Browsing by Author "Hsu, Lung-Hsing"

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A Single InN Nanopillar Photodetector with Extended Infrared Response Grown by MOCVD
(2016)
Hsu, Lung-Hsing
;
Kuo, Chien-Ting
;
Cheng, Yuh-Jen
;
Chen, Kuan-Chao
;
Kuo, Hao-Chung
An extended infrared photoresponse is observed in a high quality InN pillar/p-GaN photodetector with self-assembly epitaxy grown by LP-MOCVD. The IR portion photocurrent as high as 14.2% can be measured via AM1.5G solar simulated spectra.
A ZnO/InN/GaN Heterojunction Photodetector with Extended Infrared Response
(2015)
Hsu, Lung-Hsing
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Hsu, Shun-Chieh
;
Lee, Hsin-Ying
;
Tsai, Yu-Lin
;
Lin, Da-Wei
An extended infrared photoresponse is observed in a ZnO/InN/GaN heterojunction diode with InN grown by MOCVD. The external quantum efficiency is measured between 1200 and 1800 nm and can be as high as 3.55%.
Effect of Sputtered AlN Location on the Growth Mechanism of GaN
(2017-01-01)
Wu, Pei-Yu
;
Li, Jhen-Hong
;
Hsu, Lung-Hsing
;
Huang, Chia-Yen
;
Cheng, Yuh-Jen
Patterned sapphire substrates (PSSs) have been used to enhance the performance of GaN-based light-emitting diodes (LEDs). This performance can be further improved by using an ex situ sputtered AlN nucleation layer. This improvement has been attributed to the reduction of the GaN formation on the sidewall of the cone shape pattern. In this study, four kinds of PSS samples were fabricated to investigate the effect of sputtered AlN location on the growth mechanism of GaN in detail. (c) 2017 The Electrochemical Society. All rights reserved.
Embedded InN Dot-Like Structure within InGaN Layers Using Gradient-Indium Content in Nitride-Based Solar Cell
(2013)
Hsu, Lung-Hsing
;
Lin, Chien-Chung
;
Tan, Ming-Hsuan
;
Yeh, Yun-Ling
;
Lin, Da-Wei
The novel design of embedded InN dot-like structure within InGaN was useful as an absorption layer in photovoltaic (PV) cells. We constructed the simulation model by employing the commercial software APSYS (R) and integrating the absorption coefficient of thin InN materials fabricated by metal organic vapor deposition (MOCVD). The model of simulating gradient Indium content of InGaN used as transition interface between InN and GaN was investigated. The results exhibit utilizing the effective variation of Indium content and suitable thickness to approach the optimal characteristic of hybrid InN/InGaN structure within solar cells shall be anticipated to enhance the performance of current nitride-based solar cells.
Embedded InN Dot-Like Structures with Modulating Growth Temperature in Nitride-Based Solar Cell
(2014-01-01)
Hsu, Lung-Hsing
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Lin, Chien-Chung
;
Han, Hau-Vei
;
Lin, Da-Wei
;
Kuo, Hao-Chung
The embedded InN dot-like structures within nitride-based solar cells is promising for extended visible and infrared absorption of solar spectrum. The temperature dependent InN epitaxial growth was demonstrated in a low-pressure metal organic chemical vapor deposition (MOCVD) system and the absorption coefficient of fabricated InN-dots was measured and integrated into APSYS (R) simulation platform. The dimension-quantization effect of the InN dot-like layer was investigated via photoluminescence (PL) measurements. Higher growth temperature region induces multiple PL peaks and blue-shift phenomenon, which could be attributed to variations in size and composition. The extracted absorption coefficients of InN-dot-like layer can be used to calculate the conversion efficiency of 2.34% for the corresponding GaN-based solar cell design.
