Structure and physical characteristics of ohmic contacts based on Fe and Ge films
Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт- амперные харак...
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| Date: | 2014 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2014
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| Cite this: | Structure and physical characteristics of ohmic contacts based on Fe and Ge films / О.V. Vlasenko, L.V. Odnodvorets, I.Yu. Protsenko // Вопросы атомной науки и техники. — 2014. — № 4. — С. 130-133. — Бібліогр.: 10 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859711489248591872 |
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| author | Vlasenko, О.V. Odnodvorets, L.V. Protsenko, I.Yu. |
| author_facet | Vlasenko, О.V. Odnodvorets, L.V. Protsenko, I.Yu. |
| citation_txt | Structure and physical characteristics of ohmic contacts based on Fe and Ge films / О.V. Vlasenko, L.V. Odnodvorets, I.Yu. Protsenko // Вопросы атомной науки и техники. — 2014. — № 4. — С. 130-133. — Бібліогр.: 10 назв. — англ. |
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| description | Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт- амперные характеристики и следующие рабочие параметры: сопротивление на квадрат площади 0,3 Ом/м² и термический коэффициент сопротивления 6∙10⁻⁴ К⁻¹.
.
Запропоновано застосування методу пошарової конденсації з наступним відпалюванням від 300 до 900 К
для формування омічних контактів на основі плівок Fe і Ge. Проведенo дослідження мікроструктури і
фазового складу контактних систем Fe/Ge, для яких отримано симетричні лінійні вольт-амперні
характеристики та наступні робочі параметри: опір на квадрат площі 0,3 Ом/м²
і термічний коефіцієнт опору
6∙10⁻⁴ К⁻¹.
Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт- амперные характеристики и следующие рабочие параметры: сопротивление на квадрат площади 0,3 Ом/м² и термический коэффициент сопротивления 6∙10⁻⁴ К⁻¹.
|
| first_indexed | 2025-12-01T05:02:54Z |
| format | Article |
| fulltext |
130 ISSN 1562-6016. ВАНТ. 2014. №4(92)
STRUCTURE AND PHYSICAL CHARACTERISTICS OF OHMIC
CONTACTS BASED ON Fe AND Ge FILMS
О.V. Vlasenko, L.V. Odnodvorets, I.Yu. Protsenko
Sumy State University, Applied Physics Department, Sumy, Ukraine
E-mail: protsenko@aph.sumdu.edu.ua
In the the article the application of the method layered condensation followed by annealing from 300 to 900 K
for formation of ohmic contacts based on the Fe and Ge films was proposed. The investigations of microstructure
and phase composition of the contact systems Fe/Ge, which received symmetric linear current-voltage
characteristics and the following operating parameters: resistance on the square area 0.3 /m
2
, thermal coefficient
of resistance 6∙10
-4
К
-1
and symmetric linear current-voltage characteristics.
PACS: 68.37.-d, 13.40.-f
INTRODUCTION
In using nonrectifying ohmic contacts, the quality of
which depend heavily on the parameters and
characteristics of microelectronic devices, their
reliability and lifetime, there is electrical connection of
the semiconductor with metal elements and conductors.
As is known [1], contact metal/semiconductor
(Me/Sem) can be either a rectifying (barrier) if potential
barrier between the metal and semiconductor tunnel-
opaque, or ohmic if the potential barrier is absent or is
tunnel-transparent to electrons. Recently, has been
considered a mechanism, when the presence of a
potential barrier metal-semiconductor space charge
layer shorted metal shunts, which are formed, for
example, by deposition of metal atoms on dislocations
and other defects in the semiconductor.
The main parameter ohmic contact, which consists
of sequentially connected resistances: in the contact area
of semiconductor and related to the passage of potential
barrier electrons, is resistance to the square area. The
authors [1] have shown, that the alloy ohmic contacts
metal-semiconductor, when the heat annealing is
dissolving semiconductor in the metal and
recrystallization, may show the mechanism of current
flow in the metal shunt, which represent a metal atoms,
that are deposited on the line defects, for example,
dislocation, and shunts the space charge layer. In this
case, the edges of these lines is concentrated electric
field and the current flowing by field emission. The
presence of metal shunts in semiconductor devices
observed in the study resistance epitaxial Ti/N films [2]
and research mechanism of reverse current flow in
diode structures in diode structures Ni/GaN [3]. The
authors [4] the study by transmission electron
microscopy of processes at interfaces ohmic contacts
Ti/Al/Mo/Au to heterogenous structures Al/GaN, it was
found, the amount of islands TiN – shunt diffusion
channels was proportional of the concentrastion of
dislocations.
