Influence of ion implantation and annealing on composition and structure of GaAs surface
In this work investigated is the influence of barium ion implantation and subsequent annealing on composition, electronic and crystalline structure of GaAs surface. For the first time, the influence of low energy Ba⁺ ions implantation on the structure of GaAs surface was investigated using photoelec...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
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Normuradov, M.T. Umirzakov, B.E. Tashmukhamedova, D.A. Tashatov, A.K. 2017-06-13T16:39:22Z 2017-06-13T16:39:22Z 2002 Influence of ion implantation and annealing on composition and structure of GaAs surface / M.T. Normuradov, B.E. Umirzakov, D.A. Tashmukhamedova, A.K. Tashatov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2002. — Т. 5, № 2. — С. 138-141. — Бібліогр.: 9 назв. — англ. 1560-8034 PACS: 61.72.V, 61.80.-x, 79.60.-i https://nasplib.isofts.kiev.ua/handle/123456789/121184 In this work investigated is the influence of barium ion implantation and subsequent annealing on composition, electronic and crystalline structure of GaAs surface. For the first time, the influence of low energy Ba⁺ ions implantation on the structure of GaAs surface was investigated using photoelectron spectroscopy. Determined are parameters of energy bands and the crystalline lattice of the three-component system Ga₀.₆Ba₀.₄As. The width of the forbidden gap is Eg = 1 eV, the lattice constant is a = 5.73 Å. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Influence of ion implantation and annealing on composition and structure of GaAs surface Article published earlier |
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Influence of ion implantation and annealing on composition and structure of GaAs surface |
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Influence of ion implantation and annealing on composition and structure of GaAs surface Normuradov, M.T. Umirzakov, B.E. Tashmukhamedova, D.A. Tashatov, A.K. |
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Influence of ion implantation and annealing on composition and structure of GaAs surface |
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Influence of ion implantation and annealing on composition and structure of GaAs surface |
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Influence of ion implantation and annealing on composition and structure of GaAs surface |
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Influence of ion implantation and annealing on composition and structure of GaAs surface |
| title_sort |
influence of ion implantation and annealing on composition and structure of gaas surface |
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Normuradov, M.T. Umirzakov, B.E. Tashmukhamedova, D.A. Tashatov, A.K. |
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Normuradov, M.T. Umirzakov, B.E. Tashmukhamedova, D.A. Tashatov, A.K. |
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2002 |
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English |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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In this work investigated is the influence of barium ion implantation and subsequent annealing on composition, electronic and crystalline structure of GaAs surface. For the first time, the influence of low energy Ba⁺ ions implantation on the structure of GaAs surface was investigated using photoelectron spectroscopy. Determined are parameters of energy bands and the crystalline lattice of the three-component system Ga₀.₆Ba₀.₄As. The width of the forbidden gap is Eg = 1 eV, the lattice constant is a = 5.73 Å.
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1560-8034 |
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https://nasplib.isofts.kiev.ua/handle/123456789/121184 |
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Influence of ion implantation and annealing on composition and structure of GaAs surface / M.T. Normuradov, B.E. Umirzakov, D.A. Tashmukhamedova, A.K. Tashatov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2002. — Т. 5, № 2. — С. 138-141. — Бібліогр.: 9 назв. — англ. |
| work_keys_str_mv |
AT normuradovmt influenceofionimplantationandannealingoncompositionandstructureofgaassurface AT umirzakovbe influenceofionimplantationandannealingoncompositionandstructureofgaassurface AT tashmukhamedovada influenceofionimplantationandannealingoncompositionandstructureofgaassurface AT tashatovak influenceofionimplantationandannealingoncompositionandstructureofgaassurface |
| first_indexed |
2025-11-26T20:20:49Z |
| last_indexed |
2025-11-26T20:20:49Z |
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1850773164678709248 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2002. V. 5, N 2. P.138-141 .
