should have half widths of a few arc sec.
The reflectivity at the diffraction maximum can be nearly 100%. To realize these features
in actual experiments it is necessary to improve the quality of X-ray beams employed in
normal X-ray diffraction experiments. The angular divergence and wave length spread (in
terms of angle) of the exploring X-ray beam should be less than 1 arc sec. X-ray diffraction
with such beams is termed as high resolution X–ray diffraction (HRXRD).
To produce nearly parallel and monochromatic X-ray beams one employs X-ray
diffraction from nearly perfect crystals like those of silicon.
The angular range of
diffraction for perfect crystals is limited to a few arc sec, as we had mentioned above.
Therefore, such crystals select only a narrow range of angles from the incident beam in a
diffraction experiment. By combining a few monochromators, it is possible to achieve high
2
quality X-ray beam with reasonable intensity.
A wide variety of multi-crystal X-ray
diffractometer have been developed to achieve high resolution in X-ray diffraction
experiments [1-3, 12]. In author’s laboratory a series of diffractometers have been
developed and fabricated for a variety of experiments. These include a five-crystal X-ray
diffractometer with state-of-the-art level resolution.
Fig. 1 shows a schematic line diagram of the five crystal X-ray diffractometer
designed, developed and fabricated in author’s laboratory [2,12]. The X-ray beam emerging
from a fine focus X-ray source is collimated with the help of a specially designed
collimator, which is positioned for a foreshortening of ~3°.
The collimator has two sets of
fine slits one of these is vertical and perpendicular to the plane of diffraction. This restricts
the divergence of the X-ray beam to ~80 arc sec in the plane of diffraction. The collimated
beam falls on a set of two plane silicon monochromator crystals of Bonse- Hart type [13].
The diffracting surfaces of these monochromators are along (1 1 1). When these are
oriented for diffraction one gets well resolved Kα1 and Kα2 X-ray beams. The Kα1 beam is
isolated with the help of another collimator, which stops the residual direct beam and the
Kα2 component. The Kα1 beam is further diffracted from a plane silicon monochromator
having its diffracting surface along (1 0 0). The third monochromator is oriented for
diffraction from (8 0 0) set of planes. This highly dispersive geometry leads to a substantial
reduction in the divergence and the wavelength spread of the X-ray beam. This beam is
generally employed as the exploring X-ray beam. The specimen is mostly the fourth
crystal of the diffractometer. It can be oriented in the Bragg or the Laue geometries. The
beam diffracted from the specimen is further diffracted from an analyzer crystal. The
analyzer crystal is very useful when changes in lattice parameter of the specimen due to
externally applied electric field are to be determined or mismatches between epitaxial films
and substrate crystals are to be determined precisely. The design of the diffractometer is
such that the specimen can occupy any position depending upon the requirements of the
experiments to be performed.
The five-crystal X-ray diffractometer can be employed for making the following
HRXRD experiments: (i) diffractometry; (ii) topography; (iii) diffuse X-ray scattering
measurements; (iv) measurements of curvature of wafer
3
- thin film systems for
determination of biaxial stress; (v) precise determination of lattice parameters of crystals
and thin films, (vi) determination of lattice and orientational mismatches between epitaxial
films and substrate single crystals; and (vii) determination of orientation of crystal surfaces
and flats on single crystal wafers.
It can also be used for accurate measurement of
absorption coefficient of crystals for X-rays including study of anomalous transmission of
X-rays during Laue diffraction. Experiments like diffractometry can be controlled with the
help of a PC.
Fig. 2 shows a typical diffraction curve of a nearly perfect silicon crystal recorded
with the five-crystal X-ray diffractometer [2]. This curve was recorded with (1 1 1) planes,
which are nearly parallel to the surface of the specimen. For comparison, we show in Fig.
3 a theoretical diffraction curve obtained by using the dynamical diffraction theory in the
plane wave approximation [2]. It can be seen that the half width of the experimental curve
is larger than that of the theoretical curve by only 0.3 arc sec. Also, the experimental curve
shows nearly 100% reflectivity at the peak (Fig.2).
