Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID)
The effect of photons trapped at the LED side due to total internal reflection on the transient behavior of an Optoelectronic Integrated Device (OEID) is considered in this paper. The device is composed of a Heterojunction Phototransistor (HPT) and a Light Emitting Diode (LED). The expressions de...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2009
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| Цитувати: | Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) / Sh.M. Eladl // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 255-259. — Бібліогр.: 11 назв. — англ. |
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irk-123456789-1188702017-06-01T03:04:25Z Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) Eladl, Sh.M. The effect of photons trapped at the LED side due to total internal reflection on the transient behavior of an Optoelectronic Integrated Device (OEID) is considered in this paper. The device is composed of a Heterojunction Phototransistor (HPT) and a Light Emitting Diode (LED). The expressions describing the transient response of the output photons flux, the rise time, and the output derivative are derived. The effect of the various device parameters on the transient response is outlined. The results show that the transient response of these types of devices is strongly dependent on the ratio of these trapped photons in the LED part. Also the device under consideration can be changed from switching mode to the amplification mode, if the fractions of trapped photons exceed a specified value. This type of the model can be exploited as an optical amplifier, optical switching device and other applications. 2009 Article Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) / Sh.M. Eladl // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 255-259. — Бібліогр.: 11 назв. — англ. 1560-8034 PACS 85.60.-q, Dw, Jb http://dspace.nbuv.gov.ua/handle/123456789/118870 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The effect of photons trapped at the LED side due to total internal reflection
on the transient behavior of an Optoelectronic Integrated Device (OEID) is considered in
this paper. The device is composed of a Heterojunction Phototransistor (HPT) and a
Light Emitting Diode (LED). The expressions describing the transient response of the
output photons flux, the rise time, and the output derivative are derived. The effect of the
various device parameters on the transient response is outlined. The results show that the
transient response of these types of devices is strongly dependent on the ratio of these
trapped photons in the LED part. Also the device under consideration can be changed
from switching mode to the amplification mode, if the fractions of trapped photons
exceed a specified value. This type of the model can be exploited as an optical amplifier,
optical switching device and other applications. |
| format |
Article |
| author |
Eladl, Sh.M. |
| spellingShingle |
Eladl, Sh.M. Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Eladl, Sh.M. |
| author_sort |
Eladl, Sh.M. |
| title |
Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) |
| title_short |
Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) |
| title_full |
Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) |
| title_fullStr |
Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) |
| title_full_unstemmed |
Modeling of photons trapping effect on the performance of HPT-LED Optoelectronic Integrated Device (OEID) |
| title_sort |
modeling of photons trapping effect on the performance of hpt-led optoelectronic integrated device (oeid) |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2009 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118870 |
| citation_txt |
Modeling of photons trapping effect on the performance
of HPT-LED Optoelectronic Integrated Device (OEID) / Sh.M. Eladl // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 255-259. — Бібліогр.: 11 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT eladlshm modelingofphotonstrappingeffectontheperformanceofhptledoptoelectronicintegrateddeviceoeid |
| first_indexed |
2025-07-08T14:48:47Z |
| last_indexed |
2025-07-08T14:48:47Z |
| _version_ |
1837090605889486848 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 255-259.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
255
PACS 85.60.-q, Dw, Jb
Modeling of photons trapping effect on the performance
of HPT-LED Optoelectronic Integrated Device (OEID)
Sh.M. Eladl
Rad. Eng. Dept., NCRRT, P.O. Box 29, Nasr City, Atomic Energy Authority, Egypt
E-mail: Shaban_45@yahoo.com
Abstract. The effect of photons trapped at the LED side due to total internal reflection
on the transient behavior of an Optoelectronic Integrated Device (OEID) is considered in
this paper. The device is composed of a Heterojunction Phototransistor (HPT) and a
Light Emitting Diode (LED). The expressions describing the transient response of the
output photons flux, the rise time, and the output derivative are derived. The effect of the
various device parameters on the transient response is outlined. The results show that the
transient response of these types of devices is strongly dependent on the ratio of these
trapped photons in the LED part. Also the device under consideration can be changed
from switching mode to the amplification mode, if the fractions of trapped photons
exceed a specified value. This type of the model can be exploited as an optical amplifier,
optical switching device and other applications.
