Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

Contents lists available at SciVerse ScienceDirect

Nuclear Instruments and Methods inPhysics Research A
journal homepage: www.elsevier.com/locate/nima

Evaluation of test structures for the novel n+-in-p pixel and strip
sensors for very high radiation environments
Y. Unno a,g,n, S. Mitsui g, R. Hori a, Y. Ikegami a, S. Terada a, S. Kamada b, K. Yamamura b,
K. Hanagaki f, K. Hara i, O. Jinnouchi h, N. Kimura j, K. Nagai i, I. Nakano e, S. Oda d,
R. Takashima c, Y. Takubo a, J. Tojo d, K. Yorita jaInstitute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi 305-0801, Japan
Solid-state Division, Hamamatsu Photonics K.K., 1126-1 Ichino-cho, Higashi-ku, Hamamatsu-shi 435-8558, Japanc
Department of Education, Kyoto University of Education, 1 Fukakusa-Fujimori-cho, Fushimi-ku, Kyoto 612-8522, Japand
Department of Physics, Kyushu University, 6-10-11 Hakozaki, Higashi-ku, Fukuoka-shi 812-8581, Japane
Department of Physics, Okayama University, 3-1-1 Tshushima-naka, Kita-ku, Okayama-shi 700-8530, Japanf
Department of Physics, Osaka University, Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043, Japang
The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba-shi 305-0801, Japanh
Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japani
Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi 305-8571, Japanj
Research Institute for Science and Engineering, Waseda University, 1-6-1 Nishi-Waseda, Shinjuku-ku, Tokyo 169-8050, Japanb

art ic l e i nf o

Keywords:
Silicon sensor
Pixel
Strip
n-in-pp-typeRadiation damagea b s t r a c t
Radiation-tolerant n+-in-p silicon sensors were developed for use in very high radiation environments.
Novel n+-in-p silicon strip and pixel sensors and test structures were fabricated, tested and evaluated, inorder to understand the designs implemented. The resistance between the n+ implants (interstrip
resistance), the electric potential of the p-stop, and the punch-through-protection (PTP) onset voltage
were measured before and as a function of ﬂuence after irradiation. The technology computer-aided
design (TCAD) simulations were used to understand the radiation damage and ﬂuence dependence of thestructures. The decrease in the interstrip resistance is a consequence of increased leakage current. The
decrease in the electric potential of the p-stop results from a build-up of positive charge in the silicon–
silicon oxide interface. The decrease and subsequent increase in the PTP onset voltages results from theinterface charge build-up and an increase in acceptor states.
& 2013 Elsevier B.V. All rights reserved.

1. Introduction
We have developed n+ readout in p-type bulk silicon, so calledn -in-p, silicon planar pixel and microstrip sensors with highradiation tolerance. These sensors have applications in highradiation environments such as the high-luminosity large hadroncollider (HL-LHC) [1].
The signal readout from n+ implants in p-type bulk has anumber of beneﬁts such as collecting electrons, no type-inversionof the bulk (see Section 2), as opposed to conventional p+ readoutor n-type bulk sensors. There are, however, issues. The main issue
is isolating the n+ implants together with operating at highvoltage. The isolation is achieved by a positive ion implantation
between the n+ implants. In addition, the pixel and strip sensors+

nCorresponding author at: Institute of Particle and Nuclear Study, High Energy
Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi 305-0801, Japan.
Tel.: +81 298645791.
E-mail address: yoshinobu.unno@kek.jp (Y. Unno).

require other structures to make them a practical sensor. These
include a biasing structure and associated punch-throughprotection (PTP) structures.
To work effectively in high radiation environments the structures must be robust against radiation damage and high voltage.
Change in behaviors resulting from radiation damage needs to beunderstood. In this paper, we present experimental results showing the inter-strip resistances, the electric potential of the p-stop
implants, and the PTP onset voltages of our structures as afunction of ﬂuence of particles. The results are understood using
TCAD simulations.
2. n+-in-p sensors and test structures
The radiation species considered in HL-LHC include charged
particles (e.g., protons and pions), γs and neutrons. Particle ﬂuenceis on the order of 1016 1-MeV neutron equivalent particles per
centimeter squared (neq/cm2) in charged particles, 3  106 Graydose in γs equivalent, and 5  1014 neq/cm2 in neutrons. Charged

0168-9002/$ - see front matter & 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.nima.2013.04.075