The method of formation a contact based on Ge and
Cu films in work [5] is as follows. On the surface of the
plate n-GaAs (100) is formed by the mask. Then, by
electron-beam evaporation is performed under vacuum
layer deposition of Ge and Cu films of total thickness
0.2 mm and a film thickness of Ge, defining the weight
content of Ge metallization equal to 40%. Thereafter,
the plate is subjected to a first heat treatment of GaAs in
a single vacuum cycle at T1 = 100 °C for t = 60 min.
The plate is removed from the vacuum chamber, and
after removal of the mask is exposed to a second heat
treatment at a temperature of T2 = 400 °C for t = 30 min
in vacuum. Implementation of the first annealing in a
single vacuum cycle allows formation of a contact start
conditions in which the surface of the deposited films is
not more oxidized. The disadvantages of this method
may include insufficiently low value of reduced contact
resistance.
The surface morphology of the contacts and reflect
the heterogeneity of physical and chemical processes
that occur in the volume of contacts and the interface
film/substrate. With increasing temperature in the
contact system based on Au and Ge films on GaAs
substrate at a temperature above 300 °C, the processes
of formation of intermetallic compounds such as AuGa
and AuGe, as described in detail in [6, 7].
Authors [8] showed that the nature of the processes of
phase formation in contacts Au/Ge/Ni/GaAs during
thermal cycling obtaining ohmic contacts determines
their electrical parameters. After heating and holding at
the maximum temperature and the physical and
chemical processes proceed at the cooling.
In work [9] was investigated the ohmic properties of
film systems Au/(Pd,Pt)/Zn/Pd/p-InP, focusing on the
role of the Pd or Pt in Au-free metallization. Both the
lowest contact resistivity of 7∙10
−2
∙m
-2
and a flat
diffusion front were obtained for a sample with a
Au/Pt/Zn/Pd/p-InP contact material after annealing,
indicating that the Pt layer was more effective than the
Pd layer in preventing Zn external diffusion during the
annealing process.
The purpose of this work was to research the
microstructure, phase composition, thermoresistive
properties and current-voltage characteristics of ohmic
contacts based on films of Fe and Ge, the layer formed
by condensation followed by annealing from 300 to
900 K.
EXPERIMENTAL TECHNIQUES
To obtain on double-layer film samples Fe/Ge/S (S –
substrate) the vacuum chamber type VUP-5M was used.
Layer to layer condensation and annealing of films
carried thermoresistive method at the temperature of
glass-ceramic substrate Тs 300 К and annealing on
mailto:protsenko@aph.sumdu.edu.ua
ISSN 1562-6016. ВАНТ. 2014. №4(92) 131
the interval 300…900 K during three cycles of thermal
stabilization «heating↔cooling».
Measurement of electrical resistance was carried out
in automatic mode using the software and hardware
complex (Fig. 1). Control the process of annealing out
software style MDI interface, developed using the
graphical programming LabVIEW was done. On the tab
of the main application window are controls (see
Fig. 1,b), that define the parameters of annealing, blocks
read information, of work hardware and software
elements and output information. Measurement of
electrical resistance was carried out by four-circuit. On
the program the buttons: «START» the beginning of
the program, «STOP» end of exit from the program,
«SAVE» store data on annealing to the hard disk as a
text table «AUTO» enable or disable the automatic
annealing, and switch «heating/cooling», which allows
you to change the direction of the move process at any
point in the program. To measure the resistance of each
sample was designed separate measuring circuit based
on constant high accuracy resistors. Output data
elements include windows plotting (see Fig. 1,c) to
visualize the temperature dependence of resistance Ri(T)
and temperature change with time T(t), and the data
read off the table, the current temperature, rate of
change, the current resistance patterns. Upgrade graphs
and tables occurs after each new reading, current
indicators are updated with the maximum possible
frequency that depends on the hardware capabilities of
the system.
Thermal coefficient of resistance (TCR) was
calculated on the basis of the third annealing cycle by
the ratio:
T
R
R
0
1
,
where R0 – initial resistance of the sample; ΔТ –
temperature interval.
Crystal structure and phase composition of the films
by electron microscopy and electron diffraction methods
(microscope TEM-125К) was investigated. Structural
and electrical schemes for current-voltage
characteristics of the contact, diffraction pattern and
temperature dependence of TCR for double-layer films
Fe/Ge/S shown on the Fig. 2.
THE EXPERIMENTAL RESULTS
The study of the structure and phase composition of
double-layer films based on Fe and Ge with a total
concentration of atoms of individual components –
70 at.% (for example, Fe(30)/Ge(25)/S) indicates that
the ohmic contact in the form of films in the annealed
condition (see Fig. 2,с) have a crystalline structure (bcc-
Fe + fcc-FeGe + traces GeO2).
