Speed Response and Performance Degradation of High Temperature Gamma Irradiated Silicon PIN Photodiodes

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Speed Response and Performance Degradation of High Temperature Gamma Irradiated Silicon PIN Photodiodes Powered By Docstoc
					                                                         (IJCSIS) International Journal of Computer Science and Information Security,
                                                         Vol. 9, No. 5, May 2011

             Speed Response and Performance Degradation of High Temperature
                        Gamma Irradiated Silicon PIN Photodiodes
          Abd El-Naser A. Mohamed1, Nabil A. Ayad2, Ahmed Nabih Zaki Rashed1* and Hazem M. El-Hageen1, 2
                            Electronics and Electrical Communication Engineering Department,
                                  Faculty Electronic Engineering, Menouf, 32951, Egypt
                              Atomic Energy Authority, P.O. Box 29, Naser City, Cairo, Egypt

Abstract─In the present paper, we have been investigated                by the internal field. With no external voltage applied, this
deeply and parametrically the speed response of Si PIN                  internal field will prevent the majority carriers to cross the
photodiodes employed in high temperature-irradiated                     junction. Minority carriers however are still capable of
environment. The radiation-induced photodiodes defects can              reaching the junction by diffusion and give rise to leakage
modify the initial doping concentrations, creating generation-          current. Electron-hole pairs generated outside the depletion
recombination centres and introducing trapping of carriers.
Additionally, rate of the lattice defects is thermally activated and
                                                                        region will most likely recombine, consequently not
reduces for increasing irradiation temperature as a result of           contributing to the photocurrent [3].
annealing of the damage. Nonlinear relations are correlated to                The current–voltage technique is used to measure the rate
investigate the current-voltage and capacitance-voltage                 of carrier creation and so the generation or the recombination
dependences of the Si PIN photodiodes, where thermal and                rate [4]. On the other hand, the capacitance–voltage technique
gamma irradiation effects are considered over the practical             in reverse bias direction, is used to determine doping profiles
ranges of interest. Both the ambient temperature and the                of a semiconductor [4–6]. The capacitance measurements give
irradiation dose possess sever effects on the electro-optical           information about fixed impurity states and defect centers in
characteristics and consequently the photo-response time and            the band gap. Device testing, adequate system shielding and
SNR of Si PIN photodiodes. In this paper, we derive the transient
response of a Si PIN photodiode for photogeneration currents,
                                                                        radiation tolerant design are some fundamental steps in the
when it is exposed to gamma radiation at high temperature. An           methodology or in the radiation hardness assurance [7] that
exact model is obtained, which may be used to optimize the              are needed to ensure the correct performance and efficiency of
responsivity and speed of these irradiated devices over wide            electronics during system life. But, there is an increasing
range of the affecting parameters.                                      interest in the development of accurate modeling and
                                                                        simulation techniques to predict device response under
Keywords: Radiation effects, PIN photodiode, Optoelectronics,
                                                                        different radiation conditions [8].
Transient current, Dark current, Photocurrent, Quantum
efficiency, Responsitivity.                                                   In the present study, we have been investigated and
                                                                        analyzed parametrically and numerically the modeling basics
                   I. INTRODUCTION                                      of a PIN photodiode device with the maximum possible
     Since several years, photonic and lightwave technology             precision, in order to predict the frequency response behaviour
is seriously considered for optical access communication and            of Si PIN photodiodes when they were irradiated to different
monitoring applications in space borne local communication              dose of high-temperature gamma radiation environments over
systems and nuclear projects. A major problem in these                  wide range of the affecting parameters.
environments is the presence of radiation fields. Two types of
damage affect the electronic devices when they are exposed to                        II. Physical Modeling Basics
the radiation [1]. The first one is ionization damage, it is a                Radiation damage produces defects which can result in
transitory damage. In contrast, displacement damage is                  three main effects on photodiode devices as following:
considered permanent. For several reasons, the interest of              - The increase in dark current can be related to the minority
study of the effects of performance of devices in high-                 carrier lifetime of the semiconductor if the generation-
temperature electronics is developing rapidly. If these                 recombination is dominated by mid-band levels caused by
components are to be used in a radiation environment,                   defects. Another source affecting the dark current could be
knowledge about the degradation under high-temperature                  ionizing damage to the surface of the device.
irradiation conditions is highly desirable [2]. Optical                 - Degraded photocurrent as defects act as electron or hole
communication devices in close proximity to radiation fields            trapping centers for the photogenerated pairs. The defects may
such as those present in terrestrial orbits and high-energy             be primary defects, i.e. defects which originate directly from
accelerators suffer both long term effects due to total dose and        atomic displacements, or secondary defects resulting from the
displacement damage from non-ionizing energy-loss, as well              interaction of mobile primary defects with impurities. Many
as short term or transient effects due to local ionization from         defects will recombine leading to an immediate repair of the
nuclear reactions and high-energy recoils generated close to or         lattice. However, some will combine to form stable defects
within the depletion volume of a device. A photodiode works             such as interstitials, di-vacancies, vacancy-impurity
by generating current from photons absorbed in its active               complexes, vacancy-dopant complexes, and larger clusters.
area. In a semiconductor material, a region depleted of                 These defects form effective recombination and trapping
mobile charge carriers is formed near the P-N junction. This            centers resulting in a decrease in the minority carrier lifetime,
zone is called depletion region. Incident radiation within this         carrier density and carrier mobility. Defect centers position in
region will create electron-hole pairs, immediately separated           the band gap determines their activity and hence the

