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IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 2, FEBRUARY 2013
On the Efficiency Decrease of the GaN
Light-Emitting Nanorod Arrays
Liang-Yi Chen, Chi-Kang Li, Jin-Yi Tan, Li-Chuan Huang, Yuh-Renn Wu, Member, IEEE,
and Jian Jang Huang, Senior Member, IEEE
Abstract— Nanostructure light emitting arrays, with the mitigated quantum confined stark effect, provide a different angle
to investigate the efficiency decrease in the GaN based LEDs.
In this paper, the external quantum efficiency and the electroluminescent spectra of GaN based nanorod LEDs are characterized through experiments and simulations. The strains in
the InGaN/GaNnanorods are varied with the choice of nanorod
sidewall passivation materials. Our results indicate that Auger
recombination dominates at low-level currents. However, even
though the effect of Auger accounts fora higher percentage
weighting, the increase number of leakage carriers out of quantum wells is responsible for the efficiency drop at high current
levels.
Index Terms— Light-emitting diodes, nanofabrication and
quantum wells, nanostructures.
I. I NTRODUCTION
R
ECENTLY, GaN based nanorod light emitting diodes
(LEDs) have been widely explored [1]–[4] due to the
unique properties of nanostructures, such as the relaxed strain
in the InGaN/GaN multiple quantum wells(MQWs) and the
improved light extraction as most of the generated photons
fall within the escape cone along nanorods. The nanostructureLEDs have the potential for next-generation general lighting.
In the past, we have demonstrated GaN nanorod LEDs with
6807mW/cm2 optical output at 32A/cm2 and the reverse
current in the nA scale [5]. Furthermore, we discovered that
strain in the nanorod structure is affected by the passivation
materials, such as the spin-on-glass (SOG) or the PECVD
(plasma enhanced chemical vapor deposition) grown SiO2 , for
filling up the nanorod spacing [6]. The strain in the MQWs
tilts the energy band and results in various amounts of peak
wavelength shifts in the EL(electroluminescent) spectra with
the injection currents. The k•p method and the piezoelectric
field were both applied to identify the correlation between the
strain, band tilt and light-emitting wavelength of the nanorod
samples [6]. However, previous work at low injection currents
has neglected both the quantum efficiency and the screening
effect in the quantum well at high carrier injections.
Manuscript received October 2, 2012; revised December 19, 2012; accepted
December 28, 2012. Date of publication January 4, 2013; date of current
version January 18, 2013. This work was supported in part by the National
Science Council in Taiwan, under Grant 100-2628-E-002-030-MY3.
The authors are with the Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan (e-mail:
jjhuang@cc.ee.ntu.edu.tw).
Color versions of one or more of the figures in this paper are available
online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/JQE.2013.2237885
Up to now, the effect of efficiency decrease (or called
droop effect) has not yet thoroughly investigated in GaN based
nanorod LED arrays. In the present work, nanorod LED arrays
at high injection currents are characterized. Nanostructure
lighting emitting arrays, with the mitigated QCSE (quantum
confined stark effect) [7], [8], provide a different angle to
investigate the root cause of efficiency drop in the GaN
based LEDs. As various effects that influence the decrease
of efficiency droop, such as Auger [9], [10], carrier leakage
(or overflow) [11], [12], and junction temperature [13] can’t be
singled out in typical LED structure, we intend to investigate
the EQE (external quantum efficiency) based on the correlation
between the experiment and simulation. In this study, choice
of passivation materials provides various degrees of strain
relaxation (and thus the polarization and carrier leakage) in the
MQWs. And effects of carrier screening, leakage and Auger
recombination are considered in the simulation to investigate
the efficiency decrease.
II. E XPERIMENTS , M EASUREMENTS AND S IMULATIONS
In contrast to the selective-area epitaxy for forming
GaN-based nanorods [14], [15], in this study, dry-etching
method for forming GaN-based nanorod was used. Before the
dry-etching process, the two dimensional (2-D) nano-mask is
used to define the pattern of nanorod structure. Recent works
have reported the fabrication of highly-ordered 2-D patterning
in large-area wafer-scale region by using rapid convective
deposition method of silica micro-/nano-particle monolayer
arrays [16], [17] or diblock-copolymer lithography methods
[18]. The current works focused on the use of spin-coating
method in deposition of the silica colloidal lithography step
for patterning the nanorods LEDs [8].We prepare two types of
InGaN/GaN-based nanorod LED arrays, one is passivated with
PECVD grown SiO2 and the other is with spin-coated SOG.