Keywords: optoelectronic integrated device, heterojunction phototransistor, light
emitting diode.
Manuscript received 08.02.09; revised manuscript received 05.04.09; accepted for
publication 14.05.09; published online 15.05.09.
1. Introduction
Optoelectronic Integrated Devices (OEIDs) have
received more attention nowadays due to their potential
applications in various areas, such as optical
amplifications, switching, and communications [1-5].
This type of devices is still demanded for the evolution
of optical communication and optical signal processing
because the detecting part possesses the feature of a
transistor in most cases. One or more OEIDs can
function as bistable optical switches, optical inverters,
AND, NAND, and NOR gates. Other structure is
suitable for RCE [7], making these devices ideal for
WDM optical interconnects. One type of OEIDs consists
of a Heterojunction Phototransistor (HPT) that is
vertically integrated with a Light Emitting Diode (LED).
The input light illuminates the phototransistor, and it is
converted into photoexcited carriers that leave the HPT
part and are injected into the LED active region. Due to
the wide-gap confinement layers, most of these carriers
recombine there leading to the emission of an intensified
light from the LED side. Fraction of this emitted light is
trapped in the LED will be reabsorbed by the carriers in
the LED active layer.
A stability testing of a new version of OEIDs was
developed in [8]. The testing demonstrates that its
optical gain is stable as long as the value of the optical
feedback is maintained below the threshold value, while
exhibits instability for values of optical feedback, which
are greater or equal to this threshold value. Recently, this
type of structure has been exploited for optical
upconversion devices that convert input 1.5 µm light to
output 0.87 µm light with a built-in gain mechanism [9].
Incoming 1.5 μm optical radiation is absorbed by the
HPT, generating an amplified photocurrent. The
resultant photocurrent drives the LED that emits at
0.87 μm, which could be detected by a conventional
silicon charge-coupled device.
More recently [10], a numerical analysis for
dynamic response of a coupled periodic multi-quantum
wells heterojunction phototransistor (CP-MQW HPT)
integrated over a strained quantum well laser diode was
developed. It was observed that the possibility of
operation of the developed device in amplification and
switching modes was also available as similar to
conventional types. In this paper, a detailed investigation
of the transient behavior of OEID is presented taking
into account the photon mechanism resulted from the
trapped photons at the LED side due to total internal
reflection process.
The device characteristics under ionizing irradiation
are investigated based on the equivalent circuit of the
constituent devices and the optical feedback inside the
device by Ref. [11]. The switching voltage of this type
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 255-259.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
256
device was increased with the ionizing radiation. The
purpose of the current paper is to use a simple method to
analyze the transient characteristics of optoelectronic
integrated devices, the effect of the photons trapping at the
LED side due to internal reflection on the transient
behavior of these devices is taken into consideration. The
paper is organized as follows: formulation of the specified
parameters that describe the transient response, derivative,
and rise time of OEID is presented in Section 2. The
generated curves resulting are outlined and discussed in
Section 3. Finally, conclusion of the work is discussed in
Section 4.
2. Theoretical analysis
The block diagram of the considered optoelectronic
integrated device with optical feedback is shown in
Fig. 1a. The output photon flux can be expressed as
.
1
1
int
int
out
q
JT
(1)
Where J is the excited photocurrent inside the
OEID and has two components, namely: the first one is
due to the direct light incident on HPT from the external
source, the second one is due to the light back inside the
device from the LED to HPT, δ represents the ratio of
photons that trapped within the LED active region due to
the internal reflection at the LED interface, T is the
transmission coefficient at the LED interface, q is the
electric charge, while int is the LED internal quantum
efficiency.