                                                                                                     ISSN 1947-5500
                                                      (IJCSIS) International Journal of Computer Science and Information Security,
                                                      Vol. 9, No. 5, May 2011

conduction mechanism in devices made from such material              the following parameters; type and energy of the incident
[9]. Deep traps are defects whose ionization energy, E, is           particle, kind of material, resistivity, types and concentration
much greater than kBT (kB is the Boltzmann constant and T is         of impurities, injection level, temperature and elapsed time
the temperature). They trap free carriers with the consequence       after irradiation [14, 15]. Also a semiconductor p–n junction
that they reduce the conductivity considerably. In contrast,         acts as a capacitor. The depletion region capacitance of a
shallow traps are easily ionized at equilibrium since ∆E <<          uniformly doped lifetime diode at full depletion may be
kBT, and so they increase the conductivity by releasing              expressed in terms of the dielectric constants ε0, εr. In this
trapped carriers. In depleted regions they contribute to the         situation the effective carrier concentration is evaluated:
space charge and the voltage required for full depletion.                                            2C 2
                                                                                     N eff =                      V                                        (2)
Generation–recombination (g-r) centers are situated near the                                      qε rε 0 A 2
centre of the band gap, in which position their trapping for         Where A is the active diode area, q is the electronic charge
electrons and for holes is comparable, and so they easily            and V is the full depletion voltage. This relation shows that
generate or recombine e–h pairs. Then the free carriers are          Neff α VC2, which may be simplified to V α C−2 for a constant
removed to reduce the conductivity. Defect centers can also          effective carrier concentration, which is the case for uniform
act as compensation centers in the electrical neutral bulk of a      doping and is assumed for lifetime material. In any
semiconductor. Here, the deep levels are not easily ionized at       semiconductor, a rise in temperature will increase the current,
equilibrium and have the effect of locking away free carriers        since carriers become thermally activated to increase the
to reduce the conductivity. The response degradation [8] is          effective carrier density, Neff, so that the current I α Neff. An
probably related to type inversion of the low-doped layer from       increase in light intensity is expected to have the same effect
n to p-type. At low integrated fluence, the radiation forming        [9]. Because the current is ohmic and is generated in the
acceptor state levels compensate the donor states until the          whole of the depletion region, the depletion width becomes a
effective doping concentration Neff is reduced to that of the        function of depletion voltage. The capacitance becomes a
intrinsic semiconductor. At higher fluences, the effective           function of radiation and temperature since electrons and
doping is mainly provided by the radiation induced defects.          holes are thermally activated.
The concentration of majority carriers decreases with the
irradiation fluence.                                                                          III. Modeling Description
- Degraded rise and fall times due to de-trapping or a
reduction in the carrier mobility [10]: The decrease in                           A) Optical and electrical properties analysis
photocurrent and the increase in the dark current are expected       The dark current, ID, for a device having depletion depth W,
to be the major changes in thin junction devices such as             active area A and the effective carrier concentration, Neff
photodiodes. The change in the device response, rise and fall        under high temperature irradiation T and gamma radiation
times are expected to be small, but still require measuring.         fluence γ is given by [15, 16]:
Three main factors limit the speed of response of a                                           qAW (T , γ ) N eff (T , γ )
photodiode. These are [11]:                                                          ID =                                                                  (3)
                                                                                                      2τ r (T , γ )
a) The drift time of the carriers through the depletion region;
b) The diffusion time of the carriers generated outside the          Where τr is the minority carrier lifetime after irradiation and it
depletion region;                                                    is given by [9, 12]:
                                                                                    1/τ r = 1/τ 0 + Kr γ                                                     (4)
c) The time constant incurred by the capacitance of
photodiode with its load and its associated circuit.                 Where τ0 denotes the pre-irradiation minority carrier lifetime
      Photons that penetrate the semiconductor can be                respectively, and Kr is the damage coefficient for τr. Assuming
absorbed and its energy can be utilized in the generation of e–      a linear relationship between damage increase and fluence, the
h pairs. The model that describes the rate of generation is [12]:    damage coefficient for dark current KD and light photocurrent
                                  p α                                KP, can be defined by following equation [15]:
          G opt ( x ) = (1 − r )η 0 exp( −α x )           (1)
                            hν                                                  ΔI D , P = I D , P (γ ) − I D , P (0) = K D , P γ (5 ) A
where r is the reflection coefficient, Previous reports in           simple model of the annealing can be constructed if we
literature have stated that is independent of dose for 1 MeV         assume that the radiation-induced defects anneal according to
electron irradiations up to 5×1015 cm-2 [13]. η is the quantum       a first-order mechanism (exponential recovery) [17], at a
efficiency, P0 is the incident light intensity, h is the Planck      given absolute high temperature irradiation T, KD can be
constant, ν is the photon frequency, α is the absorption             related to an activation energy E by the Arrhenius formula:
coefficient and x is the depth variable. The optical spectral        K D (T ) = K D (0) exp(E / K BT )                                                     (6)
response of a PIN photodiode is called the optical sensitivity       Where KB, is Boltzmann’s constant.
or the responsivity and it is related to the total photon-induced    Based on the data of [18-20], the following nonlinear thermal
current. If the width of the p-layer is much thinner than 1/α,       and radiation relations for the set Si PIN photodiode:
the photon-induced current in the p-layer does not contribute        I Dark    , Photo   ( T , γ ) = I Dark   , Photo    ( T ) × I Dark   , Photo   (γ )   (7)
to the total photocurrent.                                                                                        − 24                         ⎫
                                                                     I Dark     = I Dark ( 0 ) + 3 . 29 × 10              exp( 831
      The      current–voltage       and      capacitance-voltage                                                             T                ⎪
                                                                                                                  ⎛ − 1 . 137 × 10 − 11 T 2 ⎞  ⎪
characteristics, in the dark and under illumination are highly                                                    ⎜                         ⎟
                                                                                                                                               ⎬           (8 )
sensitive to the radiation-induced change of the minority            I Photo    = I Photo ( 0 ) − 7 . 8 × 10 − 14 ⎜ + 6 . 536 × 10 − 9 T ⎟ × γ ⎪
                                                                                                                  ⎜                   −8    ⎟  ⎪
carrier lifetime τ. In general, the damage coefficients for the                                                   ⎜ + 8 . 207 × 10
                                                                                                                                            ⎠  ⎪
mean minority carrier lifetime in semiconductors depend on
                                                                     The drift current density of PIN photodiode is given as:

                                                                                                                    ISSN 1947-5500
                                                                                        (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                        Vol. 9, No. 5, May 2011

           W                                                    qp 0 (1 − r f )                           Where T is the ambient temperature, γ is irradiation fluence,
j drift = q ∫ G opt ( x ) dx =q ϕ 0 (1 − e − α W ) =                              (1 − e − α W ) ( 9 )
               0                                                    ah υ                                  C0/a1=1.176×10-9, a2=0.001052,.β=1.139×10-15 and V=-1volt.
The one-dimension diffusion equation for initial minority                                                 The depletion width W can be expressed as the following [9]
holes Pn0 in the bulk n region is [11, 21]                                                                               2 ε ( V + V bi )
                                                                                                          W =                                    =      2 ερμ ( V + V bi )                ( 21 )
    ∂ 2 pn      pn − pn0                                                                                                      qN eff
DP           −             + G opt ( x ) = 0                                                (10 )
     ∂x 2          τ p                                                                                            ε 0ε r A
                                                                                                          W =                                                                             ( 22 )
          1            pn0     ϕ α −αx                                                                                   C
pn2 − (      ) pn = −        − 0      e                                                     (11)
        L2 p           L2p
                                DP                                                                        Where A is the effective photodiode area, q is the electronic
                                                                                                          charge, Neff is the carrier concentration, εr is the dielectric
               L2            K BT
   Dp =
                        =         μ                                                        (12 )          constant of silicon, ε0 is the vacuum permittivity. From the
               τp              q                                                                          previous results [4, 5], we can observed that εr is constant for
Where τp, LP and Dp are minority carrier life time, diffusion                                             radiation but it is function of temperature as [22]:
length and diffusion constant and μ is the carrier mobility.                                              ε r (T ) Si ≈ 11 . 631 + 1 . 0268 × 10 − 3 T + 1 . 0384 × 10 − 6 T 2
The solution of Eq. 11 under the boundary conditions Pn=Pno                                                                  − 8 . 1347 × 10 − 10 T 3                                  ( 23 )
for x=∞, and Pn=0 for x=W.                                                                                The Tauc model [23] has been used as a stander model
                        Dp                 αL p
j diffu = qp n 0               + qϕ 0 (              ) e −α W                               (13)          whereby the optical gap of an amorphous semiconductor may
                        Lp                1 + αL p                                                        be determined as:
j total = j drift + j diffu                                                                (14 )          α ( hν ) = α 0 ( hν − E g ) 2                                                  ( 24 )
                     αL p − 1 − αL p −αW            Dp                                                    Where 1/α0 is the band edge parameter and Eg is energy gap.
j total = q ϕ 0 (1 +                e    ) + qp n 0                                         (15 )
                         1 + αL p                   Lp                                                    The energy gap of the perfect silicon as a function of the
Under normal operating conditions, the dark-current term                                                  temperature is given by [24]:
involving pno is much smaller so that the total photocurrent is                                                                   4 .731 × 10 − 4 T 2
                                                                                                          E g = 1 .166 −                                                                 ( 25 )
proportional to the incident photon flux per unit area, φ0 .                                                                           636 + T
But under irradiation condition the total photocurrent is                                                 But for imperfect semiconductor as a result of radiation
given by [9]:                                                                                             induced defects the energy band gab Eg is replace by Tauc
I total = I Photo + I Dark                                                                  (16 )         bandgap energy EgTauc [23], then α will became:
Where Itotal is the current measured under illumination, IDark                                            α Tauc (hν ) = α 0 (hν − E g Tauc ) 2                                         (26)
is the current measured in the dark, Iphoto is the current due to                                         In this case the residual absorption near the bandgap due to the
the illumination only. The high-temperature irradiation                                                   intragap is called the Urbach tail [25], and can be expressed
induce diffusion length change can be expressed as the                                                    with the following equation close to the bandgap:
following expression:                                                                                                                            ⎛ (hυ − E g ) ⎞
                        aqp 0 (1 − r f )       e −α W                                                     α Urb ( h υ ) = A 0 exp ⎜
                                                                                                                                                               ⎟                       ( 27 )
I photo = j photo × a =                  (1 −          )                                   (17 )                                                 ⎝    E Urb    ⎠
                             hυ               1 + αL p
                                                                                                          We need a function for α that is valid for the entire spectral
                                      I photo                                                             range, i.e. an equation that combines (15) and (16) is smooth
                       1 − e α W (1 −         )
     ⎛ 1           ⎞                       aq ϕ 0                                                         at the cross point, Ecross:
Lp = ⎜
                   ⎟                                                                       (18 )
                                    I photo                                                               α Tauc ( E cross ) = α Urb ( E cross )                                       ( 28 )
     ⎝ s           ⎠     e α W (1 −         )
                                          aq ϕ 0                                                            ′                    ′
                                                                                                          α Tauc ( E cross ) = α Urb ( E cross )                                       ( 29 )
Where a is the photodiode area. By comparing the different                                                Where α' denotes the first derivative with respect to the
cases of the depletion layer width, the junction capacitance                                              energy. With equations (28) and (29) the following conditions
and the inverse of the absorption coefficient, a reasonable                                               are obtained:
compromise between high-frequency response and high                                                                                 ⎛        ⎛    1                       α0 ⎞⎞
                                                                                                          Eg        = E g − 2 E Urb ⎜ 1 + ln ⎜                               ⎟⎟         ( 30 )
quantum efficiency of photodiode is found for absorption                                                       Tauc                 ⎜        ⎜ 2 E Urb                    A0 ⎟ ⎟
                                                                                                                                    ⎝        ⎝                               ⎠⎠
region thicknesses between 1/α and 2/α.                                                                   EUrb (T ) = E u 0 × T                                                          ( 31)
       W             ⎛                     I photo  ⎞
αW =          = − ln ⎜ (1 + α s L p )( 1 −         )⎟                                      (19 )          Where Tauc and Urbach parameters of silicon material are
     (1 / α )        ⎜                      aq ϕ 0 ⎟
                     ⎝                              ⎠                                                     A0=800cm-1, Eu0=36 Mev [25], and α0=4685cm-1 [26].
Irradiation induced change of the depletion layer width and
the absorption coefficient must be take into consideration.                                                                         B) Photodiode response analysis
Based on Eq.2 and the results of [5, 6] which shows the
variation of the effective carrier concentration, Neff of Si PIN                                          The responsitivity, S, of a PIN photodiode can be expressed
photodiode with electron irradiation dose. The depletion layer                                            as:
                                                                                                                          I photo       qη
capacitance with its initial value C0, when a voltage V is                                                S (T , γ ) =              =                                                     (32) Wh
                                                                                                                             P0         hυ
applied to a junction with the built-in potential (Vbi (Si)~0.65v
[9]), is given by:                                                                                        ere the quantum efficiency, η, can be given by:
                   C0       exp( − βγ )        (1 + a 2 T )                                                                    I photo / q                        ⎛      e −α W    ⎞
C (T , γ ) =                               ×                                               ( 20 )         η (T , γ ) =                               = (1 − R f ) ⎜ 1 −            ⎟     ( 33 )
                             a1                                                                                              P0 (1 − r ) / h ν                    ⎜     1 + αL p   ⎟
                                                V + V bi                                                                                                          ⎝                ⎠
                                                                                                          In order to analyze the response time of irradiated PIN
                                                                                                          photodiode, assume a modulated photon flux density as:

                                                                                                                                                           ISSN 1947-5500
                                                                                     (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                     Vol. 9, No. 5, May 2011