The PECVD process was performed using SiH4 /Ar (40sccm)
and N2 O (160sccm) as source gases, at the radio frequency
power of 140W under the substrate temperature of 300°. The
Siloxanes family SOG was spin-coated, reflowed at 72° for
15 mins and then baked in the over at 400° for one hour. The
device fabrication is very similar to our previous work [6],
[8], [19] except using the epi-wafers from various MOCVD
(metal-organic chemical vapor deposition) growth runs. The
patterning steps of the nanorods were carried out using spincoated silica colloidal lithography process, as described in [8].
Fig. 1 shows the schematic diagram of the nanorod structure.
0018–9197/05$31.00 © 2013 IEEE
CHEN et al.: EFFICIENCY DECREASE OF THE GaN LIGHT-EMITTING NANOROD ARRAYS
225
(SiO2 or SOG)
Fig. 1. Schematic of the nanorod LED array. The passivation layer is either
spin-coated SOG or PECVD-grown SiO2 .
For convenience, nanorod LEDs passivated with SOG are
denoted as the LED-SOG while nanorods passivated with SiO2
are LED-SiO2 . To extract the strain of the nanorod LED structure, the micro-Raman measurement was conducted using the
laser at the wavelength of 532 nm as the excitation source. As
for the electroluminescence (EL) and Luminescence-current
(L-I) measurements, in order to minimize the effect of junction
heating, pulsed currents were injected with a 1% duty cycle
and a pulse period of 50 ms throughout the experiment.
As for simulation, we employed one-dimension selfconsistent finite element method (FEM) solver [20], [21].
The method solves Poisson and drift–diffusion equations selfconsistently so that the internal quantum efficiency (IQE) and
the optical transition energy can be obtained.
(a)
III. R ESULTS AND D ISCUSSION
A. L-I Measurement and the Introduction of the Simulation
Model
Five devices of each type (LED-SOG and LED-SiO2 ) of
nanorod arrays were employed for L-I measurement. The statistic data are shown in Fig. 2(a) (right axis) with the error bars
labeled. For convenience, the following numerical values of
L-I and EQE are represented by the mean value. At the
injection current of 100mA, the optical power of LED-SOG
is 14.2% higher than that of LED-SiO2 . The optical power
of these two type of devices is influenced by the sidewall
passivation based on the following reasons. First, part of the
photons generated in MQWs are extracted from the sidewalls
and are affected by the refractive index of SiO2 and SOG.
Second, the IQE of the devices is affected by the nanorod
sidewall defects induced during ICP etching. And third, as
suggested by our previous work [6], the choice of passivation
material results in various strains in InGaN/GaN MQWs. For
the first case, the refractive index of SiO2 and SOG is 1.46
and 1.40. If the small difference of the refractive index is the
root-cause, the number of photons that escapes from the active
layers (n = 2.5) to the air through the passivated material of
LED-SiO2 should be higher than that of LED-SOG due to
a larger refractive index, which contradicts our experimental
observations. And in the second case, since the nanorod
formation of both devices were carried out simultaneously,
the sidewall defects picked up during ICP etching should
have the same amount. Also, the reverse current at –5V is
lower than 18nA (see Fig. 2(b)), indicating that the sidewall
defects are effectively suppressed. As a result, the strain may
(b)
Fig. 2. (a) L–I curves (right axis) and the corresponding EQE of nanorod
LEDs (left axis). In this plot, five devices of each type were measured. The
mean values along with the error bars are shown. (b) I–V curves of LED-SOG
(black line) and LED-SiO2 (red line).
play a key role in the light output behaviors and will be
scrutinized latter in this work. Furthermore, we also plot the
external quantum efficiency (EQE), defined as the measured
output power divided by the injection current, in the left
axis of Fig. 2(a) by normalizing the maximum efficiency of
LED-SOG to 1. The EQE curves show the droop effect of
both devices. And the difference of maximum EQE between
two devices is 6.16%. As suggested by our previous work
[6], the passivation layer of either SOG or SiO2 contributes
to different degree of strain relaxation in the InGaN/GaN
nanorod MQWs and results in various piezoelectric fields. The
quantum well band profiles and the carrier distribution are thus
affected. To further study the EQE behaviors with injection
currents/carriers, numerical simulation was next conducted.
The internal quantum efficiency (IQE) is defined by the
following equation.
