Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes
In this paper, a review of microwave avalanche transit-time diode (IMPATT diode) structures has been presented. The structure of an IMPATT diode with a sharp p-n junction on Si has been considered, and the functions of the ohmic contacts have been shown. Physical and technical requirements for conta...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
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| Zitieren: | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes / Ya.Ya. Kudryk, V.S. Slipokurov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2019. — Т. 22, № 2. — С. 193-200. — Бібліогр.: 39 назв. — англ. |
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| author | Kudryk, Ya.Ya. Slipokurov, V.S. |
| author_facet | Kudryk, Ya.Ya. Slipokurov, V.S. |
| citation_txt | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes / Ya.Ya. Kudryk, V.S. Slipokurov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2019. — Т. 22, № 2. — С. 193-200. — Бібліогр.: 39 назв. — англ. |
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| description | In this paper, a review of microwave avalanche transit-time diode (IMPATT diode) structures has been presented. The structure of an IMPATT diode with a sharp p-n junction on Si has been considered, and the functions of the ohmic contacts have been shown. Physical and technical requirements for contacts have been formulated based on their functional purpose and the existing technological base. A review of existing ohmic contacts and their ranking in terms of suitability and promising use in IMPATT diode has been made. The structure of metallization for the IMPATT diode was chosen in the framework of the specificity of the IMPATT diode operation.
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ISSN 1560-8034, 1605-6582 (On-line), SPQEO, 2019. V. 22, N 2. P. 193-200.
© 2019, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
193
Semiconductor physics
Influence of parameters inherent to ohmic contacts
on properties of microwave avalanche transit-time diodes
Ya.Ya. Kudryk, V.S. Slipokurov
V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine,
45, prospect Nauky, 03680 Kyiv, Ukraine
E-mail: konakova@isp.kiev.ua
Abstract. In this paper, a review of microwave avalanche transit-time diode (IMPATT
diode) structures has been presented. The structure of IMPATT diode with a sharp p-n
junction on Si has been considered, and functions of the ohmic contacts have been shown.
Physical and technical requirements for contacts have been formulated as based on their
functional purpose and the existing technological base. A review of existing ohmic contacts
and their ranking in terms of suitability and promising use in IMPATT diode have been
made. The structure of metallization for IMPATT diode was chosen in the framework of
the specificity of the IMPATT diode operation.
Keywords: avalanche transit-time diode, ohmic contact, annealing temperature, current
transfer mechanism.
https://doi.org/10.15407/spqeo22.02.193
PACS 73.40.Ns, 85.30.Kk
Manuscript received 23.04.19; revised version received 15.05.19; accepted for publication
19.06.19; published online 27.06.19.
1. Introduction
The development of semiconductor microwave
electronics requires an increase in the output power of
solid-state microwave-wave generators. Modern
avalanche transit time diodes (IMPATT diode) operate in
this frequency range of output power of the order of
≥10 W in the pulsed mode. To achieve such initial
parameters, there arises the need to use stable ohmic
contact with multilayer metallization with the specific
contact resistance of the order of ρc ≤ 10
–5
Ohm·cm
2
. An
important factor for the use of high-power pulsed
IMPATT diode in microwave circuits is account of the
specific features of the thermal mode of the diode. To
avoid overheating the diode in the pulsed mode, it is
necessary to take into account the influence of the
specific contact resistance not only on the output
parameters, but also on the heating of the semiconductor
part of the diode. When developing an ohmic contact,
one should take into account the specifics of its use in a
specific semiconductor device and its influence on the
main parameters of the device, on the basis of which the
requirements for the contact are formulated. Usually, it is
not possible to create ohmic contact, a resistance of
which is much smaller than that of the base area, the
temperature dependence of the specific contact resistance
affects the temperature dependence of the IMPATT diode
output parameters, generation frequency and power.
Therefore, one of the important requirements for the
ohmic contact to IMPATT diode is a weak temperature
dependence.