Therefore, we can see that the
experimental curve is very close to the theoretical diffraction curve. These features are
indications of high resolution that can be achieved by employing such a system. The author
and his colleagues have carried out a variety of investigations by employing this and the
other multi-crystal diffractometers.
Some recent results will be summarized in the
following.
Characterization of Defects in Semiconductor Crystals
X-ray diffraction topography is widely used for direct observation and
characterization of dislocations in nearly perfect crystals.
Multi-crystal X-ray
diffractometers are well suited to image the large strain field around dislocations in nearly
perfect crystals. We shall describe a typical example of characterization of dislocations in
gallium arsenide crystals [6]. Fig. 4 shows a typical high-resolution traverse topograph of a
(1 0 0) GaAs crystal, which was grown by the horizontal Bridgman method. Three images
of dislocations are observed in the entire volume of the crystal. The size of each image is
very large, extending to ~ 1 mm. This shows that HRXRD techniques are very sensitive to
4
strain field covering a large region around the defects. Also, one can see that in the top
right-hand corner, a small region is not diffracting. A very small tilt of a few arc sec is
responsible for it. It may be mentioned that the half-width of diffraction curve of this
particular specimen was ~ 10 arc sec. The specimen was maintained at the peak of the
diffraction curve as it was traversed across the X-ray beam for recording the topographs.
Defects structure in a variety of crystals has been investigated in authors laboratory.
This includes silicon, gallium arsenide, CdTe, GaSb, lithium niobate, BGO, diamond,
saphire, garnets and others. In the case of silicon it is rather rare to find a dislocation.
However, characterization of point defect clusters and isolated point defects in dislocation
free crystals is an area of considerable importance. Further, interesting microstructure can
be observed on application of high electric fields to these crystals [2].
It is well known that X-ray diffractometery and topography techniques can not be
directly employed for study of point defects and their clusters. The author and his coworkers have employed high-resolution diffuse X-ray scattering (DXS) measurements for
study of these defects in nearly perfect crystal [14-23]. It has been shown that silicon
crystals grown by the two widely employed techniques, namely the Czochralski (CZ) and
the floatzone (FZ) methods contain different types of point defects [15,19]. It has been
shown that in the crystals grown by the CZ method the dominant contribution to DXS is
from defects of interstitial type. In the FZ grown crystals on the other hand the dominant
defects were of vacancy type. A phenomenological model has been successfully employed
to analyze the DXS data for obtaining essential parameters of the defects [24].
This model
is based on the assumption that he defects are loosely clustered point defects. Typical
values of radii of vacancy clusters in FZ crystals were 0.6 μm [18]. For CZ crystals, the
cluster size was obtained as 0.8 m [19]. It has been shown that the DXS distribution is
very sensitive to the thermal history of the specimen and the nature of treatment it has
undergone during various processing steps for device fabrication. Control of oxygen level
in FZ grown silicon crystals can produce remarkable changes in the point defects. The
essential results of a recent study are described in the following.
A comparative study of defects in silicon crystals grown by the FZ as well as the
CZ methods had yielded interesting results [21,22]. It was found that the FZ crystals, which
5
contain lower concentration of oxygen than the CZ crystals have slightly lower degree of
perfection than the CZ crystals [15,21].
It may be mentioned that somewhat similar
relation is to known in the case of type I and type II natural diamond crystals [26]. The
perfection of type I diamond crystals, which contain appreciable concentration of nitrogen
is higher than that of the type II diamonds which are relatively free of nitrogen. We have
investigated the effect of oxygen content on the degree of perfection of FZ grown silicon
crystals [21,22].
For study of effect of oxygen concentration on crystalline perfection of FZ crystals
we had selected high purity silicon crystals characterized by electrical resistivity of  10
kcm [20]. Oxygen was introduced by heating this specimen under oxygen at different
temperatures (from room temperature 1100C.). The concentration of oxygen was
monitored by using infrared absorption measurement around 1105 cm-1 by employing a
FTIR spectrophotometer [27]. It was found that a marginal increase in oxygen content
starts taking place after annealing the specimen at 873 K and higher temperature.