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i

2

Y. Unno et al. / Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

particles can cause radiation damage in bulk silicon and at theinterface between silicon (Si) and silicon oxide (SiO2). γs causeradiation damage at the Si–SiO2 interface and neutrons cause
damage in bulk silicon.
n+-in-p sensors have a number of beneﬁts: n+-in-p sensors
have a high tolerance against radiation damage in their bulk
silicon. The radiation damage acts to increase acceptor-like levels,
making the p-type bulk to become more p-type [2]. The n+
implants are always being the p–n junction and collecting electrons. The signals induced in the n+ implants are larger due to thestronger electric ﬁeld in the junction, the faster electrons, andreduced trapping of the faster electrons. n+-in-p sensors arecheaper. Lithographic patterning is required only on the readoutside (single-side process). The single-side process allows more
foundries and capacity to be available worldwide. Large 6-in. ptype wafers with high resistivity, e.g., 4 3 kΩ cm, are more readily
available in industry than the n-type wafers. n+-in-p sensors arerobust against handling and testing as no lithographic patterning
is required on the backside of the sensor.
The major issue of n+-in-p sensor is isolating the n+ implants.
The interface between the silicon and the silicon oxide (SiO2) layer
becomes positively charged after the sensor-fabrication process
and from radiation damage by charged particles or γs. The positive
charges at the interface attract negative carriers in the bulk to thesurface of the silicon wafer, creating an inversion layer, shortcircuit the n+ implants, and destroy the isolation required for thesegmented sensors. A p+ ion implantation is required to mitigate
the inversion layer. This can be made with the form of a conﬁned
pattern known as a p-stop structure made by using a mask or withimplantation over the wafers known as p-spray. The implantation
structure is designed so that breakdown occurs at a higher voltage
than the operation bias voltage, e.g., up to 1000 V.
In addition to the speciﬁc n+-in-p structure, the sensor requires
other structures to make it useful for practical applications. A biasing
structure is needed so that the bias voltage is applied to the implants
at high resistance. The high resistance is required to keep theisolation of the implants. For an AC-coupled strip sensor, where
the implant is coupled to the readout metal with a capacitor, aprotection structure can be integrated to limit the drop of thepotential of the implant. When high numbers of charges aredeposited into the bulk due to accidental splashing of beam particles
into the silicon bulk, a large current is induced, which ﬂows throughthe bias resistor and generates a large voltage drop at the implant.
The readout metal is grounded so a large voltage drop may result incapacitor breakdown. The PTP structure keeps the implant voltage
low, by ﬂowing the current though the structure at the bias voltage
greater than the PTP onset voltage, avoiding breakdown.
Novel n+-in-p strip and pixel sensors were fabricated at
Hamamatsu Photonics [3] using 6-in., p-type, ﬂoat-zone, 〈100〉silicon wafers with a resistivity of ∼7 kΩ cm and a thickness of
320 μm [4,5]. A number of miniature 1 cm  1 cm sensors were
included for irradiation and testbeam studies along with large
9.75 cm  9.75 cm area sensors with a 4 segment strip arrangement: two axial strips (1282 strips each, 74:5 μm pitch) and twostereo strips (40 mrad inclined) segments [4]. The miniature
sensors were using common or individual p-stop, or p-spray
isolation structures and polysilicon resistor biasing structure. A
number of ATLAS FE-I3 [6] and FE-I4 [7] ASIC compatible pixel
sensors were implemented using p-stop (common- or individualtype) or p-spray isolation structures and a polysilicon resistor
biasing structure or a punch-through dot at 4-corner of pixels [5].
A number of test structures were made to investigate the electric
potential of the p-stop and the PTP behaviors. These weregenerated in batch 1 at the positions (30–57, 77–89) and (58–71)(see Fig. 1(a) of Ref. [5]). The typical sample parameters are
summarized in Table 1.