2. The principle of action of the avalanche transit-
time diode
Operation of avalanche transit-time diodes is based on
the appearance of a negative differential resistance
(NDR) region in voltage-current characteristic (VCC) of
the inversely shifted p-n junction at the breakdown
section, when a certain value of current exceeds the
critical one [1, 2]. The negative differential resistance is
associated with that voltage and current are in the
opposite phase in a certain period of time. The delay in
the avalanche increase in the amount of carriers is
manifested by the final time of the avalanche current rise,
and the delay in passage of an avalanche through the
semiconductor structure – due to the final time of carrier
passage in the drift region. NDR appears at such a
frequency that the sum of these time intervals is equal to
the half-period of oscillation. On the inverse VCC, one
can observe a downward area, which is called the area
with a negative differential resistance.
The paper [3] shows possible types of IMPATT
diode. Therefore, as a model, the silicon biavalanche
transit-time diode with homogeneous doping the
avalanche areas was taken.
SPQEO, 2019. V. 22, N 2. P. 193-200.
Kudryk Ya.Ya., Slipokurov V.S. Influence of parameters inherent to ohmic contacts …
194
3. Influence of ohmic contacts on the output
characteristics of avalanche transit-time diodes.
Physical and technical requirements to contacts for
silicon subTHz IMPATT diode
When developing the ohmic contact, it is necessary to
take into account specificity of its use in a particular
semiconductor device and its influence on the basic
parameters of the device, on the basis of which the
requirements for contact are formulated. Let us consider
the basic requirements for ohmic contact for IMPATT
diode. Let’s consider the distribution of heat along the
structure of IMPATT diode (Fig. 1). The heat flux is
mainly generated in the band of p-n junction and is
removed through the lower ohmic contact into a massive
heat sink.
The main parameter of IMPATT diode is the
maximum generation power at the optimal frequency
Pout, which depends on the applied power Рin and
efficiency η that weakly grows with increasing the
temperature T [4]:
( )TPP η= inout . (1)
The maximum operation power that can be applied
to the IMPATT diode Рin is determined using the
formula:
( ) ( )η−−= 1jcasemaxin cthj RTTP , (2)
where Tcase is the body temperature; Rth jc. – thermal
resistance of the p-n junction body; Tj max – maximum
operation temperature on the p-n junction, at which the
set operation time up to failure is provided. This
temperature may be limited by the temperature of
degradation of the ohmic contact [5].
The thermoelectrophysical processes in the p-n
junction can also limit the operation temperature of the
p-n junction. Operation of IMPATT diode in the constant
mode was modeled up to the temperature 277 °C [6], and
it was shown that the efficiency of IMPATT diode
increases before 227 °C, but with increasing the tem-
perature to 277 °C the efficiency begins to fall sharply.
Fig. 1. Typical IMPATT DIODE design.
For silicon impulse IMPATT diode, it is usually
recommended the limit operation temperature of the p-n
junction is not higher than 250 °C at a generator
temperature of 50 °C. Also, for the pulsed mode,
operation of IMPATT diode is recommended at 350 °C
[7], which indicates the possibility of operation at this
temperature also in the constant mode under condition of
stable ohmic contact. It allows maximizing the output
power of the device, despite the decrease in efficiency. It
is worth noting that the temperature of the resistance to
overheating (which may occur, for example, when
soldering the device, impulse overloads) and the
maximum operation temperature differ considerably. To
evaluate the required resistance temperature of the ohmic
contact to overheating one can use the known
dependence between the temperature and average
operating time to failure in silicon: with a decrease in
temperature by 40 degrees, the average operation time to
failure increases by an order of magnitude. That is,
without even considering other mechanisms of degra-
dation, in order to provide 10,000 hours of the operation
time to failure, the temperature of contact stability during
rapid thermal annealing must be higher than the
maximum operation temperature by ∆TAr = 230 degrees.