The excited photocurrent density inside the device,
if the optical feedback is considered, can be expressed
as [3]:
gk
gq
J
1
)(in , (2)
where g(ω) and η(ω) denote the frequency response of
the optical conversion gain of HPT and the external
quantum efficiency of the LED, respectively, and k(ω),
the ratio of the photons which reach the HPT to those
emitted by the LED that is called as optical feedback and
assumed to be constant, k(ω) = k. This optical feedback
is assumed to be positive one, because it is added to the
main input light with no phase changing due to the small
time delay concerning it compared with the forward path
time delay.
)(in g
)(k
)(out
J
Fig. 1a. Block diagram of OEID with optical feedback.
Using Eqs (1) and (2), the formula for the
frequency response of the output photon flux can be
expressed as:
int
inint
int
out 1
)(
)(1
1
gk
gT
. (3)
When the input light is assumed as a step function
in time, the Laplace transform of the photon flux in the
case of no optical feedback (k = 0) can be obtained as
.
1/111
)1(
)(
1
0int
1
0int0
in
out
sss
s
gT
s
(4)
Where g0 = β0ηh0 denotes the conversion gain of
the HPT in the low frequency regime, and β0 and ηh0 are
the current gain and the quantum efficiency of the HPT
in the low frequency regime, and ωβ is the beta cut-off
frequency. ω1 is the cut-off frequency of the LED where
0
1
1 is the minority carrier lifetime.
The time response of
in
out
for the optoelectronic
integrated devices can be obtained from the inverse
Laplace of Eq. (4) as
.
1/111
)1(
)(
1
0int
1
0int0
in
out 1
sss
s
gT
Lt
(5)
Thus, the time response of
in
out
can be obtained as:
.
)(1
1
1
1
1
1)(
)1(
10int10int1
10int10int1
100int
in
out
0int1
t
t
e
e
gTt
(6)
If ω1 >> ωβ, the above equation can be reduced to
the following form
t
e
gT
t 1
1
1
)(
0int
00int
in
out . (7)
The derivative of
in
out
for the OEID with respect
to time is expressed by
.
1
)(
)(
1
)(
)1(
0int1
10int1
10int1
100int
in
out
0int1
tt ee
gT
t
dt
d
(8)
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 255-259.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
257
The above expression describes how fast the output
photons change with time. Using the approximation
ω1 >> ωβ will yield to
te
gT
t
dt
d
)1(
1
)(
0int
00int
in
out . (9)
The rise time of
in
out
for optoelectronic integrated
devices is defined as the time required for )(
in
out t
to
rise to 0.9 of its final value, by solving Eq. (6). The rise
time can be given as
0int
00int
0int
00int
1
1
9.0
1
1
ln
1
gT
gT
T
a
A . (10)
When
0int
00int
1
1
gT
a , then
3.2
AT . (11)
If the optical feedback inside the device is
considered, the following equation will be valid:
,
)1(
)( 0int0
in
out
sZ
gT
s
(12)
where
.
11
1
1
111
1
0int0
1
0int
1
ss
kg
s
ss
ssZ
(13)
Using the approximation ω1 >> ωβ will yield to
.1
111
11
)(
0int
00int
1
1
1
2
0int00int
100int0int
in
out
t
gk
e
gk
gT
t
(14)
The derivative of the output photon flux emerging
from OEID with respect to time is expressed by
.