Table 1n+-in-p silicon sensor test structure parameters.
Parameters

Samples

TCAD (2D)

Silicon wafer
Wafer type
Crystal orientation
Resistivity
Doping concentration
Thickness

6-in., p-type, FZ〈100〉∼7 kΩ cm–
320 μm

–––4.7  1012 cm−3
150 μmBasic geometry
Strip pitch
Readout metals

74:5 μm
AC coupled, grounded

74:5 μm
AC coupled,grounded
22 μm
GroundedReadout metal widthn+-implants
n+-implant width
Isolation
p-stopP-stop width
Bias resistance

22 μm
Grounded through bias
resistance
16 μm
Common p-stop∼4  1012 cm−2
6 μm
∼1:5 MΩ

16 μm
Common p-stop
4  1012 cm−2
6 μm–

Geometries of the electrical potential of the p-stop
Isolation
Common or Individual p-stop –Strip pitch
30–100 μm–
Geometries of the PTP
n+(strip)–n+(bias rail)
distance
p-stop widthField plate
Field plate coverage

20 μm

20 μm

6 μm
GroundedNo or full

6 μm
GroundedNo or full

3. Test structure measurements
3.1. Irradiation at CYRIC
The test structures were irradiated with 70 MeV protons at
Cyclotron and Radioisotope Center (CYRIC) [8], using the 32 courseand ﬂuences of 5.2  1012, 1.1  1013, 1.2  1014, 1.2  1015, 1.2  1016
neq/cm2 [9] and 1.1  1014, 1.2  1015, 5.7  1015, 1.2  1016 neq/cm2[10]. The irradiations were carried out in an irradiation box, cooled
to approximately −10 1C inside. A number of test structures, 5–10
pieces, were grouped and stacked using paper and polyimide
sheets as separators, and wrapped with polyimide ﬁlms. Becauseof this arrangement, little cooling was expected, despite theassembly being placed in the cooled environment. During theirradiation, the samples increased in temperature. Melting of thepolyimide sheets was observed for samples irradiated at a ﬂuenceof 1016 neq/cm2. After the irradiation the samples were kept in afreezer at −20 1C.
3.2. Interstrip resistance
The resistance between the strips, the interstrip resistance(Rint), was measured using one of the miniature sensors, which
had a strip pitch of 74:5 μm and a common p-stop 6 μm wide. The
electric potential of the center strip V0 was varied between 75 V.
The potential of the two adjacent neighbors that were shorted
externally V1) was measured while changing the potential of the
backplane Vb. The interstrip resistance was calculated using thefollowing equation:
Rint ¼ Rb ðV 0 −V 1 Þ=V 1

ð1Þ

where Rb is the resistance of the bias resistor. Rb was measured tobe ∼1:5 MΩ. The interstrip resistances calculated for the nonirradiated samples and for samples irradiated at ﬂuences of up to
1.2  1015 neq/cm2 are shown in Fig. 1. The interstrip resistanceis plotted as a function of bias voltage. The resistance of the

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i

Y. Unno et al. / Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

Fig. 1. Interstrip resistance as a function of bias voltage for non-irradiated samples(circle) and samples irradiated at 5.2  1012 (square), 1.1  1013 (diamond),
1.2  1014 (cross), and 1.2  1015 (plus).

Fig. 2. Schematic diagram of the miniature sensor used to measure the electric
potential of the p-stop. The inset shows the metal probe connection of the centerprobe point.

non-irradiated sample is seen to ﬂuctuate. This ﬂuctuation is most
likely due to an unknown noise source, since V1 was typically on
the order of μV. The interstrip resistance is seen to decrease from∼1000 GΩ to ∼1 GΩ as the ﬂuence increases.
3.3. Electric potential of the p-stop
The electric potential of the p-stop was measured using test
structures with both common and individual p-stops with various
strip pitches. An example of the test structure used is shown in
Fig. 2. Integrated probing contact is shown in the inset. Measurements were made using a digital voltmeter and a tera-ohm
resistor. The measured electric potential values of the p-stops areshown in Fig. 3. The backplane bias voltage was −500 V. For nonirradiated samples the potential increases with increasing pitch
width and a larger potential is observed for individual p-stops
compared to common p-stops. For increasing ﬂuence, the potential is seen to decrease and eventually saturates between 30 and
40 V.

3

Fig. 3. Electric potential of the p-stop as a function of ﬂuence for a strip pitch andp-stop isolation of 100 μm and common (BZ3-100, circle), 75 μm and common(BZ3-75, square), 30 μm and common (BZ3-30, triangle), 100 μm and individual(BZ2-100, diamond), 75 μm and individual (BZ2-75, cross), 34 μm and individual(BZ2-40, plus). The backplane bias voltage is −500 V.

Fig. 4. PTP onset voltage as a function of ﬂuence for BZ4D-3 (no-gate, diamond)and BZ4D-5 (full-gate, square) structures, and TCAD simulations with no-gate (nonirradiated; triangle) and full-gate (3 points of NBnLTnLC, NBnHTnLC, andDBnHTnHC; cross) structures.