That is, in order to the ohmic contact does not limit the
maximum parameters of the silicon IMPATT diode in the
constant mode of operation, it must be resistant to rapid
thermal annealing at the temperature Тmах = 250 °С +
+ 230 °С = 480 °С. Although the upper contact is under
more unfavorable temperature conditions, however, less
stringent conditions regarding the thickness of the
junction are placed to it as compared to the lower contact,
which in our case makes it possible to form contact
through a simplified procedure without degrading the
IMPATT diode parameters. In order to clarify the
temperature of degradation of the lower ohmic contact, it
is necessary to take into account the temperature drop on
the semiconductor thickness.
Since the main source of heat release is the p-n
junction region, then the thermal resistance consists of
the thermal resistance of p-p
+
sections and the thermal
resistance spreading in copper. Contributions from the
thermal spreading resistance in copper heat sink in Rth Cu
and in p-p
+
sections (Rth Cu) are related to the size and are
calculated by the formula:
S
rh
RRR ththth
+=+=
CuSi
2
CuSi
λλ
, (3)
where S is the area of the diode mesastructure, λSi, λCu are
the coefficients of thermal conductivity of silicon
and copper, respectively, λSi = 0.8 W/cm·deg, λCu =
= 3.9 W/cm·deg; r – radius of the diode mesastructure;
the thickness of the p-p
+
areas h2 = 1.5 µm. For
comparison, Rth Si = 0.41 deg/W; Rth Cu = 6.8 deg/W.
When using not copper, but diamond heat sink Rth diamond
= 2.6 deg/W. Accordingly, the temperature at the ohmic
SPQEO, 2019. V. 22, N 2. P. 193-200.
Kudryk Ya.Ya., Slipokurov V.S. Influence of parameters inherent to ohmic contacts …
195
contact Тcon will be lower than that in the p-n junction
area and equals:
( ) Cuincasecon 1 thRPTT η−+= . (4)
At the temperature near the p-n junction
Tj max = 250 °С, the temperature at the ohmic contact will
be:
( )
CuSi
Cu
casemaxcasecon
thth
th
j
RR
R
TTTT
+
−+= . (5)
In regard to a copper heat sink, Tcon = 236 °С, for a
diamond one Tcon = 217 °С. The required maximum
temperature of rapid thermal annealing without
degradation of the contact will be:
( ) Ar
CuSi
Cu
casemaxmax T
RR
R
TTTT
thth
th
jcaseCu ∆+
+
−+= . (6)
The required maximum temperatures of the rapid
thermal annealing without degradation of the contact for
the lower ohmic contact will be
Тmах Сu = 236 °С + 230 °С = 466 °С;
Тmах diamond = 217 °С + 230 °С = 447 °С.
That is, in both cases the maximum power is limited
by the temperature of the degradation of the ohmic
contact.
Of course, this estimate does not take into account
the geometric factor. For example, the conicity of the
structure leads to a some decrease in the thermal
resistance of the p
+
-layer, limited by the length of the
heat sink. A more radical way to reduce thermal
resistance is multi-mesa compositions. Calculation of the
thermal resistance of a multi-mesa compositions is listed,
for example, in [7], where, due to multi-mesa
composition at a frequency of 60 GHz, the output of
continuous power at the level of 1 W is reached, which
corresponds to the modern level of output power of
IMPATT diode with diamond heat sink. However, such a
construction introduces additional inductance in series,
which may limit its use with frequency growth.
The requirement for the highest possible
temperature stability of contacts to the rapid thermal
annealing is not the only requirement for them. An
important technological parameter is the thickness of the
junction area. Under the thickness of the junction area,
we will understand the depth of penetration of the contact
material into the bulk of semiconductor during the
forming annealing, as well as the defects caused by this
process. The value of the junction area of the ohmic
contact should be much less than the thickness of the
high-doping layer (p
+
-area), in order to prevent
contamination of the drift area with the contact material
and germination of defects into the active area. On the
other hand, an increase in the thickness of the p
+
-area
causes not only an increase in the active electric
resistance, but also an increase in the thermal resistance
(see formula (3)), which reduces the maximum output
power.
Therefore, ideally, the thickness of the p
+
-area
should be much smaller than the thickness of the p-area.