11)1(
1
)(
00int11
00int0int
00int
in
out
tgk
e
gk
gT
t
dt
d
(15)
The rise time of the output photon flux, where the
optical feedback is taken into consideration, can be
expressed as:
R
gk
TA ln
11
1
00int0int
0int
. (16)
Here
,
1
119.01
00int
00int0int00int
gT
gkgT
R a
(17)
where a is the steady state output photon flux
00int0int
00int
111
1
gk
gT
a
. (18)
Then,
00int0int
0int
11
13.2
gk
TA
. (19)
3. Results and discussion
The device parameters used in the subsequent calculated
figures are the same as those used by Zhu et al. [6],
where ωβ = 108 Hz, ω1 = 1010 Hz, T = 0.7, δ = 0.5, and
ηint 0g0 = 100. The input light flux in is assumed to be a
step function in time. A complete schematic picture of
the proposed OEID is shown in Fig. 1b. Since the same
InGaAs active region is used for both HPT and LED,
some portion of the same spectral generated light at the
LED side traverses back through the cladd and collector
regions to be absorbed again at the HPT InGaAs active
region causing an optical feedback. The thickness of the
cladd and collector regions play a significant role on
controlling the magnitude of this optical feedback, the
amplitude of the optical feedback is inversely
proportional to the thickness of these two regions, while
it is directly proportional to the thickness of the two
active regions. The type of materials of the active
regions has the major effect on the properties of the
spectral response for the generated light. The transient
response of inout of the OEID in the amplification
mode is shown in Fig. 2. It can be seen that inout of
the device approaches a definite value, this definite
value depends on the optical conversion gain of the
HPT, external quantum efficiency of the light emitting
diode, the value of the optical feedback within the
device, and the value of the trapping factor at the LED
side. The value of external quantum efficiency of the
LED is much lower than the internal one due to
reabsorption and total internal reflection within the LED
active region. In order to prevent reabsorption, the layer
above the active region has to be with higher band gap
than that of the active region to ensure good confinement
of photons inside this layer. Also, the device operates in
a stable mode called the amplification mode.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 255-259.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
258
dt
d
in
out
Fig. 3. Derivative of output photon flux with time at
different δ values.
inout
0β
0β
0β
Fig. 4. Dependence of inout on the trapping factor at
different β0 values.
HPT
LED
InP Emitter
InGaAs Base
InGaAs Collector
InP Cladding
InGaAs Active
InP Cladding
Input Light
Output Light
Fig. 1b. Schematic view of the proposed OEID.
V Bias
Fig. 1b. Schematic view of the proposed OEID.
inout
Fig. 2. Amplification mode transient response of inout
versus time at different δ values.
Fig. 3 plots )(
in
out t
dt
d
versus time at different
values of δ, where the value of this derivative is used to
measure the speed of photon flux growth that emerges
from the device. The plot exhibits a pronounced
maximum value at a certain time, and after that it decays
exponentially to a minimum value where the output flux
reaches its final value. At any time below this specified
value, the derivative increases with time, while the
derivative decreases with time above this specified value
of time. If the optical feedback within the device is
increased, the obtained inout will increase, while this
specified value will not be affected or changed by the
increase in optical feedback.
Fig. 4 illustrates the decrease in inout with
increasing δ. Such decrease is more pronounced in
LEDs with a small quantum efficiency in which the
output photon flux is smaller. The HPT conversion gain
play a major role in obtaining a higher inout value,
where the higher optical conversion gain of HPT means
higher current density injected to the LED part and,
hence, a higher inout value. Fig. 5 shows the time
dependence of inout at different values of δ. This
operation mode is the so-called switching mode where
inout is increased linearly and exhibits an abrupt
change from low current state to high current state,
which agree with the switching characteristics. From
the figure, the values of δ limit the switching speed
where the device with lower δ switches earlier than that
of higher δ. Faster and higher performance OEID can
be achieved using the LED with lower trapping factor.
Since δ represents the fraction of photons propagating
outside the critical angle cone of the LED, so it is
necessary to decrease its value to ensure maximum
output flux of photons through the LED active region.
III-V materials have small critical angle cone, therefore
the radiation emitted suffers from total internal
reflection. To decrease the value of δ, the refractive
index of the LED active region has to be chosen with a
small value.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 255-259.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
259
t
inout
Fig. 5. Switching mode transient response of inout versus
time at different δ values.