Annealing at 1073 K produced an increase in oxygen concentration from 1.3 × 1017 cm-3
(no heat treatment) to
3.6 × 1017cm-3. It may be mentioned that good quality CZ grown
crystals have about this concentration of oxygen. Annealing at higher temperatures led to
further increase in the oxygen concentration. For example, those specimen which were
annealed at 1373 K the oxygen concentration reached 1.7 × 1018 cm-3 However, a shift in
the wavelength of the infrared absorption band was observed which, suggested
agglomeration of oxygen. This was confirmed by diffuse X-ray scattering measurements
described below.
High resolution X-ray diffractometery and high resolution diffuse X-ray scattering
(DXS) measurements were made after each annealing step described above. The half
widths of the diffraction curves of (111) lattice planes of these specimen crystals were  11
arc sec to begin with. The absolute value of the integrated intensity
10-5 rad.
The DXS intensity distribution was typical of FZ grown silicon crystals indicating
dominant contribution of vacancy type defects. The change in real structure was negligible
up to annealing temperature of 873 K. Remarkable changes were observed for annealing
6
temperatures lying between 873 K and 1073 K. Fig. 5 shows a set of three diffraction
curves recorded before annealing, after annealing at 1073 K and after annealing at 1373 K.
The half widths of diffraction curve decreased from 11 arc sec, to 7 arc sec after annealing
at 1073 K. Further annealing at 1373 K led to the broadening of the diffraction curve and
the half width increased to 10.5 arc sec, showing a deterioration in the perfection of the
crystals. The results of absolut
10-5 rad. after
 10-5
-5
rad. Further, the v
rad after annealing at 1373 K. This
experiment indicates a direct co-relation between the concentration of oxygen in silicon and
its crystalline perfection. The perfection is maximum when the oxygen level is about 4 x
1017 cm-3 (obtained after annealing at 1073 K), which is typical of high quality CZ crystals.
Fig. 6 shows a typical set of four DXS intensity vs. K* plots. These were recorded
at the following stages: before annealing, after annealing at 873 K, after annealing at 1073
K and after annealing at 1373 K. Here K* is a vector, which joins the elemental volume of
the reciprocal space under investigation to the nearest reciprocal lattice point. In this
figure, we show only those plots in which K* is along the reciprocal lattice vector R*. The
point defect cluster in this crystal could be modelled as platelets lying of (1 1 1) plane.
Therefore, for the sake of clarity, plots with K* along [1 11 ] {curve (a)} and [1 1 1]
{curve (b), and (d)} are shown in this figure. The experimental data is shown as discrete
points. The phenomenological model was used to analyze the experimental data [24]. The
lines in Fig 6 were obtained by employing the model proposed by Dederichs. The fit
between the experimental points and the theoretical curves is quite good. In the as grown
state, the DXS data showed the dominance of the isolated vacancies and their clusters. The
cluster size was ~ 0.2 m. A comparison of curves (a) and (b) shows that there is an over
all decrease in the DXS intensity on annealing, showing an improvement in the degree of
perfection. Also, a small decrease in cluster size has taken place (from 0.24 m to 0.22
m). The most remarkable change is observed in curve (c). The entire curve is a single
straight line with a slope of – 2. The sign of the anisotropy in DXS distribution has
7
changed to positive, from the negative sign observed in the as grown specimen. The
change in the sign of the anisotropy indicates the dominance of interstitial point defects,
which may be oxygen impurity atoms.
It may be noted that after annealing at this
temperature the crystals had shown remarkable improvement in the degree of perfection. In
curve (d) we can see two well defined regions in DXS plots with slopes of –2 (at low values
of K*) and –4 (at higher values of K*). This indicates clustering of interstitial defects after
annealing 1373 K.
The size of the interstitial clusters was found to be ~ 0.8 m.
urements and
analysis of DXS distribution has clearly shown that the enhancement in the degree of
perfection of silicon crystals is linked with the oxygen concentration in silicon crystals. An
oxygen concentration of ~ 4 x 1017 cm-3 without segregation is optimum for achieving high
degree of crystalline perfection.
