Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures
We consider ohmic contacts to the n-InSb epitaxial layers grown on a semi-insulating GaAs substrate. The ohmic contacts are formed through titanium metallization with subsequent gilding. Using the structural (AFM and XRD) and analytical (AES) techniques, we showed that thermal annealings at Т = 300...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2006
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures / N.S. Boltovets, R.V. Konakova, Ya.Ya. Kudryk, V.V. Milenin, V.F. Mitin, E.V. Mitin, O.S. Lytvyn, L.M. Kapitanchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 58-60. — Бібліогр.: 2 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1214342025-02-10T00:35:03Z Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures Boltovets, N.S. Konakova, R.V. Kudryk, Ya.Ya. Milenin, V.V. Mitin, V.F. Mitin, E.V. Lytvyn, O.S. Kapitanchuk, L.M. We consider ohmic contacts to the n-InSb epitaxial layers grown on a semi-insulating GaAs substrate. The ohmic contacts are formed through titanium metallization with subsequent gilding. Using the structural (AFM and XRD) and analytical (AES) techniques, we showed that thermal annealings at Т = 300 °С (for 60 s) and 360 °С (for 30 s) do not change the phase composition of the metallization. This ensures thermal stability of the contacts and Hall sensors made on the basis of Au–Ti–n-InSb–GaAs(i) structures. 2006 Article Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures / N.S. Boltovets, R.V. Konakova, Ya.Ya. Kudryk, V.V. Milenin, V.F. Mitin, E.V. Mitin, O.S. Lytvyn, L.M. Kapitanchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 58-60. — Бібліогр.: 2 назв. — англ. 1560-8034 PACS 81.05.Rm https://nasplib.isofts.kiev.ua/handle/123456789/121434 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
| description |
We consider ohmic contacts to the n-InSb epitaxial layers grown on a semi-insulating GaAs substrate. The ohmic contacts are formed through titanium metallization with subsequent gilding. Using the structural (AFM and XRD) and analytical (AES) techniques, we showed that thermal annealings at Т = 300 °С (for 60 s) and 360 °С (for 30 s) do not change the phase composition of the metallization. This ensures thermal stability of the contacts and Hall sensors made on the basis of Au–Ti–n-InSb–GaAs(i) structures. |
| format |
Article |
| author |
Boltovets, N.S. Konakova, R.V. Kudryk, Ya.Ya. Milenin, V.V. Mitin, V.F. Mitin, E.V. Lytvyn, O.S. Kapitanchuk, L.M. |
| spellingShingle |
Boltovets, N.S. Konakova, R.V. Kudryk, Ya.Ya. Milenin, V.V. Mitin, V.F. Mitin, E.V. Lytvyn, O.S. Kapitanchuk, L.M. Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Boltovets, N.S. Konakova, R.V. Kudryk, Ya.Ya. Milenin, V.V. Mitin, V.F. Mitin, E.V. Lytvyn, O.S. Kapitanchuk, L.M. |
| author_sort |
Boltovets, N.S. |
| title |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures |
| title_short |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures |
| title_full |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures |
| title_fullStr |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures |
| title_full_unstemmed |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures |
| title_sort |
ohmic contacts to hall sensors based on n-insb-gaas(i) heterostructures |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2006 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/121434 |
| citation_txt |
Ohmic contacts to Hall sensors based on n-InSb-GaAs(i) heterostructures / N.S. Boltovets, R.V. Konakova, Ya.Ya. Kudryk, V.V. Milenin, V.F. Mitin, E.V. Mitin, O.S. Lytvyn, L.M. Kapitanchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 58-60. — Бібліогр.: 2 назв. — англ. |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 58-60.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
58
PACS 81.05.Rm
Ohmic contacts to Hall sensors based
on n-InSb–GaAs(i) heterostructures
N.S. Boltovets1, R.V. Konakova2, Ya.Ya. Kudryk2, V.V. Milenin2,
V.F. Mitin2, E.V. Mitin2, O.S. Lytvyn2, L.M. Kapitanchuk3
1State Enterprise Research Institute “Orion”, Kyiv, Ukraine
2V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine
3E.O. Paton Institute of Electric Welding, NAS of Ukraine, Kyiv, Ukraine
Abstract. We consider ohmic contacts to the n-InSb epitaxial layers grown on a semi-
insulating GaAs substrate. The ohmic contacts are formed through titanium metallization
with subsequent gilding. Using the structural (AFM and XRD) and analytical (AES)
techniques, we showed that thermal annealings at Т = 300 °С (for 60 s) and 360 °С (for
30 s) do not change the phase composition of the metallization. This ensures thermal
stability of the contacts and Hall sensors made on the basis of Au–Ti–n-InSb–GaAs(i)
structures.