ϕ = ϕ 0 exp( j ω t ) photons /( s .cm 2 )                                             ( 34 )              Where W0 is the substrate thickness. Finally, for fully
To fall on photodiode, where ω is the sinusoidal modulation                                               depleted photodiodes the rise time tr and fall time are
frequency. The total current through the depletion region                                                 generally the same.
generated by this photon flux can be shown to be [21, 27]:                                                         2      2      2
                                                                                                          tr =   t dr + t Df + t RC                                            ( 42 )
          ⎛ jωε ( V + Vbi )        1 − e − jω t dr                 ⎞
                                                                   ⎟ e jω t                               Finally the power signal-to-noise ratio (SNR) S/N at the
J tctal = ⎜                 + qϕ 0                                                    (35 )
          ⎜       W                    jω t dr                     ⎟
          ⎝                                                        ⎠                                      output of an analog optical receiver is defined by [11]:
                     ⎛ ω t dr⎞                                                                                                   0.5m2 I 2
               Sin 2 ⎜
                     ⎜ 2     ⎟
                             ⎟ ⎛ ω ε ( V + V ) ⎞ ⎛ ω ε ( V + V ) ⎞2                                       S/N=                                                                  (43)
 I total             ⎝       ⎠⎜               bi ⎟ ⎜          bi ⎟                                               (2qf−dB(I photo + I Dark) + 4K BTf−dBFn / RL )
           =                    1−                 +                (36 )
 a q ϕ0                     2 ⎜                  ⎟
                                   W (ω t dr ) 2 ⎠ ⎜     W       ⎟
                 ⎛ ω t dr ⎞    ⎝                     ⎝           ⎠
                 ⎜ 2 ⎟    ⎟                                                                               Where m is the analoge modulation index, f-dB ≈ 0.35/tr is
                 ⎝        ⎠
                                                                                                          bandwidth and tr is rise time. The term (4KBTf-dBFn/RL) is the
Where ε is the material permittivity, tdr is the transit drift                                            total noise associated with amplifier, it is referred to thermal
time of carriers through the depletion region is:                                                         noise of load resistor RL by the amplifier noise figure Fn.
t dr = W / 2υ d                                                                        ( 37 )
For p on n devices where W is the width of the depletion
region and υd is the average drift velocity of the carriers. In
terms of measurable components Eq.37 The transit drift time                                                                IV. Results and Discussion
becomes:                                                                                                       Based on the above modeling equations analysis, the
            W 2                                                                                           dynamic electro-optical characteristics of Si PIN photodiode
t dr =                                                                                 ( 38 )
       μ ( V + V bi )                                                                                     are processed in high temperature gamma rays irradiations
Where μ is the carrier mobility.                                                                          fields. The double impact of thermal and radiation effects are
The time for diffusion of carriers from the undepleted region                                             analyzed over ranges of causes (affecting parameters). As
to the depleted region is given by:                                                                       1012> γ, Fluence, e/cm2>1014 and 300>T, Temperature,
           l2                                                                                             K>400. Special software programs are designed, cast and
t Df =                                                                                ( 39 )              employed to handle the given basic model, where variation of
                                                                                                          set of electrical and optical devices parameters {ID, IP, α, η}
Where D and l are the diffusion constant and the
                                                                                                          against variations of a set of two effects {T, γ} are processed.
undepleted thickness, which changes with the changing of
                                                                                                          The device parameters are computed on bases of results of [5,
the depletion layer width W. The time constant tRC of the
                                                                                                          6, 18, 19, 20]. These variations will effect on response time tr,
photodiode with a load resistance RL is given by:
t RC = 2 . 2 (R S + R L ) C                                                            ( 40 )
                                                                                                          responsivity S and signal to noise ratio SNR of the device.
                                                                                                               Based on the assumes set of the operating parameters,
Where C is the capacitance of photodiode at applied bias V,                                               and the equations analysis, then the obtained results are
Rs is the series resistance of photodiode, it is the resistance                                           displays in Figs. (1-7), for the processed Si device of optical
of the contacts and the undepleted bulk of the substrate.                                                 wavelength of λ=950 nm are assured the following facts:
           ρ (W 0 − W )
RS =                                       + contact   resistore                       ( 41 )


                      Responsivity (A/W)





                                                              T=290        K
                                                              T=330        K
                                                              T=370        K
                                                              T=400        K

                                                0.1       1            2         3              4          5          6          7           8           9          10
                                                                              Fluence of Radiation (e/cm2)                                                   x 10
                          Fig. 1. Optical sensitivity of irradiated Si PIN photodiode at various radiation fluence and temperature.

                                                                                                                                                 ISSN 1947-5500
                                                                               (IJCSIS) International Journal of Computer Science and Information Security,
                                                                               Vol. 9, No. 5, May 2011

                                        x 10
                                                                                                                         T=290      K
                                    4                                                                                    T=330      K

  Diffusion Length (m)
                                                                                                                         T=370      K
                           3.5                                                                                           T=400      K






                             0.1                     1           2        3         4          5      6        7        8          9           10
                                                                      Fluence of Radiation (e/cm2)                                      x 10
            Fig. 2. Diffusion Length of irradiated Si PIN photodiode at various radiation fluence and temperature.