The thickness of the p-area falls with the frequency [8]:
for IMPATT diode at 95 GHz – 0.3…0.38 µm, at
220 GHz – 0.16 µm, i.e., it is desirable to limit the
thickness of p-area with the value of 0.2 to 0.12 µm,
respectively. On the other hand, requirement of a thin
junction layer is limited by the requirement of good
adhesion, that is, the interpenetration of the materials of
contact and semiconductor should provide their good
mechanical adhesion, which will not degrade under the
influence of mechanical stresses that will arise during
operation due to the difference in the coefficients of
thermal expansion for the materials of contact and
semiconductor.
These considerations concern only the lower ohmic
contact, to the upper contact such strict conditions are not
placed. However, for technological reasons, metallization
of the upper contact should not increase the amount of
materials needed to form the contacts, that is, it consists
of the same layers contained in the lower contact.
Consider also the requirements for the specific
resistance of ohmic contacts to IMPATT diode. With an
increase in the resistance in series Rs that is the sum of
the resistance in series of the diode base and the contact
resistance Rs = Rss + Rc, the negative differential
conductivity G becomes closer to zero [9]:
( ) ( )
ms
smsmsms
m GR
CRGRGRGR
G
G
8
2162323 222
ω+−+−+
= , (7)
where Gm is the idealized negative differential
conductivity, provided Rs = 0, ω – cyclic frequency, C –
capacitance. Let introduce the substitution smRG−=α
and quality factor
mG
C
Q
ω
−= [10]. The quality factor Q
gives information about the threshold and the rate of
oscillation growth when IMPATT diode is used for
generation.
( )
8
2
9
32
9
41
9
41
8
3
8
3
,
2
2
1 +−+
α
−
α
−
α
=≡αβ −
QGGQ m
. (8)
When Rs = 0, the variable α is converted to 0, the
efficiency is maximal. When Rs grows to the limit where
α converts to 1, the efficiency decreases to 0. When Gm is
constant, sRG 1∝
Then, the drop of the efficiency (relative to some
ideal efficiency at Rs = 0) depends on the resistance in
series as follows:
SPQEO, 2019. V. 22, N 2. P. 193-200.
Kudryk Ya.Ya., Slipokurov V.S. Influence of parameters inherent to ohmic contacts …
196
0.0 0.1 0.2 0.3 0.4 0.5
0
20
40
60
80
100
5
3 2.5
Q=2
Q=1
η
,
%
α
Q=1.5
Fig. 2. Dependence of the efficiency on α.
( )222
2
max
1
4
27
CRGRG
G
G
GP
P
ss
mm
t ω−−
−==η . (9)
We get the efficiency as a function of two variables
– α and Q:
( ) ( )222
1
4
27
Qt α+αβ+ββ−=η . (10)
Characteristic Q-values for silicon biavalanche TTD
at 95…98 GHz are equal to 3.3…3.8, and the resistance
in series of base reaches (6.7…8.7)·10
–6
Оhm·сm
2
[11].
As you can see from Fig. 2, in order to minimize the
effect of the ohmic contact on the characteristics of
IMPATT diode, the specific resistance of the contact
should be much less than the resistance in series of base
caused by other factors. Technological expedient of
formation of the p
+
-area in the conical form somewhat
reduces the requirements to contact [11], since increases
its area in comparison with the area of the p-n junction.
However, in terms of contact resistance and in terms of
thermal resistance, their contribution is limited to the
length of spreading. Take, for example, the concentration
in the p
+
-area 10
20
сm
–3
. In this case, the length of
transfer will be
s
c
t
h
L
ρ
ρ
= , (11)
where ρs is the specific resistivity of semiconductor in the
p
+
-area, h – thickness of the p
+
-area.
At the thickness h = 2·10
–5
сm, the specific
resistance 10
–3
Ohm·cm, and the specific contact
resistance ρs = 10
–6
Ohm·cm
2
, the gain to the radius is
about 1.4 µm, which will give a gain in the area at the
diameter 35 µm no more than 17%.
Since it is usually not possible to create an ohmic
contact, which resistance would be neglected in
comparison with the resistance of base area, the
temperature dependence of the specific contact resistance
influences the temperature dependence of the initial
parameters of IMPATT diode, generation frequency
and power. Therefore, one of the important requirements
for ohmic contact to LPD is a weak temperature
dependence.
