Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation
We used the method of nets to calculate the thermoelastic stresses on the GaAs surface caused by a non-destructive nanosecond pulse laser irradiation (λ = 0.532 µm) with diffraction spatial intensity modulation from a shield with rectangular cut. The structure of irradiated subsurface layers of s...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2007
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| Zitieren: | Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation / D.S. Moscal, L.L. Fedorenko, M.M. Yusupov, M.M. Golodenko // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 80-83. — Бібліогр.: 14 назв. — англ. |
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irk-123456789-1181292017-05-29T03:05:21Z Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation Moscal, D.S. Fedorenko, L.L. Yusupov, M.M. Golodenko, M.M. We used the method of nets to calculate the thermoelastic stresses on the GaAs surface caused by a non-destructive nanosecond pulse laser irradiation (λ = 0.532 µm) with diffraction spatial intensity modulation from a shield with rectangular cut. The structure of irradiated subsurface layers of samples was studied by the AFM method. A periodic islet structure formed in the process of diffusive redistribution of defects was revealed by the level-by-level chemical etching. 2007 Article Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation / D.S. Moscal, L.L. Fedorenko, M.M. Yusupov, M.M. Golodenko // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 80-83. — Бібліогр.: 14 назв. — англ. 1560-8034 PACS 71.10.-W http://dspace.nbuv.gov.ua/handle/123456789/118129 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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We used the method of nets to calculate the thermoelastic stresses on the GaAs
surface caused by a non-destructive nanosecond pulse laser irradiation (λ = 0.532 µm)
with diffraction spatial intensity modulation from a shield with rectangular cut. The
structure of irradiated subsurface layers of samples was studied by the AFM method. A
periodic islet structure formed in the process of diffusive redistribution of defects was
revealed by the level-by-level chemical etching. |
| format |
Article |
| author |
Moscal, D.S. Fedorenko, L.L. Yusupov, M.M. Golodenko, M.M. |
| spellingShingle |
Moscal, D.S. Fedorenko, L.L. Yusupov, M.M. Golodenko, M.M. Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Moscal, D.S. Fedorenko, L.L. Yusupov, M.M. Golodenko, M.M. |
| author_sort |
Moscal, D.S. |
| title |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation |
| title_short |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation |
| title_full |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation |
| title_fullStr |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation |
| title_full_unstemmed |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation |
| title_sort |
periodic subsurface structures in gaas formed by spatially modulated nanosecond pulse laser irradiation |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2007 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118129 |
| citation_txt |
Periodic subsurface structures in GaAs formed by spatially modulated nanosecond pulse laser irradiation / D.S. Moscal, L.L. Fedorenko, M.M. Yusupov, M.M. Golodenko // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 80-83. — Бібліогр.: 14 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT moscalds periodicsubsurfacestructuresingaasformedbyspatiallymodulatednanosecondpulselaserirradiation AT fedorenkoll periodicsubsurfacestructuresingaasformedbyspatiallymodulatednanosecondpulselaserirradiation AT yusupovmm periodicsubsurfacestructuresingaasformedbyspatiallymodulatednanosecondpulselaserirradiation AT golodenkomm periodicsubsurfacestructuresingaasformedbyspatiallymodulatednanosecondpulselaserirradiation |
| first_indexed |
2025-07-08T13:24:39Z |
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2025-07-08T13:24:39Z |
| _version_ |
1837085312858193920 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 80-83.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
80
PACS 71.10.-W
Periodic subsurface structures in GaAs formed
by spatially modulated nanosecond pulse laser irradiation
D.S. Moscal1, L.L. Fedorenko2, M.M. Yusupov2, M.M. Golodenko3
1 Slovyansk State Pedagogical University, 19, General Batyuk str., 84116 Slovyansk, Ukraine
Phone: +380 (06266) 5-06-84; fax: +380 (06262) 9-19-50; e-mail: dsmosk@mail.ru
2 V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
45, prospect Nauky, 03028 Kyiv, Ukraine
Phone: +380 (44) 525-64-77; fax: +380 (44) 525-43-82; e-mail: lfedor@isp.kiev.ua, ny@isp.kiev.ua
3 Donbas National Academy of Civil Engineering and Architecture
2, Derzhavin str., Makiivka, 86123 Donbas region, Ukraine
Phone: +380 (0622) 90-29-38, +380 (0623) 22-24-67
Fax: (06232) 4-46-82; e-mail: mailbox@dgasa.dn.ua
Abstract. We used the method of nets to calculate the thermoelastic stresses on the GaAs
surface caused by a non-destructive nanosecond pulse laser irradiation (λ = 0.532 µm)
with diffraction spatial intensity modulation from a shield with rectangular cut. The
structure of irradiated subsurface layers of samples was studied by the AFM method. A
periodic islet structure formed in the process of diffusive redistribution of defects was
revealed by the level-by-level chemical etching.