                                        x 10
                                                         T=290 K
                                                         T=330 K
                           3.5                           T=370 K
                                                         T=400 K
   Drift Time (s)




                             0.1                     1           2        3         4          5      6        7        8          9           10
                                   Fluence of Radiation                                       x 10         (e/cm2)
       Fig. 3. Drift Time of irradiated Si PIN photodiode at various radiation fluence and temperature.


            Series Resistance (Ω)



                                         0.1             1        2        3         4         5       6        7       8          9           10
                                                                        Fluence of Radiation (e/cm2)                                   x 10
Fig. 4. Series Resistance of irradiated Si PIN photodiode at various radiation fluence and temperature.

                                                                                                                            ISSN 1947-5500
                                                                                                        (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                        Vol. 9, No. 5, May 2011

                                                               x 10

                                                                          T=290       K

                Diffusion Time (s)
                                                           7              T=330       K
                                                                          T=370       K
                                                       6.5                T=400       K





                                                           0.1          1             2             3        4         5        6         7        8          9            10
                                                                                          Fluence of Radiation (e/cm2)                                             x 10
                Fig. 5. Diffusion Time of irradiated Si PIN photodiode versus radiation fluence and temperature.

                     Square Normalized Rise Time (-)

                                                       2.8                    Model           * Expermental data
                                                       2.6                                                                                                     *






                                                        1                                       *
                                                         0.2              2               4             6         8        10        12        14            16             18
                                                                                                Fluence of Radiation (e/cm2)                                        x 10
     Fig. 6. Square rise time normalized to square rise time of unload Si PIN photodiode as function of radiation fluence.

                                                                                                                                                       T=290       K
                                                   12                                                                                                  T=330       K
                                                                                                                                                       T=370       K
                                                                                                                                                       T=400       K
              SNR (dB)




                                                       0.1            1           2                 3        4         5        6         7        8           9            10
                                                                                          Fluence of Radiation (e/cm2)                                             x 10
   Fig.7. Plot of SNR of irradiated Si PIN photodiode versus radiation fluence and temperature, m=0.3, Fn=3 dB, RL=50 Ω.

i) As shown in Fig. 1 has assured that as fluence of radiation                                                             leads to increase in responsivity of device at constant
    on optoelectronic Si PIN device increases, this results in                                                             fluence of radiation.
    responsivity of device decreases at constant ambient                                                               ii) Fig. 2 has demonstrated that as fluence of radiation on
    temperature. But as ambient temperature increases, this                                                                optoelectronic Si PIN device increases, this results in

                                                                                                                                                       ISSN 1947-5500
                                                         (IJCSIS) International Journal of Computer Science and Information Security,
                                                         Vol. 9, No. 5, May 2011