(n+) small enough that the voltage difference between the two
implantations results in a current ﬂow above the punch-throughonset voltage. Our novel PTP structure has an added ﬁeld-plate,which goes from the bias-rail over the PTP gap. This enhances theelectric ﬁeld in the PTP structure due to the electric potential of
the bias-rail: a gate effect. The variation of the onset voltage as afunction of the ﬂuence is shown in Fig. 4. The BZ4D-3 sample is theclassical PTP structure with no ﬁeld plate (no gate). The BZ4D-5
sample is the novel PTP structure with a ﬁeld plate covering thewhole PTP gap (full gate). The results show that PTP onset voltage
decreases by almost half when the ﬁeld plate is added. The same
results are seen both before and after irradiation. This shows thatthe novel PTP structure is effective in inducing onset at lower
voltages. As the ﬂuence increases the PTP onset voltage decreases
ﬁrst and then increases once the ﬂuence reaches approximately
1  1013 neq/cm2.

3.4. PTP onset voltage
4. TCAD simulations
The PTP onset behavior has been measured in various PTP
structures [11,12]. The classical PTP structure is to have a gap
between the bias-rail implantation (n+) and the strip implantation

Semiconductor industries have developed sophisticated semiconductor process and device simulation systems [11]. The

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i

Y. Unno et al. / Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

4

simulation systems are known as Technology Computer-Aided
Design (TCAD) tools and are based on ﬁnite element methods.
We used the simulation tool, Environment for Exploration of
Semiconductor Simulation version 5.5 (ENEXSS 5.5) [13]. ENEXSS
does not include a microscopic model to simulate the irradiatedsilicon devices. Instead, the effective characteristics of the irradiated silicon are approximated: (1) The increase in acceptor statewith increasing Boron doping concentration (Neff). The doping
concentration Neff deﬁnes the resistivity of bulk silicon, which is
the resistance of the non-depleted silicon bulk. (2) The increase inleakage current with increasing generation–recombination rate.
This is simulated by tuning the parameters (An and Ap) of thegeneration–recombination model. (3) The increase in interface
charge with increasing interface ﬁxed charge (Qﬁx). The TCAD
parameters used to approximate the non-irradiated and irradiatedð∼1  1015 neq =cm2 Þ silicon devices are summarized in Table 2. The
TCAD simulations were made for 2-dimensional cross-section of
the device with a thickness of 1 μm. For simulations, mainly thebasic geometry described in Table 1 was used. The bias voltage ofthe backplane was set to −200 V.
4.1. Shockley–Reed–Hall model
In the ENEXSS simulations, the continuity equations of theelectron and hole current densities, Jn and Jp, are given by
 
 
Jp
∂n
J
∂p
−div n ¼ U; −div
¼U
ð2Þ
∂t
∂t
q
q

Fig. 6. TCAD simulated leakage current as a function of bias voltage for the nonirradiated and irradiated conditions.

The generation–recombination term U given by the Shockley–
Reed–Hall (SRH) model [14] is given by
U SRH ¼n2i −npτp ðn þ ni Þ þ τn ðp þ ni Þð3Þτp ∝Apð4Þ

whereτn ∝An ;and n, p, and ni are the electron, hole, and intrinsic carrier
densities, respectively. An and Ap are scaling parameters.
Table 2
TCAD parameters used to simulate the non-irradiated and irradiated conditions.
Parameters

Non-irradiatedIrradiatedDoping concentration (Neff)
Leakage current (SRH Ap,An)Interface ﬁxed charge (Qﬁx)

4.7  1012 cm−3
1.0
1  1010 cm−2

1.5  10 13 cm−3
1  10−8
1  1012 cm−2

Fig. 7. TCAD simulated interstrip resistance as a function of leakage current.

The variation in the leakage current as a function of theparameters An and Ap is shown in Fig. 5. The leakage currents
varies by 3 orders of magnitude when An and Ap are decreased
from 1.0 to 1  10−8. The current saturates at An and Ap below∼1  10−8 . The simulated leakage current as a function of bias
voltage is shown in Fig. 6. Both non-irradiated and irradiated TCAD
conditions were simulated using the parameters in Table 2 and theinterstrip resistance geometry in Table 1.