Keywords: laser, diffraction, intensity modulation, GaAs, thermoelastic stress,
subsurface layer, point defect, islet structure.
Manuscript received 07.06.07; accepted for publication 27.09.07; published online 30.11.07.
1. Introduction
Laser technologies of creation of semiconductor
structures allow one to set the required energy
distribution on irradiated surfaces. It was succeeded to
form nanostructures with specific properties on the
GaAs surface by different methods of laser radiation
intensity modulation [1–5]. For a modification of the
thin subsurface layer of a semiconductor, it is necessary
to use the fundamental absorption of short laser radiation
pulses with a certain energy distribution on the irradiated
surface [5, 6]. The present paper deals with researching
the structural changes in subsurface GaAs layers caused
by diffraction-modulated laser nanosecond pulses with
the quantum energy exceeding the semiconductor band
gap. The holographic energy distribution creates locally
warmed-up regions on the irradiated crystal surface. This
results in the origination of thermoelastic stresses in the
sample subsurface layer, which stimulates the generation
and the diffusive redistribution of point defects [7].
2. Experiment
We studied the influence of the pulse laser radiation
passed through a diffraction mask on the semiconductor
surface (Fig. 1). A chemically polished surface (100) of
GaAs brand AGChT-1-25а-1 was irradiated. A
rectangular mask was set at a distance of 10 µm above
the irradiated surface. The laser radiation wavelength
corresponded to the resonance light absorption by the
semiconductor surface. The irradiation energy density on
the diffraction mask was 160 mJ/cm2. A short-term
metallographic etching in AB solution was used [8] to
investigate the structural changes appeared in the subsur-
face layer at a depth of ∼1 µm. The chemically treated
surface was explored by atom force microscope. A
periodic islet structure was exposed as a result (Fig. 2).
3. Results and discussion
A computer modeling of thermal fields arising in the
GaAs subsurface layer under exposure of the absorbed
diffraction-modulated laser radiation was performed to
clarify the processes of formation of subsurface struc-
tures. We have solved the heat conduction equation [9]
g
z
T
zt
T
c +
∂
∂
κ
∂
∂
=
∂
∂
ρ , where c is the specific heat
capacity, ρ is the matter density, T is the temperature, t
is the time, z is the co-ordinate in the direction normal to
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 80-83.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
81
Fig. 1. Scheme of the irradiation of a sample through a dif-
fraction mask with rectangular cut.
Fig. 2. AFМ-image of the GaAs subsurface structure formed
after the laser irradiation through a diffraction mask with a
subsequent short-term chemical etching.
the surface, κ is the heat conductivity, and g is the
thermal power released per unit volume. To consider the
dynamic processes and changes of the physical
properties of the semiconductor during the influence of a
laser radiation pulse, the analytical expressions for
temperature dependences of parameters (Fig. 3) were
used and the heat conduction equation has been solved
by the method of nets by the implicit calculation scheme.