      diffusion length of carriers decreases at constant ambient        radiation defects. It is found that the degradation of device
      temperature. Moreover as ambient temperature increases,           performance decrease with increasing irradiation temperature.
      this leads to increase in diffusion length of carriers at         This result suggests that creation and recovery of the radiation
      constant fluence of radiation.                                    damage proceeds simultaneously at high temperature degrees.
  iii) As shown in Fig. 3 has indicated that as fluence of
      radiation on optoelectronic Si PIN device increases, this                                REFERENCES
      results in drift time of carriers increases at constant
      ambient temperature. But as ambient temperature                   [1] Yu. K. Akimov, “Silicon Radiation Detectors: Instruments
      increases, this leads to decrease in drift time of carriers at        and Experimental Techniques,” IEEE Trans. on Nucl. Sci.,
      constant fluence of radiation.                                        Vol. 50, No. 1, pp. 1–28, 2007.
  iv) Fig. 4 has proved that as fluence of radiation on                 [2] J.R. Srour, C. J. Marshall and P.W. Marshall, “Review of
      optoelectronic Si PIN device increases, this results in               Displacement Damage Effects in Silicon Devices,” IEEE
      series resistance increases at constant ambient                       Trans. on Nucl. Sci., Vol. 50, No. 3, pp. 653-670, 2003.
      temperature. But as ambient temperature increases, this           [3] A.M. Saad, “Effect of cobalt 60 and 1 MeV electron
      leads to decrease in series resistance at constant fluence            irradiation on silicon photodiodes/solar cells,” J. Phys. Vol.
      of radiation.                                                         80, pp.1591–1599, 2002.
  v) As shown in Fig. 5 has indicated that as fluence of                [4] M. Pattabi, S. Krishnan, and G. Sanjeev, “Studies on the
      radiation on optoelectronic Si PIN device increases, this             temperature dependence of I–V and C–V characteristics of
      results in diffusion time of carriers slightly increases at           electron irradiated silicon photo-detectors,” J. Solar Energy
      constant ambient temperature. But as ambient                          Materials & Solar Cells 91, pp.1521–1524, 2007.
      temperature increases, this leads to decrease in diffusion        [5] S. Krishnan, G. Sanjeev, and M. Pattabi, “8 MeV electron
      time of carriers at constant fluence of radiation.                    irradiation effects in silicon photo-detectors,” Nucl. Instr.
  vi) Fig. 6 is confirmed that square of normalized rise time               and Meth. in Physics Research B 264, pp. 79–82, 2007.
      follow the empirical data [10] with the our model.                [6] A. Simon, G. Kalinka, M. Jaks, Z. Pastuovic, M. Nova and
  vii) Fig. 7 has assured that as fluence of radiation on                   A.Z. Kiss, “Investigation of radiation damage in a Si PIN
      optoelectronic Si PIN device increases, this results in               photodiode for particle detector,” Nucl. Instr. and Meth. in
      signal to noise ratio decreases at constant ambient                   Physics Research B 260, pp. 304–308, 2007.
      temperature. Moreover as ambient temperature increases,           [7] M. Van Uffelen, Ivan Genchev and F. Berghmans,
      this leads to decrease in signal to noise ratio at constant           “Reliability study of photodiodes for their potential use in
      fluence of radiation.                                                 future fusion reactor environments,” SPIE Proceeding 5465,
Therefore we can summarized the following results on the SI                 pp. 92-102, 2004.
PIN photodiode performance in the following points:                     [8] K. Gill, S. Dris, R. Grabit, R. Macias, E. Noah, J. Troska
   a) The damage caused by fluence γ results in decreasing                  and F. Vasey, “Radiation hardness assurance and reliability
      responsivity and signal to noise ratio whatever the set of            testing of InGaAs photodiodes for optical control links in
      effect ambient temperature T. But the annealing caused                the CMS experiment,” IEEE Trans. On Nucl. Sci., Vol. 5,
      by ambient temperature T, decrease slightly the negative              No. 2, pp. 1480-1487, 2005.
      effects of irradiation on optoelectronic device                   [9] M. McPherson, “Infrared photoconduction in radiation-
      performance.                                                          damaged silicon diodes,” J. Opt. A: Pure Appl. Opt. 7, pp.
   b) There is a delay in speed of the response as a result of              S325–S330, 2005.
      increasing of the drift and the diffusion times with the          [10] Shinobu Onoda, Toshio Hirao, Hisayoshi Itoh and
      increase of the irradiation fluence.                                  Tsuyoshi Okamoto, “Evaluation of Transient Current in Si
  c) There is an increase in the series resistance Rs of the                PIN photodiode Induced by High-Energy Charged
      device with the irradiation fluence.                                  Particles,” Proc. Sch. Eng. Sch. Inf. Sci. Tokai Univ. 31, pp.
   d) Radiation defect centers will reduce the minority carrier             1-4, 2006.
      diffusion length in undepleted region, then the                   [11] G. Keiser, Optical Fiber Communications, 4th Ed., Tata
      photocurrent will reduce.                                             McGraw-Hill, New Delhi, 2008.
                                                                        [12] M.A. Cappelletti1, U. Urcola1 and E.L. Peltzer y Blanc´a.,
                                                                            “Radiation-damaged simulation PIN photodiodes,”
                       V. Conclusions                                       Semicond. Sci. Technol., Vol. 21, pp. 346–351, 2006.
     In a summary, we have presented analytical modeling of             [13] S. Onoda, T. Hirao, J.S. Laird, H. Mori, T. Okamoto, Y.
the dynamic characteristics of Si PIN photodiode under high                 Koizumi, and H. Itoh, “Spectral Response of a Gamma and
temperature gamma radiation. The modeling basics yields an                  Electron Irradiated Pin Photodiode,” IEEE Trans. on Nucl.
analytical expression for the responsivity of optoelectronic                Sci., Vol. 49, No. 3, pp. 1446-1449, 2002.
device as a function of irradiation Fluence and temperature. It         [14] B. Danilchenko, A. Budnyk, L. Shpinar, D. Poplavskyy,
is evident that also enable better prediction of photocurrent               S.E. Zelensky, K.W.J. Barnham and N.J. Ekins, “1 MeV
levels, delays and signal bandwidth. Moreover we have                       electron irradiation influence on GaAs solar cell
demonstrated the circuit effects on signal performance that                 performance,” J. Solar Energy Materials and Solar Cells 92,
included as a value of signal to noise ratio. The degradation               pp. 1336– 1340, 2008.
and delays can be explained by a decrease in the life time and          [15] H. Ohyama, K. Takakura, K. Hayama, S. Kuboyama, Y.
diffusion length of minority carrier caused by the formation of             Deguchi, and S. Matsuda, E. Simoen and C. Claeys,

                                                                                                      ISSN 1947-5500
                                                    (IJCSIS) International Journal of Computer Science and Information Security,
                                                    Vol. 9, No. 5, May 2011