4.2. Interstrip resistanceFig. 5. TCAD simulated leakage current as a function of the An and Ap SRH scaling
parameters.

The interstrip resistances Rint were simulated for both the nonirradiated and irradiated conditions. In addition, simulations werecarried out for conditions with slightly less leakage current. The
result is shown in Fig. 7. The interstrip resistance decreases by
2 orders of magnitude from the non-irradiated to irradiatedconditions. No decrease in the interstrip resistance is observed if
only the doping concentration or the interface charge is varied.
The decrease in the interstrip resistance therefore results from an

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i

Y. Unno et al. / Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

5

increase in the leakage current due to the radiation damageof bulk.
4.3. Electric potential of the p-stop
The 2-dimensional distribution of electric potential for both
non-irradiated and irradiated conditions is shown in Fig. 8. The
two simulations have distinctive difference. The potential is moreconcentrated toward the n+ implants for the non-irradiatedconditions (Fig. 8(a)) and more uniform between the n+ implants
for the irradiated conditions (Fig. 8(b)). The difference is caused by
the amount of interface charge Qﬁx, 1  1010 cm−2 in the nonirradiated and 1  1012 cm−2 in the irradiated conditions. In theirradiated condition, an electron inversion layer is seen at the Si–
SiO2 interface everywhere except in the vicinity of the p-stop. This
resistive inversion layer extends the electric potential between then+ implants. The electric potential between the implants is shownin Fig. 9. The result for the irradiated condition but with negativeinterface charge of Qﬁx ¼−1  1012 cm−2 is also shown. The results
suggest that the decrease in the electric potential of the p-stop
comes from the increase in the interface charge that is positive.
4.4. PTP onset voltage

Fig. 9. TCAD simulated electric potential of the p-stop for non-irradiated(Qﬁx ¼ +1  1010 cm−2, circle) and irradiated (Qﬁx ¼ +1  1012 cm−2, square and−1  1012 cm−2, triangle) conditions.

In 2-dimensions, the PTP structure is very similar to the basic
geometry. In the PTP structure, the distance between the n+implants of 20 μm was used. The bias rail structure was set in theright-hand n+-implant. The metal over the implant was connected
directly to the implant (DC metal). The ﬁeld plate was made byextending the DC metal toward the left-hand n+-implant over thesurface SiO2. No bias resistor was integrated in parallel to the PTP
gap. The PTP behavior was simulated by varying the electric
potential Vtest of the left-hand implant from 0 V to −200 V, while
maintaining the backplane bias voltage at −200 V.
TCAD simulations were carried out with and without the ﬁeld
plate. These are labeled as full-gate and no-gate, respectively. The
three parameters used to model the radiation damage wereindividually set using the following parameter values: For low(NB) and high (DB) silicon bulk damage Neff was set to
4.7  1012 cm−3 and 1.5  1013 cm−3, respectively. For low (LT) andhigh (HT) interface change Qﬁx was set to 1  1010 cm−2 and1  1012 cm−2, respectively. For low (LC) and high (HC) leakage

Fig. 10. TCAD simulated electric ﬁeld distribution of the PTP structure with a fullgate ﬁeld plate for irradiated condition at an onset voltage of −50 V.

Fig. 8. TCAD simulated electric potential distributions for (a) non-irradiated and(b) irradiated conditions.

current An and Ap were both set to 1.0 and 1  10−8, respectively.
The non-irradiated and irradiated (1  1015 neq/cm2) conditions
were NBnLTnLC and DBnHTnHC, respectively. At low ﬂuence theincrease in interface charge is the dominant factor. The NBnHTnLC
may correspond to the low ﬂuence point, e.g., 5  1012 neq/cm2.
An example of the 2-dimensional electric ﬁeld distribution at
Vtest of −50 V for the full-gate and irradiated simulations is shownin Fig. 10. The PTP has just been turned on. The breakdown occurs
at the highest electric ﬁeld at the right-hand edge of the p-stop.
The PTP behavior is shown in Fig. 11. The PTP onset voltage isdeﬁned as the voltage at the corner where the current starts toincrease rapidly. For the no-gate and non-irradiated condition(NPTP) the onset voltage is around 70 V. For the full-gate and nonirradiated (NBnLTnLC) the onset decreases to around 50 V. Increasing the interface charge (NBnHTnLC) further reduces the onset to