© 2002, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine138
PACS: 61.72.V, 61.80.-x, 79.60.-i
Influence of ion implantation and annealing
on composition and structure of GaAs surface
M.T. Normuradov1), B.E. Umirzakov2), D.A. Tashmukhamedova2), A.K. Tashatov1)
1)Karshin Engineer-and-economics
2)Tashkent State Technical University
E-mail: ftmet@rambler.ru
Abstract. In this work investigated is the influence of barium ion implantation and subse-
quent annealing on composition, electronic and crystalline structure of GaAs surface. For the
first time, the influence of low energy Ba+ ions implantation on the structure of GaAs surface
was investigated using photoelectron spectroscopy. Determined are parameters of energy
bands and the crystalline lattice of the three-component system Ga0.6Ba0.4As. The width of the
forbidden gap is Eg = 1 eV, the lattice constant is a = 5.73 Å.
Keywords: ion-implantation, photoelectron spectroscopy, post-implantation annealing.
Paper received 29.03.01; revised manuscript received 03.06.02; accepted for publication 25.06.02.
1. Introduction
From the viewpoint of creation of solar cells, integrated
circuites, optoelectronic and integrated-optical systems,
it is very important to obtain new multi-component thin-
film structures grown on surfaces of each other. In par-
ticular, criteria of applicability of solar cells in cosmic
energetics are as follows: high efficiency of solar energy
transformation and stability to radioactive emission. In
this respect, special interest presents creation of periodic
and layered systems with variable composition based on
GaAs films.
One of the efficient methods to obtain these structures
is the low energy ion implantation. Many works [1�4]
were aimed to study the influence of ion implantation on
condition and properties of solid surface. These investi-
gations showed that low energy ion bombardment, re-
sults in improvement of emission efficiency of material,
promotes low-temperature epitaxial growth of films from
ion-molecular beams, allows to get passivating,
anticorrosive and other coatings [3,4,8]. There were also
obtained reliable data about formation of the chemical
bonds between atoms of matrixes and an implanted ele-
ment, about degrees of surfaces disorder, about changes
of positions intrinsic to maxima of valent electron den-
sity states [3,4,9]. However, taking into account the defi-
ciency of the systematic researches using the most informa-
tive methods of surface diagnostics, a whole series of ques-
tions, related to changes of the electronic states, atomic
structure and mechanisms of new phase formation were
not ascertained so far. In particular, there was practi-
cally absent reliable information about the form and struc-
ture of the electronic density-of-state spectrum and about
the nature of features observed in these spectra for crys-
tals, implanted by low energy ions (Å0 ≤ 10 keV) and
subjected to the following annealing.
In this work, investigated was the effect of barium
ions implantation and of the subsequent annealing on
composition, electronic and crystalline structures of GaAs
surface.
2. Experimental
The technological treatment (ion-implantation, an-
nealing), the investigation of the structure and proper-
ties of samples were carried out in the same high vacuum
(P ≤ 10�7 Pa) experimental device. The experimental de-
vice and measurement procedure were described in de-
tails earlier [4]. A change of the surface crystalline struc-
ture were studied by high-energy electron diffraction
(HEED) using a standard device of the EMR-2 type.
M.T. Normuradov et al.: Influence of ion implantation and annealing...
139SQO, 5(2), 2002
For carrying out implantation of barium ions, used
was the construction of gun based on the principle of sur-
face ionization [5]. BaTi tablets were used as an ion
source. The ion guns contain the following main parts:
ion source, accelerating and focusing electrodes, sepa-
rator of ions on masses. The ion gun formed a
monoenergetic ion beam with an energy E0 between
0.5 and 5 keV and a current density j in the range 0.5�
20 µA cm-2. The diameter of the ion beam at the target
was 4 mm.
For determination of atoms matrixes and implanted
element concentration profiles used was the Auger - elec-
tron spectroscopy (AES) method in combination with ionic
etching. The etching was carried out using Ar+ ions with
Å0 = 3 keV at an angle of ~30 relatively to surfaces.