(1)
IQE = Irad Itotal
(2)
Itotal = ISRH + Irad + IAug + Ileak
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IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 2, FEBRUARY 2013
TABLE I
PARAMETERS E MPLOYED IN THE S IMULATION
Thickness (nm)
[30]
μe
electron
mobility (cm2 /Vs)
[30]
μh
hole
mobility (cm2 /Vs)
Doping density
(1/cm3 )
Activation
energy (meV)
LED-SOG
carrier nonradiative
lifetimesτ [23] (s)
n-Gan
i-InGaN
i-GaN
p-GaN
2000
3
14
160
200
300
200
200
10
10
10
5
5.00E+18 1.00E+15 1.00E+15 3.00E+19
25
25
25
170
2.172E-08 2.172E-08 2.172E-08 2.172E-08
(a)
LED-SiO2
carrier nonradiative
lifetimesτ [23] (s)
1.812E-08 1.812E-08 1.812E-08 1.812E-08
Radiative
recombination
coefficient B[22]
1.00E-11
1.00E-11
1.00E-11
1.00E-11
Auger recombination
coefficient C[24]
2.00E-31
2.00E-31
2.00E-31
2.00E-31
Where Irad = Bnp is the radiative recombination current
(n and p are the free electron and hole carrier density
respectively, and B is the radiative recombination coefficient)
[22], ISRH is the Shockley–Read–Hall recombination current
and is defined in [23]. Furthermore, IAug = C(n2 p + p2 n)
is the current contributed from the Auger recombination,
in which C is the Auger coefficient [24]. And Ileak is the
current contributed from the carrier leakage, of which is
mainly attributed to the following two reasons. First of all,
the polarization induced energy band tilt leads to the escape
of electrons out of the quantum wells. And second, since
the mobility and carrier density of holes are much lower
than electrons, there is spatial imbalance of electron and
hole current across the quantum well region. The above two
phenomena become more obvious at high injection current
density when electrons fill up the energy states of quantum
wells. Thus, the leakage current leads to reduction in current
injection efficiency [25], [26], which will be severely quenched
at high current density. Recent works have shown the importance of considering the current injection efficiency in InGaNbased LEDs [25], which is consistent with the general physics
of current injection efficiency in quantum well lasers/LEDs
[26]. Moreover, the overflow current may recombine in the
p-GaN or mostly surface recombine in the p-type contact.
The simulated carrier leakage considers the band profile by
first obtaining the piezoelectric field Epz in the quantum well
and then by solving the 1-dimension (1-D) FEM Poisson and
drift–diffusion equations. Note that the strain in the nanorods
was assumed as uniform in biaxial directions, however there
exists spatial 2-D/3-D strain distribution within the nanorods
from the ICP etching and passivation methods. The current
(b)
Fig. 3.
(a) Micro-Raman measurement of InGaN/GaN nanorod LEDs.
(b) Close-up view of InGaN E2H phonon mode shoulder around the wavenumber of 560 cm−1 .
distribution of the entire device can thus be obtained. We
then sum the current which escapes from the quantum well
and divided by the injection current to be the overflow ratio,
Ileak /Itotal [22]. Ileak can thus be determined.
At the steady state, carriers fallen out of the MQWs are
considered as the leakage current while those in the quantum
wells are applied to the model using A, B and C coefficients
of which the IQE, ηIQE , is expressed as
ηIQE =
Irad
Irad
=
.
ISRH + Irad + IAug + Ileak
Itotal
(3)
The detailed parameters of the simulation are listed in
Table I.
In order to calculate the IQE of the devices with straininduced piezoelectric field, micro-Raman spectroscopy was
conducted on both LED-SOG and LED-SiO2 . The results are
shown in Fig. 3(a). The main peak near 570cm−1 is the E2H
mode of GaN while the shoulder near 560cm−1 is the InGaN
E2H mode correlated to the biaxial strain of InGaN quantum
CHEN et al.: EFFICIENCY DECREASE OF THE GaN LIGHT-EMITTING NANOROD ARRAYS
(a)
(b)
Fig. 4. (a) Simulated IQEs by setting the Auger coefficient C = 0 and
C = 2 × 10−31 cm6 s−1 on both devices. In the calculation, the strain
obtained in Fig. 3 is considered. (b) Comparisons of the simulation with
the experimental work. The results indicate that the effect of Auger has to be
considered in order to correlate the simulation with the measurement.