Keywords: n-InSb–GaAs(i) heterostructure, Au–Ti metallization, Hall sensors.
Manuscript received 18.02.06; accepted for publication 29.03.06.
1. Introduction
When developing and producing various semiconductor
sensors, severe requirements are imposed not only on the
quality of starting semiconductor material, but on the
structure and electrophysical properties of ohmic contacts
as well [1, 2]. This is particularly true when a narrow-gap
semiconductor is used, either alone or as a component of
heterostructure, for production of Hall-effect magnetic
field sensors. Here we shall consider formation of ohmic
contacts to the n-InSb–GaAs(i) heterostructure.
2. Samples and experimental procedures
The Hall sensors were made on the basis of n-InSb–
GaAs(i) heterostructure. The concentration of
noncompensated donors in InSb was (3…6)×1017 cm-3;
the thicknesses of the n-InSb layer and semi-insulating
GaAs substrate were ~2 and ~350 μm, respectively;
resistivity of semi-insulating GaAs was ~107 Ohm⋅cm.
Ohmic contacts to n-InSb were formed using two-layer
titanium and gold metallization (both thicknesses of
50 nm) performed at temperatures of 300 °C (for 60 s)
and 360 °C (for 30 s).
Auger electron spectroscopy (AES) was used to
study the concentration depth profiles of contact
components before and after rapid thermal annealing
(RTA). Morphology of the metal–InSb interface was
investigated using atomic force microscopy (AFM),
while the phase composition of metallization was
studied using X-ray diffraction (XRD).
The sensitive elements of Hall sensors were
prepared using the following microelectronic procedu-
res: (i) preparation of metal films for electrical contacts
by magnetron sputtering and electrochemical deposition;
(ii) photolithography to form the topology of the
sensitive elements and metal contacts; (iii) micro-
machining to produce the sensing element; typically
1.0 mm2 square and 0.35 mm thick (see Fig. 1). We
measured temperature dependences of both sensor input
and output resistances and Hall voltage UH using chips
and contact resistivity of test structures.
3. Experimental results and discussion
Surface morphology features of the starting InSb films
and Au–Ti layers sputtered onto them and treated
thermally as well as roughness height distribution over
the sample surface have shown that surfaces of both the
starting and metallized epitaxial films are essentially
non-uniform. This is due to the nature of structure
defects produced in the InSb layers during their epitaxial
growth that are related, first of all, to misfit of InSb and
GaAs crystal lattices (see Fig. 2). Our AFM studies of
the gold film surface made before and after annealing
of the contacts showed that the long-term thermal
annealing at lower temperatures (see Fig. 3а, b and
Table) leads to bigger changes of surface relief than the
short-term one at a higher temperature (Fig. 3с).
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 58-60.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
59
0
0.4
0.8
μm
0
40
nm
μm0 50. 10.0
50.
0 0 nm
5 nm0
100 nm
Fig. 2. 3D and 2D images of surface of the starting InSb film.
0
0.4
0.8
μm
0
40
nm
0
0.4
0.8
μm
0
0.4
0.8
μm
a b c
Fig. 3. AFM images of Au films surfaces before (a), after annealing at 300 °C for 60 s (b) and 360 °C for 30 s (c).
Fig. 1. Stages of the process for Hall sensor chip fabrication.
1 – Ті-Аu1 contact system sputtering in vacuum. 2 – Layout
formation for local growth of contact pads. 3 – Local growth of
contact pads (Сu, Аu2). 4 – Removal of photoresist from the
wafer and etching the Au1 and Ті layers. 5 – Photolithography
and etching off sensor layout on ІnSb. 6 – Wafer slicing into
chips; presorting.