As an object of investigation we used the face (110) of
a GaAs monocrystal. Before ion-implantation, a surface
GaAs was cleaned by the high-temperature annealing in
combination with soft laser irradiation.
3. Results
Implantation of Ba+ ions was carried out under fixed
energy (Å0 = const) ranged within 0.5 to 5 keV. In doing
so, the most important change of the state and properties
of GaAs surface layers occured at relatively low energies
of ions. So, in this work, the main results are related to
Å0= 0.5 keV.
The photoelectron spectra for a fixed photon energy
of hν = 10.8 eV for GaAs (110) implanted by barium ions
having energy Å0 = 0.5 keV with different doses shown in
Fig. 1. On the basis of analysis of photoelectron spectra,
it is possible to get information on distribution of density
of electronic states and parameters of energy bands [6].
The energy bond Åeb of electrons is axis of abscissas. For
all photoelectron energy distribution curves (PED) we
used the same scale in vertical, chosen in such manner,
that the area under each curve proportional to the value
an electron quantum yield from samples. It is seen that
all curves have a thin structure. In case of unimplanted
GaAs, formation of the thin PED structure is mainly con-
tributed by ð - orbitals of Ga and As, as well as As s-states
[7]. Observe that peak Ga with Åeb = � 1 eV and peak As
with Åeb = - 3 eV is typical only for bound states. Initial
part of the spectrum contains some subsidiary features,
evidently, connected with surface states (curve 1). Ion-
implantation depending on dose of irradiation results in
a change of the photoelectron spectrum structure. Already
at the dose D = 8⋅1014ñm�2, there arises a new feature
with the energy bond Åeb = �0.6 eV in the spectrum. In
the range D = 8⋅1014 - 6⋅1015cm�2, intensity of this feature
quickly increases with the growing dose. At that intensity
of GaAs (Åeb = �1 eV) main peak, appreciably decreases
which is caused by excitation of Ga 4ð electrons, and the
As peak with Åeb = � 3 eV noticeably widens slightly
increasing in amplitude. The analysis of the data obtained
by ultra-violet photoelectron spectroscopy (UVPS) to-
gether with the data of AES have shown that within this
range of irradiation doses the process of ion implanta-
tion is followed by disordering the surface layer, decom-
position of GaAs by components, some enriching of the
surface with unbound As atoms at the expense of their
prior diffusion to surfaces. Evidently, these As atoms at
once enter into the chemical bond with interstitial Ba
atoms, and separation of a certain quantity of atomic
gallium takes place. Therefore, appearance of new peak
in spectrum of photoelectrons is explained by formation
of Ba+As compounds, and the displacement of Fermi
level (EF) position by initiation of deep levels in the for-
bidden semiconductor gap, as a consequence of separa-
tion of atomic gallium, accompanied by formation the
different defects in the crystalline structure. (In fact, EF
position is not changed, and displaced is the top edge of
the valent band ÅV and the bottom of the conductivity
band ÅÑ, at the expense of formation of 0impurity levels
near it).
At D = (6 � 8)⋅1015 cm�2, ion-implanted layer of GaAs
still keeps the properties typical of semiconductors (the
width of the forbidden gap is ~0.8 eV). For further growth
of dose in near surface range the concentration of arsenic
decreases (through partial desorption from surfaces and
certain diffusion deep into the sample), while the near
surface range is enriched by Ba atoms, part of which can
form certain bonds with Ga atoms. Accordingly, their
contribution to formation of photoelectrons increases. All
this results in sharp changes of the structure of PED
curves: the spectrum front is displaced by ~ 1 eV to the
high energy side, and its form becomes typical for metal-
alloy emitters. These changes occur up to D = 8⋅1016 cm-
2. Further increase of the irradiation dose doesn�t result
in noticeable changes of the dependence N(E) (Fig. 1,
curve 6). In this case, ion-implanted layers are completely
disordered, and on the curve N(E) one can observe,
Fig. 1. Photoelectron spectra for ð-type GaAs (110), implanted
with Å0=0.5 keV Ba+ ions and doses D, ñm-2: 1 - 0; 2 - 2⋅1014; 3
- 8⋅1014; 4 - 6⋅1015; 5 - 2⋅1016; 6 - 8⋅1016.