wells. The Lorentzian curves are applied for curve fitting and
peaks of the InGaN E2H phonon mode are labeled by black
arrows in close-up views of Fig. 3(b). The peak positions of
LED-SiO2 and LED-SOG are 562.09 cm−1 and 561.23 cm−1
respectively. In our previous work [6], we developed a series
of calculation that transforms the wavenumber shift of the
Raman spectrum into the piezoelectric field within the InGaN
layer. From Fig. 3(b), the strain is calculated to be −1.67%
and −1.53% for LED-SiO2 and LED-SOG, respectively. As
the strain in the MQWs of LED-SOG is more relaxed than
that of LED-SiO2 , the LED-SOG possesses less piezoelectric
field and flatter band profile, which increases the probability
of electron-hole overlap in the quantum wells. Other methods
for suppressing the charge separation issue in InGaN QW
LEDs [27] had also been reported by using non-/semi-polar
QW [28], polar QW with large overlap designs [27], and
227
Fig. 5.
Percentage weightings of the carrier leakage out of MQWs
(Ileak /Itotal , left axis) and of the Auger recombination (IAug /Itotal , right axis)
of both LED-SOG and LED-SiO2 .
ternary substrate/template for strain mismatch reduction [29].
The optical output power of LED-SOG is thus higher than that
of LED-SiO2 . In the following calculation, the strain obtained
from the Raman spectra will be employed.
To reconciliate experimental observations with theoretical
predictions, the effect of Auger is first neglected by setting
C = 0. From Fig. 4(a), the simulated IQE (C = 0) finds
its maximum at a larger current than the experimental ones
and then gradually decreases. On the other hand, with the
Auger coefficient considered, the IQE peaks up at the low
injection current. And beyond the efficiency maximum, a more
rapid decrease of IQE is observed due to the effect of the
non-radiative term C(n2 p + p2 n). As the current is further
increased, the slope of IQE decrement becomes saturated. For
both devices, from Fig. 4(a), regardless of the consideration
of Auger recombination, the slops of IQE curves approach to
a nearly constant value at high current injections, indicating
the saturation of the effect of Auger.
The measured IQE follows the trend predicted by the
simulation with the Auger coefficient considered in Fig. 4(a).
As a result, the simulation indicates that in the GaN based
nanorod LED array, the effect of Auger plays a key role
in the efficiency decrease, especially at the low injection
currents.
B. Comparison Between Simulation and Experimental Results
Here we assume the extraction efficiency, defined as
the light output power divided by the internally generated light power, is the same in both devices. Also, the
strain obtained from the Raman measurement was employed
in the calculation. In Fig. 4(b), the measured and simulated IQEs of both devices are compared. The simulated
IQEs are normalized by the peak IQE value of LED-SOG.
The non-radiative carrier lifetimes of LED-SiO2 and LEDSOG are 1.81 × 108 s and 2.17 × 108 s, respectively. The
difference of carrier lifetime is associated with the capability of sidewall passivation using either SiO2 or SOG.
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IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 2, FEBRUARY 2013
(a)
(b)
(c)
(d)
Fig. 6. Electron densities (#/cm2 ) at (a) 3 mA (near the maximum IQE) at 100 mA and (b) LED-SOG (black lines) and LED-SiO2 (red lines). (c) and (d)
Corresponding band profiles at 3 and 100 mA, respectively, of both devices.
The lower carrier lifetime of LED-SiO2 may also be
attributed to the plasma damage during the PECVD deposition.
In Figure 4(b), the experimental data are well-fitted to the
simulated data.
Under high injection currents, IQE gradually decreases
and both devices show a similar slope. It implies that different degrees of strain relaxation can’t be the sole reason of the efficiency drop. The effect of strain is further divided to the carrier screening in the MQWs and
the carrier leakage out the wells. The percentage weightings of Auger recombination (defined as IAug/Itotal ) and
carrier leakage (defined as Ileak /Itotal ) are further extracted
from the simulation data and are shown in Fig. 5.
From the plot, IAug/Itotal quickly increases with the injection currents and saturates when the current is over
20mA for both devices. The rapid increase of Auger
recombination below 20mA contributes to a steeper decline
of the IQE at the onset of the efficiency maximum. And the
saturation of Auger beyond 20mA explains the steady decrease
of IQE in Fig. 4(b). On the other hand, Ileak /Itotal, even with a
less percentage value, increases almost linearly over the entire
current range except at the small current before the energy
levels filled up. In Fig. 5, Ileak /Itotal of LED-SOG is smaller
due to a more relaxed strain and less band tilt.