   “Damage coefficient in high-temperature particle and γ-         Author's profile
   irradiated silicon p–i–n diodes,” J. Appl. Phys. Lett., Vol.                         Dr. Ahmed Nabih Zaki Rashed
   82, No. 2, pp. 296-298, 2003.                                                        was born in Menouf city, Menoufia State,
[16] M. A. Cappelletti, A.P. C´edola1 and E.L. Peltzer y.                               Egypt country in 23 July, 1976. Received the
   Blanc´a, “Simulation of silicon PIN photodiodes for use in                           B.Sc., M.Sc., and Ph.D. scientific degrees in the
                                                                                        Electronics and Electrical Communications
   space-radiation environments,” Semicond. Sci. Technol.,                              Engineering Department from Faculty of
   Vol. 23, No. 2, pp. 7-13, 2008.                                                      Electronic Engineering, Menoufia University
[17] J.R. Srour, Fellow and D.H. Lo, “Universal Damage Factor                           in 1999, 2005, and 2010 respectively.
   for Radiation-Induced Dark Current in Silicon Devices,”                              Currently, his job carrier is a scientific lecturer
   IEEE Trans. on Nucl. Sci., Vol. 47, No. 6, pp. 2451-2459,                            in Electronics and Electrical Communications
   2000.                                                                                Engineering Department, Faculty of Electronic
[18] K. Takakura, K. Hayama, D. Watanabe, H. Ohyama, T.                                 Engineering, Menoufia university, Menouf,
   Kudou, K. Shigaki, S. Matsuda, S. Kuboyama, T.                                       postal Menouf city code: 32951, EGYPT.
   Kishikawa, J. Uemura, E. Simoen and C. Claeys,                  His scientific master science thesis has focused on polymer fibers
                                                                   in optical access communication systems. Moreover his scientific
   “Radiation defects and degradation of Si photodiodes            Ph. D. thesis has focused on recent applications in linear or
   irradiated by neutrons at low temperature,” Physica B 376–      nonlinear passive or active in optical networks. His interesting
   377, pp. 403–406, 2006.                                         research mainly focuses on transmission capacity, a data rate
[19] H. Ohyama, T. Hirao, E. Simoen, C. Claeys, S. Onoda, Y.       product and long transmission distances of passive and active
   Takami and H. Itoh, “Impact of lattice defects on the           optical communication networks, wireless communication, radio
   performance degradation of Si photodiodes by high-              over fiber communication systems, and optical network security
   temperature gamma and electron Irradiation,” Physica B          and management. He has published many high scientific research
   308–310, pp. 1226–1229, 2001.                                   papers in high quality and technical international journals in the
                                                                   field of advanced communication systems, optoelectronic devices,
[20] H. Ohyama, E. Simoen, C. Claeys, K. Takakura, H.
                                                                   and passive optical access communication networks. His areas of
   Matsuoka, T. Jono, J. Uemura and T. Kishikawa,                  interest and experience in optical communication systems,
   “Radiation damage in Si photodiodes by high-temperature         advanced optical communication networks, wireless optical access
   Irradiation,” Physica E 16, pp. 533 – 538, 2003.                networks, analog communication systems, optical filters and
[21] S. M. Sze, Physics of Semiconductor Devices, John Wiley       Sensors, digital communication systems, optoelectronics devices,
   & Sons, 3rd Ed, USA, 2007.                                      and advanced material science, network management systems,
[22] H. Li, “Refractive Index of Silicon and Germanium and Its     multimedia data base, network security, encryption and optical
   Wavelength and Temperature Derivatives, Journal of              access computing systems. He is a reviewer member in high quality
   Physical and Chemical Reference Data,” Vol. 9, No. 3, pp.       scientific research international journals in the field of Electronics,
                                                                   Electrical communication and advanced optical communication
   561−658, 1980.
                                                                   systems and communication access networks. His personal
[23] J. Tauc, Amorphous and liquid semiconductors, New             electronic mail (
   York, Plenum Press, 1974.
[24] Benjawan Kjornrattanawanich, Raj Korde, Craig N. Boyer,
   Glenn E. Holland, and John F. Seely, “Temperature
   Dependence of the EUV Responsivity of Silicon
   Photodiode Detectors,” IEEE Trans. on Electron Devices,
   Vol. 53, No. 2, pp.218-223, 2006.
[25] Y. Pan, F. Inam, M. Zhang, and D. A. Drabold, “Atomistic
   Origin of Urbach Tails in Amorphous Silicon,” J. Physical
   Review Letters, Vol. 20, No. 6, pp. 1-4, 2008.
[26] Martin A. Green, “Self-consistent optical parameters of
   intrinsic silicon at 300 K including temperature
   coefficients,” J. Solar Energy Materials & Solar Cells 92,
   pp. 1305– 1310, 2008.
[27] K. Konno, O. Matsushima, D. Navarro, and M. Miura-
   Mattausch, “High frequency response of p-i-n photodiodes
   analyzed by an analytical model in Fourier space,” J. Appl.
   Phys., Vol. 96, No. 7, pp. 3839-3844, 2004.

                                                                                                    ISSN 1947-5500