The main feature in operation of active microwave
elements based on IMPATT diode is that the mode of
microwave generation is quite sensitive to the presence
of hetero-geneity of various origin: dislocations,
aggregations of structural defects both in the operation
layer and in the metal-semiconductor contact. The active
part of the diode is actually located in the near-surface
layer of semiconductor, and even a small dispersion of
structural properties (for example, near-surface
microstresses) is sufficient enough that the IMPATT
diode parameters are substantially deviated from the
calculated ones or ultrahigh-frequency generation did not
occur at all. Therefore, else one important parameter of
ohmic contact is the level of internal mechanical stresses,
boundary defectness and defectness at the metal-
semiconductor interface.
4. Requirements for ohmic contacts in IMPATT diode
Being based on the abovementioned, we formulated the
requirements for the ohmic contact, the fulfillment of
which is necessary for its successful use in silicon
IMPATT diode in the ultrahigh-frequency range:
• specific contact resistance is not higher than
10
–6
Ohm·cm
2
;
• weak temperature dependence of the specific
contact resistance;
• temperature stability is not worse than up to
350 °С [5] (optimally to 466 °С);
• contact should also be stable to the influence of
other degradation factors that may occur during its
operation (radiation and ultrasound radiation, thermal
cycling);
• metal-semiconductor contact boundary (<100 nm)
that is thick and homogeneous in morphology and phase
composition;
• good adhesion;
• minimization of internal mechanical stresses at the
metal-semiconductor interface;
• the processes of formation of a contact must be
compatible with the technological scheme of formation
of the device itself.
To obtain recommendations for creating the optimal
contact in silicon IMPATT diode, a review of the
literature data on the properties of the formed ohmic
contacts to silicon was made, which is given below.
SPQEO, 2019. V. 22, N 2. P. 193-200.
Kudryk Ya.Ya., Slipokurov V.S. Influence of parameters inherent to ohmic contacts …
197
5. Modern level of ohmic contact technology
One of the main parameters of ohmic contacts is the
value of resistivity. The minimum value of the specific
resistance depends on the current flow mechanism
through the metal-semiconductor structure. Through the
ideal metal-semiconductor contact, the following current
flow mechanisms are possible [12, 13]:
1. Thermoelectric current flow mechanism.
2. Thermal field mechanism of current flow.
3. Field mechanism of current flow.
4. Current flow in metal shunts.
This approach allows us to determine the dominant
current flow mechanism at the temperature T.
Figs 3 and 4 show the results of using different
types of metallization to form an ohmic contact in the
system of dependence of the specific contact resistance ρc
on the concentration of both donor (Nd) and acceptor (Na)
10
18
10
19
10
20
10
21
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
ρ
c
,
O
h
m
·c
m
2
N
d
, cm
-3
Ti/Au
TiSi
2
/TiN/Al
(Ti-W)/Al
Ti/Al
Ti/Al
Ti/W/Al
TiN
Ti
Pd
2
Si/Al
Pd
2
Si/Ti/Au
Pd/Ti/Au
Pt/W
Pt
PtSi/(Ti-W)/Al
W/Al
Al
Zr
Hf
V
Mg
Ag
ρ
c min
Fig. 3. Results of the use of metallization to form the ohmic
contact in the system to plot the dependence of the specific
contact resistance ρc on the concentration of donor impurity
(Nd) [14-29].
10
18
10
19
10
20
10
21
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
ρ
c
,
O
h
m
·c
m
2
N
a
, cm
-3
NiSi
NiSi
2
TiSi
2
CoSi
2
Pt
Zr
Hf
V
Ti
W/Al
PtSi/W/Al
Al
W
Fig. 4. The results of using metallization to form an ohmic
contact in the system to plot the dependence of the specific
resistance ρc on the concentration of acceptor impurity (Nа)
[20, 26, 29, 30, 32-39].
impurities. The solid line indicates the minimum contact
resistance calculated with account of the three
above-mentioned current flow mechanisms. The dashed
line indicates the maximum permissible resistance of
ohmic contacts for IMPATT diode in the millimeter
wavelength range. Further, we will consider only
contacts with the values of the contact resistance below
this line, i.e., with the specific resistance not higher than
10
–6
Оhm·сm
2
.