Even though both Auger recombination and carrier
overflow decreases the radiative recombination in the LED
structure, they carry different physical meanings. Auger
recombination occurs in the quantum well region while
carrier leakage represents the carriers which do not stay in
quantum wells. Despite a smaller percentage of Ileak /Itotal,
the effect of carrier overflow can be understood by plotting
carrier distribution in the quantum wells. Fig. 6(a) and (b)
show the simulated electron density distributions at the peak
IQE and at the injection current of 100mA, respectively, for
both devices. The p-type is placed on the left side while
the n-type is on the right. The electron density reaches
its maximum within five quantum wells and a significant
carrier leakage can be found at 100mA in the p-type GaN
(about three order of magnitude higher than the current at
peak IQE). Moreover, due to a more relaxed strain, carrier
CHEN et al.: EFFICIENCY DECREASE OF THE GaN LIGHT-EMITTING NANOROD ARRAYS
229
(a)
(b)
(c)
(d)
Fig. 7. EL spectra of (a) LED-SOG and (b) LED-SiO2 at the injection current ranging from 1 to 100 mA. (c) and (d) Close-up views of EL spectra within
the current range of 0–20 mA for LED-SOG and LED-SiO2 , respectively.
leakage in the case of LED-SOG is smaller than that in
LED-SiO2 .
To further investigate the correlation between carrier screening and band structure, Fig 6(c) and (d) show the simulated
band diagram of two types devises under different injection
currents. For both devices, flatter band profiles are observed
at 100mA, which indicates a more obvious screening effect,
as compared with the case at a smaller injection current. The
flatter band profile also indicates the optical transition energy
is different from the case at low level currents.
The band profile in Fig. 6 has enabled us to next conduct the
electroluminescence(EL) measurement for investigating the
optical transition energy within the quantum wells at various
carrier injections.
C. EL Measurement
The EL spectra were extracted with the injection current
ranging from 1mA to 100mA and are shown in Fig. 7.
The current dependent EL spectra reveal some interesting
correlations with the EQE decrease. The EL peak position of
LED-SOG is 2.720eV, 2.758eV and 2.785eV at the injection
current of 1mA, 20mA and 100mA, respectively. And for the
LED-SiO2 , the energy peak is 2.706, 2.755eV and 2.784eV
at injection current 1mA, 20mA and 100mA, respectively.
The peak energy difference suggests that under low carrier
injections (below 20mA), both devices demonstrate an obvious
blue shift with the increase of current (see the close-up views
in Fig. 7(c) and (d)). The larger blue shift of LED-SiO2 again
indicates QCSE in the MQWs is correlated to the strain [8].
And the screening of piezoelectric field results in a flatter
band profile which leads to higher EL peak energy. On the
other hand, at the high carrier injections (20 ∼ 100mA),
a relatively smaller energy peak shift is observed, which
indicates that strain relaxation isn’t as much a dominant factor
as that at lower currents. The phenomenon implies that since
the increased carriers are not fully contributed to radiative
recombination, part of them overflow out of the quantum wells
and mitigate the effect of carrier screening in the quantum
wells.
The above phenomena are next verified by simulation. Since
the self-consistent Poisson can also solve the Schrödinger
equation, the EL energy peaks are calculated based on the
optical transition between the confined energy states of the
conduction band and valence bands [17]. Fig. 8 shows both
the experimental and simulation results of the EL peak energy
shifts. For LED-SOG, the calculated energy shift is 43.8meV
(vs. 36.9meV in the measurement) at the injection currents
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IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 2, FEBRUARY 2013
R EFERENCES
Fig. 8. Comparisons of the EL peak shifts between the simulation and
measurement data.
between 1mA and 20mA and 20.2meV (vs. 26.9meV in the
measurement) at the current 20 ∼ 100mA. On the other hand,
we obtained a 52.0meV (vs. 49.3meV in the measurement)
shift at 1 ∼ 20mA and 21.6meV (vs. 28.2meV in the measurement) at 20 ∼ 100mA for LED-SiO2 . Although the simulation
results do not fully coincide with the measurement, they reveal
a certain consistency as both results have a larger peak shift
at lower currents and a smaller shift at large injections. The
phenomenon suggests that even the optical transition energy
becomes higher due to the carrier screening (carrier pile-up) as
the injection current is increased, a significant carrier overflow
to the barrier starts to be observed at the current larger than
20mA.