N E( )
E = 0−4 −2E , e V v
re l. u n .
b
B a+ G a
B a+ A s
+B a G aA s→
hν = 10 .8 eV
B a
1
2
3
4
5
6
E r
P
(G a)
P
(A s)
140 SQO, 5(2), 2002
M.T. Normuradov et al.: Influence of ion implantation and annealing...
mainly, characteristics, intrinsic to the system [Ba+Ga]
and the clean barium, i.e. there occurs «metallization»
of near surface GaAs layers. Thickness of these layers at
Å = 0.5 keV are 25�30 Å.
Post-implantation high-temperature or laser anneal-
ing can modify the structure and properties of the surface
The dynamics of changing the PED curve for differ-
ent Ò in GaAs implanted with Å0 = 0.5 keV Âà+ ions is
shown in Fig. 3. It is seen that at Ò = 800 K peaks with
Åeb = 0.6 and �4.2 eV typical to alloys Ba - Ga of disap-
pear, and new features appear. Evidently, new peaks
appear in consequence of forming the three-component
compound of Ba - Ga � As type. Under these conditions,
semiconductor properties of near surface layer becomes
restore. The width of this system forbidden gap is 0.6 eV.
With Ò growing up to 900 K, intensity of peaks with
energy bonds of �0.7 and -5eV sharply decreases, and
intensity of peak �3.2eV increases only a little (Fig. 3,
curve 3). These changes are probably caused by decreas-
ing content of barium in the system [Ba -Ga -As] and by
growth of arsenic concentration in it. At Ò = 900 K the
compound Ga0.6Ba0.4As is formed. For this system the
width of forbidden gap is equal to ~1.0 eV, i.e. these
films are heterostructural. All features typical of GaAs,
in the photoelectron spectrum, are fixed only after long
annealing (3 hours and more) of sample at Ò = 1000 �
1100 K.
4. Conclusions
For the first time, researched is the influence of low
energy Ba+ ions implantation on the structure of pho-
toelectron spectra of GaAs surfaces. It is determined
that implantation of Ba+ ions results in the formation
of compounds of the BaAs type at doses of D = 8⋅1014 �
6⋅1015 cm-2, and intermetallic Ga+Ba compounds at doses
D ≥ 1016 cm-2.
Post implantation annealing starting with Ò = 700 �
750 K results in recrystallization of amorphous layers
of the ion-implanted materials. Such annealing promotes
the crystallization of disordered layers, formation of new
compounds, decrease of the concentration of unbound
substrate and implanted element atoms. In the Fig. 2
shown are the concentration profiles of Âà, As and Ga
versus temperature Ò, for GaAs implanted by Ba+ with
Å0 = 0.5 keV. The samples were annealed for 30 min. It is
seen that main changes in concentrations of atoms oc-
curs from Ò = 650�700 Ê. With growing Ò, barium con-
centration monotonically decreases, the curve ÑGa(Ò) at
Ò = 800 K passes across its minimum, and the curve
CAs(Ò) at Ò = 900�950 K across its maximum. The analy-
sis of the data of AES has shown that at Ò ≥ 700 Ê prac-
tically all Ba atoms forms chemical bonds with matrix
atoms. In the range Ò = 700�1000 K, mainly formed are
three-component compounds of the Ga1-õÂàõAs type,
where õ value depends on Ò. For example, at Ò = 800 K
value õ = 0.5, and at Ò = 900 K � õ = 0.4. Further in-
crease of the temperature results in decomposition of
three-component compounds and intensive evaporation
of their components from surfaces. Starting from Ò =
700K, the change of the near surface layer composition
is accompanied by recrystallization of disordered lay-
ers. In the range of Ò = 700 � 800 K, there are concentric
circles on HEED pictures, which is typical of
polycrystalline films. There are point reflexes, inherent
to singlecrystals in HEED pictures starting from 850�
900 K. The type and parameters of this system lattice are
determined. The three-component system had the cubic
lattice, which is similar to that of substrate, i.e. the epitaxy
film was formed. The parameter of this lattice was a =
5.73 ± 0.03 Å which is some longer than a for GaAs
(~5.65Å).