The diffraction modulation of laser radiation was
characterized by the coefficient of intensity distribution
γ . When a laser beam passes through a rectangular cut
diffraction mask, the coefficient γ is calculated by the
formula [10]
∏ ∏
= =
ϑη++
ϑξ+==γ
2
1
2
1
22
0
1 )(
2
1
)(
2
1
4
1
i i
iiI
I ,
where iI is the intensity produced by diffraction on one
of the cut sides; and the parameters )( iϑξ and )( iϑη
are determined in terms of Fresnel integrals.
Computations were conducted in accordance with the
terms of the experiment. A periodic distribution of light
energy density was determined as a result. Its period on
the surface of semiconductor is stabilized at a distance
∼ 24 µm along the bisector of the diffraction mask
rectangular cut (Fig. 4).
a
b
c
d
Fig. 3. Temperature dependences: a) light absorption for a
wavelength of 0.54 µm, b) thermal expansion, c) heat
conductivity, d) heat capacity.
16.0
10.2
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 80-83.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
82
Fig. 4. Falling energy density depending on the distance along
the bisector of a diffraction mask with rectangular cut.
While calculating, we have considered also the
absorption of the laser light in GaAs vapors. If we take
into account only the single ionization of atoms in
vapors, then the absorption coefficients of radiation in
the vapors for each of the component at the unit of
distance can be written down in the form [11]
−
−=
V3
3
3
0
34
V3V3
6
3 exp
433 kT
hA
ch
nkTe ν
πεν
χ and
−
−=
V5
5
3
0
34
V5V5
6
5 exp
433 kT
hA
ch
nkTe ν
πεν
χ ,
where e is the elementary charge, k is the Boltzmann
constant, h is the Planck constant, c is the light velocity
in vacuum, ε0 is the electric constant, ν is the laser
optical radiation frequency, A is the energy of ionization
of an atom, 3Vn and 5Vn are atom concentrations in the
semiconductor vapors at the moment of their
sublimation from the surface, and V3T and V5T are the
temperatures of vapors of elements 3A and 5B ,
respectively.
Fig. 5. Distribution of the thermoelastic stress gradient along
the bisector of a diffraction mask with rectangular cut.
Fig. 6. AFM-profile of GaAs surfaces at a distance of ∼24 µm
from a diffraction mask with rectangular cut.
Only a thin subsurface layer (thickness δ ~ α–1)
confined on the surface by a laser spot with the diameter
∅ ≥ 100 µm that lies on the massive bedding is heated
under the action of pulse laser irradiation. Therefore, we
have considered the one-dimensional case. Taking the
temperature dependence of the linear thermal expansion
coefficient into account, it is possible to calculate a
relative deformation of compression [12] ∫α=ε
T
T
dTT
0
)( ,
where )(Tα is the linear thermal expansion coefficient
as a function of temperature. The maximum mechanical
stress arises in directions [010] and [001] under the
irradiation of crystal plane (100). The tension tensor
components are calculated as follows [13]:
ε+=σ=σ )( 12113322 cc , where 11c and 12c are the
elasticity tensor components. The distribution of
thermoelastic stress gradient is given by the spatial
modulation of the irradiation intensity since the periods
of the diagrams represented in Figs. 4 and 5 coincide.
The heterogeneous stress distribution on the sample
surface results in the generation and the diffusive
alteration of point defects in the semiconductor [11]. A
subsurface structure appears as a result. The arrangement
of the experimentally exposed structures coincides with
the distribution of thermoelastic stress gradient that is
confirmed by the AFM-profiles presented in Fig. 6.
Consequently, the subsurface islet structures appear as a
result of the absorption of radiation with diffraction
modulated intensity by the semiconductor.
4. Conclusions
Under exposure of the nanosecond laser pulse radiation
with spatially modulated power density, a periodic islet
structure appears in the subsurface layer. The structure
period is determined by the diffraction intensity
distribution on the irradiated surface. In contrast to other
applications of interference effects [14], we used the
laser radiation with under-threshold energy density. The
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 80-83.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
83
obtained results can be used for the development of laser
technologies for the fabrication of microelectronic
devices.
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