The main requirements for ohmic contacts these [1]:
under forward bias they must ensure injection of
majority carriers in the semiconductor; the reverse bias -
hinder injection of minority carriers in semiconductor;
have a minimum electrical resistance and linear current-
voltage characteristic. These conditions are satisfied
given the right pair of Me/Sem. For pair Ме/n-Sem the
electron work function of the metal (АМе) less than the
work function of electrons from the semiconductor
(АSem). In a pair of the energy of electrons in metals are
more, than the semiconductor, and in establishing
thermodynamic equilibrium of the electrons from the
metal flows into the semiconductor.
a
b
с
Fig. 1. Block diagram of the automated system for
determining the TCR of film materials (a), appearance
of the main application window to automatically sample
annealing (b) and program window for constructing
of the temperature dependence (c)
Fermi level WF the metal and semiconductor are
aligned. Contact the electric field Ек directed from metal
to semiconductor, which results in bending of the
energy levels of the minority carriers. If due to the
choice of material value works out electrons from the
metal and semiconductor differ insignificantly
АМе АSem (АFe 4.31 eV; АGe 4.40 еV), barrier
height will be minimal.
132 ISSN 1562-6016. ВАНТ. 2014. №4(92)
а b
c
d
Fig. 2. Structural (a) and electrical (b) schemes for current-voltage characteristics, diffraction pattern (c)
and temperature dependence of TCR (d) of double-layer films Fe/Ge/S
U
in
,V-60 -40 -20 20 40 60
I
out
,mА
-3
-2
-1
1
2
3
a
:,Iin A ●,○ – 0.1; ■, □ – 0.3; ♦, ◊ – 0.5
U
in
,V-60 -40 -20 20 40 60
I
out
,mА
-1
1
▲, Δ – 0.8
b
Fig. 3. The current-voltage characteristics
for annealed to 900 К films Fe(30)/Ge(25)/S.
The area of transition Ме/Sem: S = a
.
(b+d):
10
-5
(a) and 2.5
.
10
-6
m
2
(b)
On the Fig. 3 shows the experimental current-
voltage characteristics for annealed to 900 К films
Fe(30)/Ge(25)/S at the different area of transition
Ме/Sem.
In the case system Fe/Ge/S with atomic radius of the
metal rFe = 0.126 nm and the lattice parameter of
semiconductor aGe = 0.566 nm the resistance ohmic
contact is calculated as follows:
,
)(
2 pr
WT
Rc
where ρ 10
-7
∙m – resistivity of the metal;
β 6∙10
-4
К
-1
; W 1 nm – width of the space charge
layer; р 2,1∙10
10
m
-2
[10] – dislocation density in the
film Ge, which can be adsorbed atoms Fe.
For a system Fe/Ge/S value of contact resistance
Rc = 0.38
/m
2
, which will not affect the contact values
of parameters of electronic devices.
The films Fe/Ge/S in this case are relatively high
resistivity (ρ (0.5…2.0)∙10
-6
∙m) and low TCR
(β (5.8…6.2)∙10
-4
К
-1
), that meets the requirements to
the ohmic contacts.
This work performed within the state of scientific
themes with the financial support of the Ministry
Education and Science of Ukraine (20122014).
REFERENCES
1. T.V. Blank, Yu.A. Hol’bert // Semiconductors.
2007, v. 41, p. 1281.
2. J. Narayan, P. Tiwari, X. Chen, J. Singh,
R. Chowdhary, T. Zheleva // Appl. Phys. Lett. 1992,
v. 61, p. 1290.
3. E.J. Miller, D.M. Schaadt, E.T. Yu, X.L. Sun,
L.J. Brillson, P. Waltereit, J.S. Speck // J. Appl. Phys.
2003, v. 94, p. 761.
ISSN 1562-6016. ВАНТ. 2014. №4(92) 133
4. Chin-Yuan Hsu // Jap. J. Appl. Phys. 2005, v. 44,
p. 7424.
5. M.O. Aboelfotoh, S. Oktyabrsky, J. Narayan // J.
Mater. Res. 1997, v. 12, N 9, p. 2325.
6. V.I. Strikha, E.V. Buzaneva // Radio i svjaz’.
1987, 256 p. (in Russian).
7. T.A. Bryanceva, A.I. Volkov, A.B. Ormont //
Electron Technic. 1976, N 2 (100), p. 65 (in Russian).
8. V.M. Filimonov, V.I. Yurchenko // Sbornik
trudov VI Vsesoyuznogo soveschaniya po issledovaniyu
arsenida galliya, Tomsk, 1987, v. 2, p. 48 (in Russian).
9. S. Hwang, J. Shim, Y. Eo // J. Korean Phys. Soc.
2005, v. 46, N 4, р. 751.
10. S.B. Samavedam, T.A. Langdo, C.W. Leitz //
Appl. Phys. Lett. 1998, v. 72, p. 1718.