Enhanced light harvesting of nitride-based nanopillars covered with ZnO using indium-tin oxide nanowhiskers
(2014-04-01)
Hsu, Lung-Hsing
;
Lin, Chien-Chung
;
Lee, Hsin-Ying
;
Huang, Jhih-Kai
;
Han, Hau-Vei
Nitride-based nanopillars were successfully fabricated by nanoimprint lithography. A nanowhisker of indium-tin oxide (ITO) deposited by on oblique evaporation method was investigated in nitride-based nanopillars and thin ZnO layers grown by atomic layer deposition (ALD). From the results of field-emission scanning electron microscopy (SEM) measurement, it was found that ITO whiskers grew on nitride-based nanopillars covered with ZnO. Moreover, from the results of UV-visible spectrophotometry and bidirectional reflectance distribution function (BRDF) measurements, it was found that this hybrid structure of ITO nanowhiskers above a ZnO medium enhanced the broadband and angle-independent antireflection in the range between 380 and 600nm. We used the hybrid design of the ITO/ZnO structure to achieve the lowest reflectance value between 3.8 and 10.9% in a quantum well absorption range. (C) 2014 The Japan Society of Applied Physics
Enhanced photocurrent of a nitride-based photodetector with InN dot-like structures
(2014-12-01)
Hsu, Lung-Hsing
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Lin, Da-Wei
;
Lo, Yen-Hua
The InN dot-like layer was applied in the gallium nitride based material for the purpose of infrared photodetectors (PDs). This InN layer was grown by a low-pressure metal organic chemical vapor deposition technology under different growth temperatures. The X-ray diffraction patterns provide the information of crystal structure and the hexagonal orientation was detected. The Raman shifts and photoluminescence were also used to characterize the quality of InN film. Finally, the fabricated Schottky-type photodetector was tested under a solar simulator and a long-wavelength laser (lambda = 1550nm). The measurements show a highly linear relation between photo-generated currents and laser powers for the wavelength of 1550 nm. In the photonic detection range suitable for optical fiber communiation, a quantum efficiency of 9.2% can be observed. (C) 2014 Optical Society of America
Enhanced Photoresponse of InN Devices Using Indium-Tin Oxide Nanorods
(2017-01-01)
Hsu, Lung-Hsing
;
Cheng, Yuh-Jen
;
Yu, Peichen
;
Kuo, Hao-Chung
;
Lin, Chien-Chung
Enhanced infrared photoresponse is observed in InN/ITO rods fabricated by LP-MOCVD and oblique-angle electron beam evaporation. The higher growth temperature and more V/III could trend toward hexagonal InN pillars epitaxy. The peak energy blue-shift phenomenon due to higher Fermilevel to acceptor emission was investigated by temperature dependent photoluminescence (PL) measurements. ITO nanorods enhanced the broadband and angle-independent anti-reflection in the range between 400 nm and 2000 nm. The InN/ITO rods photodetection device was demonstrated with enhanced IR response, and the portion photocurrent (610 nm long pass) of InN detection as high as 24.5% measured via AM1.5G solar simulated spectra.
Enhanced power conversion efficiency in InGaN-based solar cells via graded composition multiple quantum wells
(2015-11-30)
Tsai, Yu-Lin
;
Wang, Sheng-Wen
;
Huang, Jhih-Kai
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Hsu, Lung-Hsing
;
Chiu, Ching-Hsueh
This work demonstrates the enhanced power conversion efficiency (PCE) in InGaN/GaN multiple quantum well (MQWs) solar cells with gradually decreasing indium composition in quantum wells (GQWs) toward p-GaN as absorber. The GQW can improve the fill factor from 42% to 62% and enhance the short current density from 0.8 mA/cm(2) to 0.92 mA/cm(2), as compares to the typical MQW solar cells. As a result, the PCE is boosted from 0.63% to 1.11% under AM1.5G illumination. Based on simulation and experimental results, the enhanced PCE can be attributed to the improved carrier collection in GQW caused by the reduction of potential barriers and piezoelectric polarization induced fields near the p-GaN layer. The presented concept paves a way toward highly efficient InGaN-based solar cells and other GaN-related MQW devices. (C) 2015 Optical Society of America
Enhanced Radiative Emission of MQW by Resonant Modes of Hyperbolic Metamaterial Resonator
(2019-01-01)
Shen, Kun-Ching
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Hsu, Lung-Hsing
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Tsai, Din Ping
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Kuo, Hao-Chung
;
Lin, Chien-Chung
We report the use of resonant modes of a hyperbolic metamaterial cube made of multiple metal/dielectric layer structure to enhance the radiative emission of multiple quantum wells. The mode analysis and photoluminescence will be discussed. (C) 2019 The Author(s)
Influence of the microstructure geometry of patterned sapphire substrates on the light extraction efficiency of GaN LEDs
(2016-09)
Kuo, Chien-Ting
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Hsu, Lung-Hsing
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Huang, Bo-Hsin
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Kuo, Hao-Chung
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Lin, Chien-Chung
The influence of the microstructure geometry of patterned sapphire substrates (PSS) on the light extraction efficiency (LEE) of GaN light-emitting diodes (LEDs) is numerically analyzed. Cone structures of various dimensions are studied, along with dome and mixed microstructures. LEE is found to mainly depend on the microstructure surface slope. LEE rises quickly with slope and flattens out when the slope exceeds 0.6. Scaling down the microstructure has little effect on LEE. Light rays are found to travel longer distances in PSS LEDs, as compared with LEDs grown on a flat substrate. Keeping GaN absorption loss low is important for LEE optimization. (C) 2016 Optical Society of America
InN Nanopillar Devices with Strong Photoresponse
(2016-01-01)
Hsu, Lung-Hsing
;
Kuo, Chien-Ting
;
Cheng, Yuh-Jen
;
Chen, Kuan-Chao
;
Kuo, Hao-Chung
The InN pillars/p-GaN is promising for extended visible and infrared absorption. The higher growth temperature and more V/III could trend toward hexagonal InN pillars epitaxy, fabricated by a low-pressure metal organic chemical vapor deposition. The tensile strain effect and the peak energy blue-shift phenomenon due to higher Fermi-level to acceptor emission were investigated via Raman and photoluminescence (PL) measurements. The high quality InN pillars reveal no indium droplets by X-ray diffraction pattern. A InN pillars photodetection device is demonstrated with extended IR response, and the portion photocurrent of InN detection as high as 13% measured via AM1.5G solar simulated spectra.