IV. C ONCLUSION
For the nanorod LED structure with different strains, the
dominant factors for efficiency decrease can be understood
from the experiment and simulation at various injection current levels. Our results on nanorods show that: first, Auger
recombination dominates the efficiency decrease near the EQE
maximum, and then it saturates at the higher current levels,
which contradicts general thought that the effect of Auger is
more obvious at high currents. The reason for the saturation of
Auger recombination is that carriers start to escape out of the
quantum wells, leading to the increase of leakage current and
the decrease of EQE at higher current levels. As a result, even
though the percentage weighting of Auger recombination is
much higher than that of the leakage current, the dominant
factor for efficiency drop becomes carrier leakage at high
currents. As compared with the planar structures, since the
strain in the nanorod InGaN/GaN MQWs is more relaxed, the
onset of carrier overflow occurs at a higher current level, and
thus the effect of Auger recombination is relatively easier to
be observed at low current levels. From the EL spectra, a
significant carrier overflow to the barrier starts to be observed
at the current of 20mA.
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Liang-Yi Chen received the B.S. degree in mechanical engineering and the M.S. degree from the
Graduate Institute of Photonics and Optoelectronics,
National Taiwan University, Taipei, Taiwan, in 2006
and 2008, respectively, where he is currently pursuing the Ph.D. degree.
His current research interests include fabrication
and theoretical calculation of the wideband-gap
materials and nanostructures.
Chi-Kang Li received the B.S. degree in mechanical
engineering and M.S. degree from the Graduate
Institute of Photonics and Optoelectronics, National
Taiwan University, Taipei, Taiwan, in 2007 and
2009, respectively, where he is currently pursuing
the Ph.D. degree.
His current research interests include simulation of
optoelectronic devices and high-power electronics.
231
Jin-Yi Tan received the B.S. degree in electrical engineering from National Taiwan University,
Taipei, Taiwan, in 2011, where he is currently pursuing the M.S. degree.
His current research interests include fabrication
and modulation characteristics of wide band-gap
materials and nanostructures.
Li-Chuan Huang received the B.S. degree in electrical engineering from National Tsing Hua University, Hsinchu, Taiwan, in 2010, where she is
currently pursuing the M.S. degree.
Her current research interests include fabrication and analysis of light efficiency of InGaN/GaN
nanorod light-emitting diode arrays.
Yuh-Renn Wu (S’02–M’07) received the B.S.
degree in physics and the M.S. degree in electrical engineering from National Taiwan University,
Taipei, Taiwan, in 1998 and 2000, respectively, and
the Ph.D. degree in electrical engineering from the
Department of Electrical Engineering and Computer
Science, University of Michigan, Ann Arbor, in
2006.
He is currently an Associate Professor with the
Institute of Photonics and Optoelectronic and the
Department of Electrical Engineering, National Taiwan University, where he is involved in research on physics, design of
optoelectronic devices, and high-power electronics. His current research
interests include studies of nitride-based quantum wells, quantum wires, and
quantum dot light-emitting diodes, high-power and high-speed electronics,
ferroelectrics, and optoelectronic devices.
Jian Jang Huang (M’98–SM’08) received the
B.S. degree in electrical engineering and the M.S.
degree from the Graduate Institute of Photonics and
Optoelectronics (GIPO), National Taiwan University
(NTU), Taipei, Taiwan, in 1994 and 1996, respectively, and the Ph.D. degree in electrical engineering
from the University of Illinois, Urbana-Champaign,
in 2002.
He is currently a Professor at GIPO, NTU, where
he is involved in research on applying nanostructures
to optoelectronic devices. He developed a spincoating method for nanosphere lithography, which can be applied to nanomaterials or nanostructures for significant performance improvement of light
emitting diodes, solar cells, and nanorod devices.
Prof. Huang was a recipient of numerous awards for his research contributions, including the Wu Da-Yu Award, the most prestigious one for young
researchers in Taiwan sponsored by National Science Council, in 2008 and
the award for the most excellent young electrical engineer from the Chinese
Institute of Electrical Engineering in 2008. He is a member of the Phi Tau
Phi Scholastic Honor Society. He is the Chair of the SPIE (San Diego, CA),
International Conference on Solid State Lighting, and the Board Director of
Global Communication Semiconductor, Inc., CA. He is the Editor of the IEEE
T RANSACTIONS ON E LECTRON D EVICES .