Table. Roughness height range Zr and simple average
roughness Ra of the surfaces of n-InSb–GaAs(i) and Au–
Ti–n-InSb–GaAs(i) structures.
Type of sample Type of treatment Zr , nm Ra , nm
n-InSb–GaAs(i) starting sample 19.84 2.25
starting sample 10.35 1.24
Au–Ti–n-InSb–
GaAs(i) RTA (300 °C, 60 s) 30.66 3.19
RTA (360 °C, 30 s) 16.71 1.81
Note. A surface area of 1×1 μm was analyzed.
It should be noted, however, that such changes of
the surface are rather insignificant and cannot affect the
phase and structural states of the system and interfaces
(this was proved by further investigations). Table
contains the characteristic roughness parameters of
front surfaces in the samples studied.
The reduced contact resistance measured for test
structures after RTA at Т = 300 °C (for 60 s) and 360 °C
(for 30 s) did not exceed 10-5 Ohm⋅cm. This is indicative
of a rather stable near-contact region, where an ohmic
contact is formed. The AES studies of concentration
depth profiles inherent to contact components in the test
structures (Fig. 4) showed that both the starting samples
and those after RTA retain their layered metallization
structure; noticeable mass transfer at the interfaces of
metal-metal (Au–Ti) and metal-semiconductor (Ti–
InSb) was not revealed.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 58-60.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
60
0 5 10 15 20 25
0
20
40
60
80
100
Non-annealed sample
C
on
ce
nt
ra
tio
n,
a
t %
C
O
Au
Ti
In
Sb
0 5 10 15 20 25
0
20
40
60
80
100
After thermal annealing at 300 °C for 60 s
C
on
ce
nt
ra
tio
n,
a
t %
C
O
Au
Ti
In
Sb
0 5 1 0 15 20 2 5
0
2 0
4 0
6 0
8 0
1 0 0
A fte r th e rm a l a nn e a ling a t 3 6 0 °C fo r 3 0 s
C
on
ce
nt
ra
tio
n,
a
t %
S pu tte ring tim e , m in
C
O
A u
T i
In
S b
Fig. 4. Concentration depth profiles for the Au–Ti–InSb–
GaAs(i) contact components.
The above results are confirmed also by the XRD
data. They show that, in all the metallized structures
studied, the preferred gold crystallite orientation is 〈111〉.
Probably, the titanium film involves two phases: a
principal quasi-amorphous phase (see a broad peak of
low intensity at the 20° to 25° angles in Fig. 5) and a
small amount of hexagonal polycrystalline titanium
(without preferred crystallite orientation). The above
phase composition of the Au–Ti–InSb–GaAs system
does not change in the course of thermal annealing
(Fig. 5, curves 2 and 3).
2θ, degree
Fig. 5. XRD pattern of the Au–Ti–InSb–GaAs contact before
(1) and after annealing at 300 °C for 60 s (2) and 360 °C for
30 s (3).
-100 -50 0 50 100 150
0
10
20
30
40
R
, O
hm
s
t, °C
1
2
Fig. 6. Temperature dependence of input (1) and output (2)
resistances of InSb-GaAs (i) Hall-effect magnetic field sensors.
0 50 100 150 200 250
0
10
20
30
U
x, m
V
t, °C
Fig. 7. Temperature dependences of the Hall voltage, UH, for
InSb–GаАs(і) magnetic field sensors at direct current 10 mA
and magnetic field 0.3 T.
Thus both structure and morphological properties of the
Au–Ti–n-InSb–GaAs(i) contact structures evidence that
these structures possess high thermal stability and may
serve as a basis for production of Hall sensor elements
capable to operate in a wide temperature range. Snown
in Figs 6 and 7 the main characteristics of Hall sensors
we made.
4. Conclusion
Thus, our studies demonstrated that it is possible to
produce the n-InSb–GaAs(i) Hall sensor elements with
Au–Ti contact metallization that can operate within the
temperature range from –100 °C up to +150 °C.
References
1. Handbook of modern sensors. Physics. Designs
and applications. Springer-Verlag Inc., New-York,
2004.
2. E.I. Bolvanovich, Semiconductor films and minia-
ture measuring converters. Nauka i Tekhnika,
Minsk, 1981 (in Russian).
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