Статья поступила в редакцию 24.01.2014 г.
СТРУКТУРА И ФИЗИЧЕСКИЕ ХАРАКТЕРИСТИКИ ОМИЧЕСКИХ КОНТАКТОВ
НА ОСНОВЕ ПЛЕНОК Fe И Ge
А.В. Власенко, Л.В. Однодворец, И.Е. Проценко
Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для
формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и
фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт-
амперные характеристики и следующие рабочие параметры: сопротивление на квадрат площади 0,3 Ом/м
2
и термический коэффициент сопротивления 6∙10
-4
К
-1
.
СТРУКТУРА І ФІЗИЧНІ ХАРАКТЕРИСТИКИ ОМІЧНИХ КОНТАКТІВ НА ОСНОВІ
ПЛІВОК Fe І Ge
О.В. Власенко, Л.В. Однодворець, І.Ю. Проценко
Запропоновано застосування методу пошарової конденсації з наступним відпалюванням від 300 до 900 К
для формування омічних контактів на основі плівок Fe і Ge. Проведенo дослідження мікроструктури і
фазового складу контактних систем Fe/Ge, для яких отримано симетричні лінійні вольт-амперні
характеристики та наступні робочі параметри: опір на квадрат площі 0,3 Ом/м
2
і термічний коефіцієнт опору
6∙10
-4
К
-1
.
|
| id | nasplib_isofts_kiev_ua-123456789-80344 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-01T05:02:54Z |
| publishDate | 2014 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Vlasenko, О.V. Odnodvorets, L.V. Protsenko, I.Yu. 2015-04-16T10:28:42Z 2015-04-16T10:28:42Z 2014 Structure and physical characteristics of ohmic contacts based on Fe and Ge films / О.V. Vlasenko, L.V. Odnodvorets, I.Yu. Protsenko // Вопросы атомной науки и техники. — 2014. — № 4. — С. 130-133. — Бібліогр.: 10 назв. — англ. 1562-6016 PACS: 68.37.-d, 13.40.-f https://nasplib.isofts.kiev.ua/handle/123456789/80344 Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт- амперные характеристики и следующие рабочие параметры: сопротивление на квадрат площади 0,3 Ом/м² и термический коэффициент сопротивления 6∙10⁻⁴ К⁻¹. . Запропоновано застосування методу пошарової конденсації з наступним відпалюванням від 300 до 900 К для формування омічних контактів на основі плівок Fe і Ge. Проведенo дослідження мікроструктури і фазового складу контактних систем Fe/Ge, для яких отримано симетричні лінійні вольт-амперні характеристики та наступні робочі параметри: опір на квадрат площі 0,3 Ом/м² і термічний коефіцієнт опору 6∙10⁻⁴ К⁻¹. Предложено применение метода послойной конденсации с последующим отжигом от 300 до 900 К для формирования омических контактов на основе пленок Fe и Ge. Проведены исследования микроструктуры и фазового состава контактных систем Fe/Ge, для которых получены симметричные линейные вольт- амперные характеристики и следующие рабочие параметры: сопротивление на квадрат площади 0,3 Ом/м² и термический коэффициент сопротивления 6∙10⁻⁴ К⁻¹. This work performed within the state of scientific themes with the financial support of the Ministry Education and Science of Ukraine (2012-2014). en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Физика радиационных и ионно-плазменных технологий Structure and physical characteristics of ohmic contacts based on Fe and Ge films Структура и физические характеристики омических контактов на основе пленок Fe и Ge Структура і фізичні характеристики омічних контактів на основі плівок Fe і Ge Article published earlier |
| spellingShingle | Structure and physical characteristics of ohmic contacts based on Fe and Ge films Vlasenko, О.V. Odnodvorets, L.V. Protsenko, I.Yu. Физика радиационных и ионно-плазменных технологий |
| title | Structure and physical characteristics of ohmic contacts based on Fe and Ge films |
| title_alt | Структура и физические характеристики омических контактов на основе пленок Fe и Ge Структура і фізичні характеристики омічних контактів на основі плівок Fe і Ge |
| title_full | Structure and physical characteristics of ohmic contacts based on Fe and Ge films |
| title_fullStr | Structure and physical characteristics of ohmic contacts based on Fe and Ge films |
| title_full_unstemmed | Structure and physical characteristics of ohmic contacts based on Fe and Ge films |
| title_short | Structure and physical characteristics of ohmic contacts based on Fe and Ge films |
| title_sort | structure and physical characteristics of ohmic contacts based on fe and ge films |
| topic | Физика радиационных и ионно-плазменных технологий |
| topic_facet | Физика радиационных и ионно-плазменных технологий |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/80344 |
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