Browsing by Author "Lee, Yueh-Chien"

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Enhanced Conversion Efficiency of GaAs Solar Cells Using Ag Nanoparticles
(2010-12-01)
Shu, Gia-Wei
;
Liao, Wei-Chuan
;
Hsu, Ching-Ling
;
Lee, Ja-Yuan
;
Hsu, I-Jen
We have studied the enhancement of conversion efficiency in GaAs solar cells using silver nanoparticles with particle average sizes between 11.4 to 17.2 nm. The maximum enhancement of 20.2% in conversion efficiency is achieved for the GaAs solar cells where the Ag nanoparticles have been incorporated. The simulations according to Mie theory suggest that the increased radiative scattering and conversion efficiency is due to a combined effect of the surface plasmon resonance and the interband transition.
Green Light-emitting Diodes with InGaN/GaN Multiple Quantum Well Structures: Time-resolved Photoluminescence, Emission Dynamics and Related Studies
(2016)
Feng, Zhe Chuan
;
Jiang, Xiaodong
;
Lee, Yueh-Chien
;
Kuo, Hao-Chung
;
Wan, Lingyu
To explore the mechanism, breakthrough the current bottleneck and overcome the efficiency droop from green InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs). The photoluminescence properties and carrier dynamics of green InGaN/GaN MQW LEDs are investigated by temperature-dependent photoluminescence (PL) from 10 K to 300 K and time-resolved PL (TRPL) measurements at 10 K in our new-built lab. With increasing temperature, a blue shift of PL behavior is attributed to band-tail states formed in local potential minima resembling In-rich clusters. The energy-dependent TRPL experiments are measured at 10 K to study the carrier dynamics in the MQWs. The results show that the PL slow decays for the low-energy side are much slower than the high-energy side. The depth of carrier localization is obtained by fitting the reduced slow decay time with the emission energy increasing. All the results indicate that the PL peak is related to localized radiative recombination.
Investigation of omnidirectional reflection band in ZnTe/ZnSe distributed Bragg reflector
(2015-11-15)
Huang, Ying-Shin
;
Hu, Sheng-Yao
;
Lee, Yueh-Chien
;
Chang, Chung-Cheng
;
Tiong, Kwong-Kau
We report the characteristics of reflectance spectra of the 15- and 20-period ZnTe/ZnSe distributed Bragg reflector grown on GaAs (001) substrates by molecular beam epitaxy. The reflectance spectra measured at various incident angles and polarizations were investigated by the theoretical curves simulated using transfer matrix method. The wavelength variation of the refractive indices described by Sellmeier equation and random thickness model were also considered for the interpretation of the experimentally observed curves. An omnidirectional reflection range defined from the edge of incident-angle-dependent reflection band with TE and TM polarizations is about 15 nm, and is consistent with the observed experimental curves. The results showed that the selected ZnTe and ZnSe materials are suitable for constructing multilayer structures having omnidirectional reflection band. (C) 2015 Elsevier B.V. All rights reserved.