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i

Y. Unno et al. / Nuclear Instruments and Methods in Physics Research A ∎ (∎∎∎∎) ∎∎∎–∎∎∎

6

electric potential of the p-stop, and the PTP onset voltages were
measured as a function of ﬂuence. Radiation damage was approximated in the TCAD device simulations by increasing the acceptor
states, increasing the interface charge, and increasing the leakage
current. The increase in the leakage current was tuned using the
Shockley–Reed–Hall model for the generation–recombination ofelectron–hole carriers. The TCAD simulations were used to understand the ﬂuence dependencies of the devices. The decrease in theinterstrip resistance is a consequence of an increase in the leakage
current. The decrease in the electric potential of the p-stop resultsfrom a build-up in the positive interface charge. The decrease andsubsequent increase in the PTP onset voltages result from theinterface charge build-up and an increase in the acceptor states.

Acknowledgments

Fig. 11. TCAD simulated onset behavior of the PTP structures. (NPTP) nonirradiated without a ﬁeld plate. (NBnLTnLC) non-irradiated with a full-gate ﬁeld
plate, (NBnHTnLC) non-irradiated full-gate with a high interface charge,(NBnHTnHC) irradiated full-gate with no bulk damage, and (DBnHTnHC) irradiatedfull-gate.

around 30 V. Increasing the leakage current (NBnHTnHC) has noeffect on the onset voltage. Increasing the bulk damage(DBnHTnHC) increases the onset voltage to around 50 V. The
simulated onset voltages are plotted in Fig. 4 as a function of
ﬂuence. The decrease and subsequent increase in the onset voltage
as a function of increasing ﬂuence result from a build-up of theinterface charge followed by the increase in the acceptor states.
The systematic offset of the onset voltages between the experimental measurements and the TCAD simulations are thought to bea result of the difference of the 3-dimensional devices and the 2dimensional simulations.
5. Summary
We have developed radiation-tolerant n+-in-p silicon sensors
for use in high radiation environments. Novel n+-in-p silicon strip
and pixel sensors and test structures were fabricated, tested, andevaluated in order to understand the basic characteristics of thedesigns implemented. The resistance between the n+ implants, theThe authors would to thank KEK's Detector Technology Projectfor use of their TCAD program ENEXSS. This research was partially
supported by a Grant-in-Aid for scientiﬁc research (A) (Grant no.
20244038) from the Japan Society for the Promotion of Scienceand a Grant-in-Aid for scientiﬁc research on Innovative Areas(Grant no. 23104002) from the Ministry of Education, Culture,
Sports, Science and Technology.
References[1] 〈http://hilumilhc.web.cern.ch/HiLumiLHC/index.html〉.
[2] S. Terada, et al., Nuclear Instruments and Methods in Physics Research Section
A 383 (1996) 159.
[3] K.K. Hamamatsu Photonics, 1126-1 Ichino-cho, Hamamatsu-shi, Shizuoka,
Japan, 435-8558.
[4] Y. Unno, et al., Nuclear Instruments and Methods in Physics Research Section A
636 (Suppl.) (2011) S24.
[5] Y. Unno, et al., Nuclear Instruments and Methods in Physics Research Section A
650 (2011) 129.
[6] I. Peric, et al., Nuclear Instruments and Methods in Physics Research Section A
565 (2006) 178.
[7] M. Garcia-Sciveres, et al., Nuclear Instruments and Methods in Physics
Research Section A 636 (Suppl.) (2011) S155.
[8] Cyclotron and Radioisotope Center (CYRIC), Tohoku University, Aramaki AzaAoba 6–3, Aoba-ku, Sendai-shi 980-8578.
[9] T. Shinozuka, et al., CYRIC Exp. 9214, July 21, 2010.
[10] T. Shinozuka, et al., CYRIC Exp. 9362, February 22, 2011.
[11] Y. Unno, et al., Proceedings of Science (〈http://pos.sissa.it/〉), POS(Vertex 2011)024.
[12] S. Mitsui, et al., Nuclear Instruments and Methods in Physics Research Section
A 699 (2013) 36.
[13] Hyper Environment for Exploration of Semiconductor Simulation (ENEXSS),developed by a consortium, Semiconductor Leading Edge Technologies, Inc.
(SELETE), 2006/4-2011/3.
[14] W. Shockley, W.T. Reed, Physical Review 87 (1952) 835.

Please cite this article as: Y. Unno, et al., Nuclear Instruments & Methods in Physics Research A (2013), http://dx.doi.org/10.1016/j.
nima.2013.04.075i