Browsing by Author "Shu, Gia-Wei"

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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.
Measuring the Junction Temperature of GaInP/GaInAs/Ge Multijunction Solar Cells Using Photoluminescence
(2011-09-01)
Shu, Gia-Wei
;
Tung, Chiun-Hsiang
;
Tung, Shr-Chang
;
Su, Po-Chen
;
Shen, Ji-Lin
The junction temperatures of the three individual subcells of InGaP/InGaAs/Ge solar cells were measured using photoluminescence (PL) with three different excitation lasers. With the illumination of an extra xenon-mercury lamp, the linear relationship between the PL energy and the illumination level is clearly observed and advantageously used for deriving the junction temperature. Using the Varshni relationship between the PL peak energy and the heat-sink temperature allows us to determine the junction temperature in each subcell. (C) 2011 The Japan Society of Applied Physics
Optical and Electrical Properties of GaN-Based Light Emitting Diodes Grown on Micro- and Nano-Scale Patterned Si Substrate
(2011-07-01)
Chiu, Ching-Hsueh
;
Lin, Chien-Chung
;
Deng, Dong-Mei
;
Lin, Da-Wei
;
Li, Jin-Chai
We investigate the optical and electrical characteristics of the GaN-based light emitting diodes (LEDs) grown on micro-and nano-scale patterned silicon substrate (MPLEDs and NPLEDs). The transmission electron microscopy images reveal the suppression of threading dislocation density in InGaN/GaN structure on nano-pattern substrate due to nano-scale epitaxial lateral overgrowth. The plan-view and cross-section cathodo luminescence mappings show less defective and more homogeneous active quantum-well region growth on nano-porous substrates. From temperature-dependent photoluminescence (PL) and low temperature time-resolved PL measurement, NPLEDs have better carrier confinement and higher radiative recombination rate than MPLEDs. In terms of device performance, NPLEDs exhibit smaller electroluminescence peak wavelength blue shift, lower reverse leakage current and decrease in efficiency droop when compared with the MPLEDs. These results suggest the feasibility of using NPSi for the growth of high quality and power LEDs on Si substrates.