Structural Characterization of Thin Epitaxial Films
Thin films of a wide of variety of materials are extensively employed in all most all
devices. It is a challenge to unravel the real structure of these films when one or more of
their dimensions are restricted to very smaller values, in nanometer range. X-ray
diffractometery, particularly, in grazing incident mode has been quite widely used [28].
Even the normal high resolution X-ray diffractometery can give valuable of information
about epitaxial films regarding crystallinity, structural quality, lattice and orientational
mismatches between films and substrates and the biaxial stress in such system. A wide
variety of films have been investigated in the author’s laboratory. These include MBE
grown structures of InAlAs, InGaAs, SiGe, CdTe, GaSb and films grown by other
techniques like those of silicon oxide, silicon nitride, polysilicon, silicon oxinitride and Mosilicide on silicon [6, 7, 29-35]. Biaxial stress in multi-level metallizations on GaAs
substrates had been investigated in details. One typical result of structural characterization
of MBE grown SiGe films is reported in this following [30].
Fig. 7 shows a typical high resolution X-ray diffraction curve of a 40 nm thick MBE
grown SiGe film. It can be seen that a very well defined diffraction peak could be obtained
8
by employing normal incidence diffraction, even though the thickness of this film is very
small. From the observed angular separation between the diffraction peaks of the film and
the substrate the value of the lattice mismatch
composition was deduced as Si82.4Ge17.6. It needs to be emphasized that if one obtains the
erved angular separation between the diffraction
The lattice mismatch is not the only mismatch between the lattice planes of the epitaxial
film and those of the substrate. In general, the lattice planes of the film and substrate are
not parallel to each other. There is a finite angle between the two. Therefore, the observed
angular separation between the diffraction peaks of the film and the substrate crystal is a
function of both
is ignored, the values of chemical composition of the films may be in serious error. By
employing the analyzer crystal of the diffractometer the value of both the mismatches can
be determined precisely. In some of the highly mismatched thin films, like MBE grown
GaSb films on GaAs, the mismatch is very large [31]. The angular separation between the
film and the substrate peaks is ~ 1 arc deg. In such situations, it is not feasible to use the
analyzer crystal for determination of mismatches. One studies the variations in angular
separation between the two peaks as a function of the azimuthal rotation of the specimen in
its own plane. The angular separation shows periodic variation with azimuthal rotation. By
analyzing this data one can determine the values of both the mismatches.
Conclusions
In this paper we have briefly described the fundamental principles of high resolution Xray diffraction techniques, a five-crystal X-ray diffractometer developed in author’s
laboratory and their application in study of bulk crystals and thin films. The following
typical experimental results have been described as illustrative examples:
(i)
characterization of dislocations in nearly perfect GaAs crystals;
9
(ii)
study of influence of oxygen on crystalline perfection of silicon single crystals;
and
(iii)
structural characterization of silicon germanium films.
Acknowledgements
The author had the privilege and pleasure of collaborating with a number of
colleagues and students in his laboratory and with a number of distinguished scientists from
India and abroad. Collaborative research with the following colleagues is particularly
acknowledged: Drs. Niranjana Goswami, G. Bhagavannarayana, R.R. Ramanan and Prof.
H.L. Hartnagel. A part of this work was supported under an Indo-US project coordinated
by the Department of Science and Technology, New Delhi and a part of the work was
carried out under an Indo-German project coordinated by Council of Scientific and
Industrial Research, New Delhi.
References
1. D. Keith Bowen and B.K. Tanner, High Resolution X-ray Diffractometry and
Topography, Taylor and Francis Ltd., London EC4A 3DE (1998).
2. Krishan Lal, Proc. Ind. Nat. Sci. Acad. 64A, (1998) 609-635.
3. Z. G. Pinsker, Dynamical Scattering of X-rays in Crystals, Springer-Verlag, Berlin,
(1978).
