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Research
Accomplishments in 2009, Wide Gap
Semiconductor Laboratory
Professor
Zhe-Chuan Feng
Graduate Institute of Photonics and
Optoelectronics, National Taiwan
University
台湾大学光电所
冯哲川教授
l“Raman
scattering study on anisotropic property
of wurtzite GaN”,
Hung Chiao Lin,
Z.C. Feng,
et al., JOURNAL OF APPLIED
PHYSICS 105, 036102 (2009).
l“Temperature
dependent and time-resolved
photoluminescence studies of InAs
self-assembled quantum dots with InGaAs
strain reducing layer structure”,
Lingmin Kong, Zhe Chuan
Feng, et al.,
JOURNAL OF APPLIED PHYSICS 106,
013512 (2009)
l“Suppression
of phase separation in InGaN layers
grown on lattice-matched ZnO substrates”,
N. Li, … Z.C. Feng, et al.,
Journal of Crystal Growth
311 (2009) 4628–4631.
l“Rapid
thermal annealing effects on the
structural and optical properties of ZnO
films deposited on Si substrates”,
Y.C. Lee, … Z.C. Feng, et al.,
J. Luminescence 129
(2009) 148–152.
l“Metalorganic
chemical vapour deposition of GaN layers
on ZnO substrates using
α-Al2O3
as a transition layer”,
S.J. Wang, … Z.C. Feng, et al.,
J. Phys. D: Appl. Phys.
42 (2009) 245302 (5pp).
l“Temperature-Dependent
Excitonic Luminescence in ZnO Thin Film
Grown by Metal Organic Chemical Vapor
Deposition”,
Y.C. Lee, … Z.C. Feng, et al.,
Japanese Journal of
Applied Physics 48 (2009) 112302.
Enhancing
InGaN-based solar cell efficiency
through localized surface plasmon
interaction by embedding Ag
nanoparticles
Professor Yean-Woei
Kiang's Laboratory
Graduate Institute of Photonics and
Optoelectronics, National Taiwan
University
台湾大学光电所
江衍伟教授
We have demonstrated the
simulation results of using the
interaction of metal NP induced LSP with
an InGaN absorbing layer for enhancing
the efficiency of an InGaN/GaN-based
solar cell. The absorption increase is
implemented by embedding Ag NPs in InGaN
for inducing LSP. The effective LSP
absorption and NP scattering lead to the
enhancement of InGaN absorption. The
embedment of metal NPs in semiconductor
may affect carrier transport. However,
we show that such an effect is small
unless the surface recombination
velocity at the interface between a
metal NP and surrounding InGaN is
extremely high. Fig. 1 shows the photon
absorption rates (the left ordinate) of
the InGaN layer and Ag NP and the
short-circuit current densities (the
right ordinate) of the solar cell as
functions of wavelength for the cases
with and without Ag NP when the surface
recombination velocity, S, is 10 m/s.
For comparison, the incident photon flux
under the condition of AM1.5G (the curve
labeled by “incidence”) is also plotted
in Fig. 1. The significant absorption
enhancement on the long-wavelength side
by embedding the Ag NP can be clearly
seen. In Fig. 1, the curve labeled by
“metal dissipation” represents the part
of photons absorbed by the Ag NP and
turned into dissipation heat. The
embedment of the Ag NP results in an
increase of integrated photon absorption
rate by 28.44 %. The two curves of
short-circuit current density (per unit
spectral width), i.e., JSC (without NP)
and JSC (with NP), which essentially
follow the oscillatory behaviors of the
two curves for InGaN absorption show the
enhancement of photo-generated current.
With the embedded Ag NP, the integrated
JSC is increased by 27.87 %. Fig. 2(a)
shows the distribution of electrical
field magnitude at 580 nm in the region
around the Ag NP by assuming that the
magnitude of the incident field is
unity. Here, one can see that strong
near field is generated around the Ag
NP. Also, certain backscattered field is
distributed in the n-GaN layer. Fig.
2(b) shows the stream line distribution
of static electric field inside the
solar cell. Here, one can see the
distortion of static electric field by
the embedded Ag NP. Fig. 3 shows the
integrated current densities (the left
ordinate) and the output power densities
(the right ordinate) as functions of
applied voltage for the cases with NP
and without NP corresponding to the
results shown in Fig. 1. The first and
second numbers in the parentheses
represent the voltage for the maximum
output power (in V) and the maximum
output power density (in mW/cm2).
Here, one can see that the open-circuit
voltage of ~1.51 V is not affected by
the embedment of the Ag NP. The
integrated current density, J, is
significantly increased from 8.08 to
10.17 mA/cm2 by embedding the
Ag NP. The maximum output powers of both
cases are achieved at 1.4 V in applied
voltage. The maximum output power is
increased from 10.59 to 13.53 mW/cm2
(roughly from 10.59 to 13.53 % in
efficiency), corresponding to an
increase of 27.76 %.
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