Previously, we can see that only ohmic contacts to
the highly doped silicon satisfy the requirement of
minimum contact resistance, which makes the presence
of n-n
+
and p-p
+
steps in the design of the IMPATT diode
mandatory. As shown in Figs 3 and 4, the above
requirement satisfies the contacts on the basis of metals:
platinum, aluminum, zirconium, vanadium, tungsten;
silicides: of titanium, platinum, nickel, cobalt. Deposition
of finished silicides often gives preference in the
thickness of the interface of the annealed contact.
200 300 400 500 600 700 800 900
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
ρ
c
,
O
h
m
·c
m
2
Ti/Au
TiSi
2
/TiN/Al
(Ti-W)/Al
Ti/Al
Ti/Al
Ti/W/Al
Ti
Pd
2
Si/Ti/Au
Pd
2
Si/Al
Pt/W
PtSi/(Ti-W)/Al
W/Al
Zr
Hf
V
T,
o
C
Fig. 5. The dependence of the specific contact resistance (ρc) on
the annealing temperature (T) of the silicon n-Si ohmic contacts
[20, 24, 27, 31, 34-39].
200 300 400 500 600 700 800 900
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
ρ
c
,
O
h
m
·c
m
2
NiSi
NiSi
2
TiSi
2
CoSi
2
Pt
Zr
Hf
V
Ti
W/Al
PtSi/W/Al
T,
o
C
Fig. 6. The dependence of the specific contact resistance (ρc) on
the annealing temperature (T) of the silicon p-Si ohmic contacts
[20, 31, 34, 35].
SPQEO, 2019. V. 22, N 2. P. 193-200.
Kudryk Ya.Ya., Slipokurov V.S. Influence of parameters inherent to ohmic contacts …
198
When forming the ohmic contact to semiconductor,
the following concepts and their combinations are
generally used.
First, it is possible to select the work function in
contact materials, so that, for n-type semiconductor, the
work function of electrons from metal or compound that
was formed during the annealing, φm, must be less than
that from semiconductor, φs, and between metal and
p-type semiconductor qφm > qφs. However, this relation is
true provided when the junction layer is absent, and the
density of surface states at the interface is relatively low.
At high levels of surface density, the Fermi level is fixed,
and the barrier height is weakly dependent on qφm ,
which corresponds to the Bardeen limit. The density
of surface states can be largely changed by the
technological treatment of a semiconductor plate before
and after deposition of an ohmic contact. In other words,
the set of technological conditions for preparation of the
semiconductor surface, methods of deposition and
parameters of annealing, to a large extent, can define the
specific resistance of the contact.
Secondly, extreme doping of a thin surface layer of
semiconductor to provide conditions for tunneling
current. These contacts do not require, at least in theory,
thermal annealing. However, in practice, most of them
are subjected to additional annealing to achieve a
minimum value of contact resistance and maximum
temperature stability. Another way of obtaining the
doped surface layers is to dope the surface from an
external source of doping impurity. Doping can also be
achieved by ion implantation of the corresponding types,
but it leads to the following problems: increased
defectness of the near-surface layer and loss of
stoichiometry.
Technology of manufacturing ohmic contact, as a
rule, is a set of compromise solutions between adhesion
and diffusion permeability of the anti-diffusion layer,
between the value of the contact resistance and thickness
of the junction layer, temperature stability and others.
[38, 39]. Depending on the purpose of the contact and the
requirements for its parameters, it can consist of one or
more layers having different functional values.
In all the above-mentioned current flow
mechanisms, to achieve a low value of the specific
contact resistance is possible by reducing the height of
the potential barrier at the interface of the contact-
forming layer/semiconductor.