4. G.A. Rozgonyi and T.J. Ciesielka, Rev. Sci. Instrum. 44 (1973) 1053-1057.
5. A. Segmuller, I.C. Noyan and V.S. Speriosu, Prog. Crystal Growth Charact. 18
(1989) 21
6. Krishan Lal, S. Niranjana N. Goswami J. Wurfl and H.L. Hartnagel, J. Appl. Phys.
67, (1990) 4105-4113.
7. Krishan Lal,
Reshmi
Mitra, G. Srinivas and V. D. Vankar, J. Appl. Cryst. 29
(1996) 2-10.
10
8. W.H. Zachariasen, Theory of X-ray Diffraction in Crystals, Wiley, New York
(1945).
9. M. Von Laue,
Rontegenstrahlininterferennzen, Acad. Verlagsgescllschaft,
Frankfurt, (1960).
10. B.W. Batterman and H. Cole, Rev. Mod. Phys. 36 (1964) 681-717.
11. Andre Authier, Dynamical Theory of X-ray Diffraction, Oxford University Press,
Oxford (2001)
12. Krishan Lal, Bull. Mater. Sci. 16 (1993) 617-642.
13. U. Bonse and M. Hart, Appl. Phys. Lett. 7 (1965) 238-239.
14. Krishan Lal, Prog. in Crystal Growth Charac. 18 (1989) 227-266
15. Krishan Lal and G. Bhagavannarayana, J. Appl. Cryst. 2 (1989) 209-215.
16. Krishan Lal, G. Bhagvannarayana and G. S. Virdi, J. Appl. Physics 69 (1991) 80928095.
17. Krishan Lal, G. Bhagavannarayana and G. S. Virdi, Solid State Phenomena 47-48
(1996) 377-382.
18. G. Bhagavannarayana, Ph. D. Thesis, University of Delhi, Delhi, (1994).
19. R.R. Ramanan, G. Bhagavannarayana and Krishan Lal, J. Crystal Growth 156 (1995)
377-382
20. R.R. Ramanan, S. Niranjana N. Goswami and Krishan Lal, Acta Cryst. A54 (1998)
163-171.
21. Krishan Lal, R.R. Ramanan and G. Bhagavannarayana, J. Appl. Cryst., 33 (2000)
2-9.
22. R. R. Ramanan, Ph. D. Thesis, University of Delhi, Delhi, (1998).
23. R.V. Anantha Murthy, M. Ravikumar, A. Choubey, Krishan Lal, Lyudmila
Kharachenko, V. Shleguel, V. Guerasimov, J. Crystal Growth, 197 (1999) 865-873.
24. P. H. Dederichs, J. Phys. F 3 (1973) 471; Phys. Rev. B4 (1971) 1041.
25. G. Bhagavannarayana, A. Choubey, Yu. V. Shubin, and Krishan Lal, Acta Cryst. (to
be published).
26. G. Davies , Diamond, London: Adam Hilger (1984).
11
27. ASTM, Annual Book of the American Society for Testing Materials Standards,
F1221-80, (1980) 538-540.
28. S.A. Stepanov, E.A. Kondrashkina, M. Schmidbauer, R. Koehler, J. –U. Pfeiffer, T.
Jach, and A. Yu. Souvorov, Phys. Rev. B, 54 (1996) 8150-8162.
29. Krishan Lal in Semiconductor Devices, Krishan Lal (Ed.), Narosa Publishers, New
Delhi, (1995), 243-252.
30. M. Mukhopadhyay, L.K. Bera, S.K. Ray, S.N. Sahu, B.R. Mehra, N. Goswami,
Krishan Lal and C.K. Maiti, IETE Journal of Research, 43 (1997) 155-163.
31. S. Niranjana N. Goswami, Krishan Lal, A. Vogt and H. L. Hartnagel, (to be
published).
32. S.K. Halder, Vijay Kumar, Krishan Lal, P. Suryanarayana, B.B. Dixit and P.D.
Vyas in Physics of Semiconductor Devices, Krishan Lal (Ed.), Narosa Publishers,
New Delhi (1994) 337-339.