Fig. 6. Rise time versus δ at different values of optical
feedback k.
The dependence of the rise time of inout of
OEID on the optical feedback coefficient in the
amplification mode is shown in Fig. 6. It is clear that by
increasing the optical feedback, there is an increase in
the rise time due to the increase of the difference
between inout in the initial and the final state. The
optical feedback is usually weakened in the
amplification mode by inserting an absorption layer
between the HPT and LED, and thus the rise time in this
mode is equal in magnitude as that of the HPT with
optical feedback.
4. Conclusions
A theoretical model including the effect of photons
trapped in the LED side due to total internal reflection
on behavior of an Optoelectronic Integrated Device was
proposed and used to evaluate its characteristics.
Analytical formulas for the transient response,
derivative, and rise time were derived. The results show
that photon trapping within the LED region strongly
influences the device gain and switching speed. Optical
feedback influences crucially functions and operation
modes where the lower values of optical feedback allow
the device to operate in amplification mode, while the
higher values to operate in the switching mode. The
obtained expressions can be used for the optimization of
the device performance.
References
1. S.A. Feld, F.R. Beyette, Jr., M.J. Hafich, H.Y. Lee,
G.Y. Robinson, and C.W. Wilmsen, Electrical and
optical feedback in an InGaAs/InP Light
Amplifying Optical Switch (LAOS) // IEEE Trans.
Electron Device 38, No. 11, p. 2452-2458 (1991).
2. A. Vahid, S. Noda, A. Sasaki, Analysis for relative
intensity noise of optoelectronic integrated device
by heterojunction phototransistor and laser diode //
Solid State Electron. 41, p. 465-471 (1997).
3. Susumu Noda, Toru Takayama, Kimitaka Shibata,
and Akio Sasaki, High gain and very sensitive
photonic switching device by integration of
heterojunction and laser diode // IEEE Trans.
Electron Devices 39, No. 2, p. 309-311 (1992).
4. S. Noda, K. Yasuhiro, and A. Sasaki,
Optoelectronic integrated tristable device with
optically controlled set and reset functions // J.
Quantum Electron. 31, No. 8, p. 1465-1473 (1995).
5. Satyabrata Jit and B.B. Paul, A new Optoelectronic
Integrated Device for Light Amplifying Optical
Switch (LAOS) // IEEE Trans. Electron Devices
48, No. 12, p. 2732-2739 (2001).
6. Yu Zhu, Susumu Noda, and Akio Sasaki,
Theoretical analysis of transient behavior of
optoelectronic integrated devices // IEEE Trans.
Electron Devices 42, No. 4, p. 646-648 (1995).
7. M.S. Unlü, S. Strite, A. Salvador, A.L. Demirel,
and H. Morkoc, Wavelength discriminating optical
switch // IEEE Photon. Tech. Lett. 3, No. 12,
p. 1126-1129 (1991).
8. M.B. El_Mashade, M. Ashry, Sh.M. Eladl, M.S.
Rageh, Performance analysis and stability testing
of a new structure of optoelectronic integrated
device // Microelectron. J. 35, No. 7, p. 585-589
(2004).
9. H. Luo, D. Ban, H.C. Liu et al., Optical
upconverter with integrated heterojunction
phototransistor and light-emitting diode // Appl.
Phys. Lett. 88, 073501 (2006).
10. E. Darabi, V. Ahmadi, and K. Mirabbaszadeh,
Numerical analysis of an optoelectronic integrated
device composed of coupled periodic MQW
phototransistor and strained-QW laser diode //
Solid-State Electron. 50, No. 3, p. 473-479 (2006).
11. Sh.M. Eladl, Modeling of ionizing radiation effect
on optoelectronic-integrated devices (OEIDs) //
Microelectron. J. 40, No. 1, p. 193-196 (2009).
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