Fig. 2. Influence of the temperature on Âà, Ga and As atoms
surface concentration for GaAs implanted with Å0 = 0.5 keV Ba+
ions.
Fig. 3. Influence of temperature annealing on photoelectron spec-
tra of GaAs implanted with Å0 = 0.5 keV Ba+ ions under Ò, K: 1
- 300; 2 - 800; 3 - 900; 4 - 1000.
B a
B a -G a -A s
G a
EA s
F
1
2
3
4
( )
re l. u n .
N E
E ,e Vb E = 0v-4 -2
+B a G aA s→
E = 0 .5 k eV0
C
, a
t.
%
40
20
0
500 700 900 T , K
C G a
A sC
B aC
M.T. Normuradov et al.: Influence of ion implantation and annealing...
141SQO, 5(2), 2002
and redistribution of the atoms of matrixes and implanted
ions in ion-implanted layer. At Ò = 900 K, there occurs
the full crystallization of the near surface layer and for-
mation of the epitaxial Ga0.6Ba0.4As film with the thick-
ness 30�40 Å.
The determined parameters of energy bands and crys-
talline lattice in the three-component system Ga0.6Ba0.4As
are the follows: the width of forbidden gap is Eg = 1 eV,
the lattice is constant a = 5.73 Å.
References
1. H. Rissel, I. Ruge, Ion implantation. Edited by Gusevoy M.I.
Moscow, Nauka, 1983, 360 p.
2. N. Lieske, R. Nezel. Auger electron spectroscopy and elec-
tron energy loss spectroscopy studies of the formation of sili-
con nitride by implanting low energy nitrogen ione into sili-
con //Thin Solid Films 86 (1) p. 7 � 44 (1981).
3. V.G. Lifshits. Electron spectroscopy and atomic processes on
the surface of silicon. Moscow, Nauka, p. 200 (1985)
4. M.T. Normuradov, B.E. Umirzakov. Energetic spectra of the
surface of solid state, implanting of low energy ions. Tashkent.
Pub.:�Fan�. 1989. 158 p.
5. U.A. Arifov. Interaction of the atomic particles with solid
surface. Moscow, Nauka, p. 22 � 24, 242 � 243 (1968).
6. V.K. Adamchuk, S.I. Fedosenko. Investigation of the proc-
ess forming the �semiconductor � metal� contact by ultravio-
let photoelectron spectroscopy method. //Izv RAN. Ser. Phys.
43 (3), p. 523 � 528 (1979).
7. Molecular beam epitaxy and heterostructures. Edited by
Leroy L. Chang, Klaus Ploog. Martinus Nijhoff Publishers,
1985, 520 p.
8. B.E. Umirzakov, M.T. Normuradov, A.K. Tashatov, I.N.
Kodirov. Changes of electronic structure of Pd, Si, GaAs,
CaF2 surface while low energy ion implantation and the fol-
lowing annealing. //9th International Confer. on Surface Modi-
fication of Metals by Ion Beams. San Sebastian - Spain, 1995,
p. 228.
9. F.G. Djurabekova, T.S. Pugacheva, D.A.
Tashmukhamedova, B.E. Umirzakov. Barium concentration
profiles for GaAs under high dose low energy Ba+ ions bomb-
ing. //Proc. of the 13th International Conference �Ion-Sur-
faces Interactions�, Moscow, 1997, 2, p.224.
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