33. S.K. Halder, Vijay Kumar, Krishan Lal, Vipan Kumar and O.P. Agnihotri in
Physics of Semiconductor Devices, Krishan Lal (Ed.), Narosa Publishers, New
Delhi (1994) 340-342.
34. S. Niranjana N. Goswami, Krishan Lal, R. Kothari and Y. K. Bhatnagar in
Semiconductor Devices, Krishan Lal (Ed.), Narosa Publishers, New Delhi (1996)
382-384
35. S. Niranjana N. Goswami, Krishan Lal, J. Wurfl and H.L. Hartnagel in Physics of
Semiconductor Devices, Krishan Lal (Ed.), Narosa Publishers, New Delhi, (1994)
337-339.
12
MonochromatorCollimator 1
X-ray Source
MonochromatorCollimator 3
K2
K1
K1
Slit 1
Analyser
Crystal
MonochromatorCollimator 2
Slit 2
Specimen
Detector
Fig. 1
A schematic line diagram of the Five Crystal X-ray Diffractometer designed,
developed and fabricated at author’s laboratory.
13
(111) Silicon Crystal Specimen;
(111) Diffracting Planes;
Mo K Radiation;
(+,-,+,-,(+)) Configuration.
Half Width: 3.7 arc sec

Fig. 2 A high resolution X-ray diffraction curve of a (111) silicon single crystal
recorded on the Five Crystal X-ray Diffractometer. Symmetrical Bragg
geometry, (+, -, +, -, +) configuration of the diffractometer, and Mo K1
exploring beam were employed. The points represent the as measured data
without any corrections being applied.
14
0.9
Reflectivity EH2 / E02
20
/E
2H
Re
fle
ctiv
ity
E
0.8
0.7
0.6
0.5
Half Width: 3.43
arc sec
0.4
0.3
0.2
0.1
0
10
5
0
-5
-10
-15
Deviation From Bragg Angle , arc sec
Fig. 3 A theoretical diffraction curve calculated on the basis of plane
wave dynamical theory for an ideally perfect silicon crystal for
experimental conditions of Fig 2.
15
g [220]
2mm
Fig. 4 A HRXRD traverse topograph of a nearly perfect gallium
arsenide crystal recorded in symmetrical Laue geometry
with Mo K1 radiation. Only three dislocations are
observed in the entire volume of the wafer.
16
35
b Annealing Temperature, A T
o
600 C
o
800 C
2
Diffracted X-ray Intensity, 10 c/s
30
o
25
1100 C
20
7 arc sec
10.5 arc sec
15
11 arc sec
10
5
c
a
0
-60
-40
-20
0
20
40
60
Glancing Angle  , arc sec
Lal, Ram anan, and Bhagavannarayana, J. Appl. Cryst. (1999), in press
Fig. 5 Typical diffraction curves of a nearly perfect single crystal
of silicon. Mo K1 radiation, symmetrical Bragg geometry
and (+, -, +, -) configuration of the diffractometer were
employed. (a), (b) and (c) were recorded after annealing the
specimen at 873 K, 1073 K and 1373 K, respectively.
17
Fig. 6 A set of typical log [DXS intensity I/I0] vs. log K* plots
for a silicon crystal grown by the FZ method. (a), (b), (c)
and (d) are respectively for as grown state and after
annealing at 873 K, 1073 K and 1373 K. Other
experimental conditions were the same as in Fig. 6.
18
MBE Grown SiGe Epitaxial Film
25
400 Relp; Mo K1
Film thickness: 40 nm
20
Film Composition: Si
82.4
Ge
17.6
15
10
5
0
-900
-800
-700
-500
-600
Glancing Angle , arc sec
-400
Fig. 7 A typical high resolution X-ray diffraction curve of a 40 nm thick
silicon-germanium film grown by molecular beam epitaxy on a (100)
silicon substrate. Mo K1 radiation, (+, -, +, -) configuration of the
diffractometer and symmetrical Bragg geometry were employed.
19