Technology of diffusion ohmic contact consists of
formation of thin strongly doped n
+
- and p
+
-layers (steps
of doping) at the contact-semiconductor interface. They
are usually formed during diffusion or ionic doping of
the near-contact area of semiconductor with further
metallization.
In Figs. 5 and 6, in the system of dependence of the
specific contact resistance from the annealing
temperature, the results of formation of ohmic contacts
with different levels of doping of n- and p-type silicon,
respectively, are shown. It is evident that as contact-
forming layer the following refractory materials – V, Hf,
Zr, Ti, W, PtSi, WSi – satisfy the requirements of
resistivity and heat resistance.
6. Conclusions
From the analysis of literature data and our calculated
ones, we can draw the following conclusions:
1. Due to well-developed technology, silicon
ultrahigh-frequency IMPATT diodes in the range 80 to
400 GHz are currently the leaders in output power among
solid-state small-size generators.
2. A further increase in the power and frequency
generation of IMPATT diode puts new demands to
ohmic contacts. On the basis of the analysis of literary
data and own calculations, a model of the influence of
the ohmic contact parameters on the output power of
IMPATT diode: the maximum temperature of rapid
thermal annealing (formulae (1) to (6)), the thickness of
the junction layer and p
+
(n
+
) area as an addition to the
thermal resistance (formulae (1)–(3)), the specific contact
resistance and resistance of p
+
(n
+
) area as an addition to
the basis active resistance (formulae (1), (10)).
3. The technical requirements to ohmic contacts for
IMPATT diode of the ultrahigh-frequency range have
been formulated, the review of the literature data on the
formed contacts has been performed.
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Authors and CV
Ya.Ya. Kudryk, Senior researcher at
the V. Lashkaryov Institute of
Semiconductor Physics. The area of
his scientific interests includes solid
state physics, transport properties in
metal-semiconductor contacts to SiC,
GaN, GaP, InP.
V.S. Slipokurov, Researcher at the
V. Lashkaryov Institute of
Semiconductor Physics. The area of
his scientific interests includes solid
state physics, transport properties in
ohmic contacts to silicon.
|
| id | nasplib_isofts_kiev_ua-123456789-215465 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1560-8034 |
| language | English |
| last_indexed | 2026-03-23T18:52:44Z |
| publishDate | 2019 |
| publisher | Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| record_format | dspace |
| spelling | Kudryk, Ya.Ya. Slipokurov, V.S. 2026-03-18T11:39:14Z 2019 Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes / Ya.Ya. Kudryk, V.S. Slipokurov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2019. — Т. 22, № 2. — С. 193-200. — Бібліогр.: 39 назв. — англ. 1560-8034 PACS: 73.40.Ns, 85.30.Kk https://nasplib.isofts.kiev.ua/handle/123456789/215465 https://doi.org/10.15407/spqeo22.02.193 In this paper, a review of microwave avalanche transit-time diode (IMPATT diode) structures has been presented. The structure of an IMPATT diode with a sharp p-n junction on Si has been considered, and the functions of the ohmic contacts have been shown. Physical and technical requirements for contacts have been formulated based on their functional purpose and the existing technological base. A review of existing ohmic contacts and their ranking in terms of suitability and promising use in IMPATT diode has been made. The structure of metallization for the IMPATT diode was chosen in the framework of the specificity of the IMPATT diode operation. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Semiconductor physics Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes Article published earlier |
| spellingShingle | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes Kudryk, Ya.Ya. Slipokurov, V.S. Semiconductor physics |
| title | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| title_full | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| title_fullStr | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| title_full_unstemmed | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| title_short | Influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| title_sort | influence of parameters inherent to ohmic contacts on properties of microwave avalanche transit-time diodes |
| topic | Semiconductor physics |
| topic_facet | Semiconductor physics |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/215465 |
| work_keys_str_mv | AT kudrykyaya influenceofparametersinherenttoohmiccontactsonpropertiesofmicrowaveavalanchetransittimediodes AT slipokurovvs influenceofparametersinherenttoohmiccontactsonpropertiesofmicrowaveavalanchetransittimediodes |