InN Nanopillar Photodetector with Enhanced Infrared Response Using Indium-Tin Oxide Nanorods
(2017-01-01)
Hsu, Lung-Hsing
;
Cheng, Yuh-Jen
;
Yu, Peichen
;
Kuo, Hao-Chung
;
Lin, Chien-Chung
Enhanced infrared photoresponse is observed in InN pillars/ITO rods photodetectors fabricated by LP-MOCVD and oblique-angle electron beam evaporation. The enhanced IR portion photocurrent as high as 19% can be measured via AM1.5G solar simulated spectra.
InN-based heterojunction photodetector with extended infrared response
(2015-11-30)
Hsu, Lung-Hsing
;
Kuo, Chien-Ting
;
Huang, Jhih-Kai
;
Hsu, Shun-Chieh
;
Lee, Hsin-Ying
The combination of ZnO, InN, and GaN epitaxial layers is explored to provide long wavelength photodetection capability in the GaN based materials. Growth temperature optimization was performed to obtain the best quality of InN epitaxial layer in the MOCVD system. The temperature dependent photoluminescence (PL) can provide the information about thermal quenching in the InN PL transitions and at least two non-radiative processes can be observed. X-ray diffraction and energy dispersive spectroscopy are applied to confirm the inclusion of indium and the formation of InN layer. The band alignment of such system shows a typical double heterojunction, which is preferred in optoelectronic device operation. The photodetector manufactured by this ZnO/GaN/InN layer can exhibit extended long-wavelength quantum efficiency, as high as 3.55%, and very strong photocurrent response under solar simulator illumination. (C) 2015 Optical Society of America
Light Extraction Enhancement of GaN-Based Light-Emitting Diodes Using Crown-Shaped Patterned Sapphire Substrates
(2012-07-15)
Chiu, Ching-Hsueh
;
Hsu, Lung-Hsing
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Lee, Chia-Yu
;
Lin, Chien-Chung
;
Lin, Bo-Wen
In this letter, we report the high performance GaN-based light-emitting diodes (LEDs) with embedded air void array grown by metal-organic chemical vapor deposition. The donut-shaped air void was formed at the interface between crown-shaped patterned sapphire substrates (CPSS) and the GaN epilayer by conventional photolithography. The transmission electron microscopy images demonstrate that the threading dislocations were significantly suppressed by epitaxial lateral overgrowth (ELOG). The Monte Carlo ray-tracing simulation reveals that the light extraction of the air-voids embedded LED was dramatically increased due to a strong light reflection and redirection by the air voids.
Numerical Study on Doping and Positioning Effect of Type-II GaSb/GaAs Quantum Ring Layer on Solar Cell Performances
(2016-01-01)
Wu, Po-Ching
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Hsu, Shun-Chieh
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Jhen, Yun-Han
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Dong, Yao-Zhong
;
Ling, Yan-Zhang
In this work, we demonstrate the doping concentration and positioning effect of the type-II quantum well (QR) on the solar cell performances in terms of numerical simulation. The variation in doping concentration and location can affect the band diagram seriously and possibly form the back surface field which can either facilitate or deteriorate the carrier collection. A wide range of parameters are calculated to reveal this trend and the previous experimental results are also discussed.
Optical influence of a hybrid ZnO/Indium-Tin-Oxide Nano-Rod and Whisker
(2015)
Hsu, Lung-Hsing
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Lee, Hsin-Ying
;
Lin, Da-Wei
;
Kuo, Hao-Chung
;
Yu, Peichen
The nano-whisker and nano-rod of ITO deposited with oblique evaporation method has been investigated optically. This ITO hybrid structure above ZnO medium reduces optical reflection to 3.7% in the range between 365 and 800 nm.
Optical Properties of InN-Based Photo detection Devices
(2015)
Hsu, Lung-Hsing
;
Lin, Chien-Chung
;
Hwang, Yi-Chia
;
Su, Chen-Fung
;
Lin, Shih-Yen
The InN capped with GaN structures is promising for extended visible and infrared absorption. The low growth temperature of GaN/InN epitaxy was fabricated by a low-pressure metal organic chemical vapor deposition system. The strain effect and mixed InxGa1-xN complex of the GaN/InN layer were investigated via Raman and photoluminescence (PL) measurements. The capping GaN with similar growth temperature of previous InN growth induces the gallium diffusion mechanism to form InxGa1-xN complex. The blue-shift phenomenon of multiple GaN/InN peaks with increasing growth temperature was attributed to residual strain and higher Ga content of InGaN. A ZnO/GaN/InN photodetection device is demonstrated with extended IR response, and the quantum efficiency is 2.28%.
Optical Properties of Patterned InN in Photodetection Devices
(2018-01-01)
Hsu, Lung-Hsing
;
Cheng, Yuh-Jen
;
Yu, Peichen
;
Kuo, Hao-Chung
;
Lin, Chien-Chung
InN selective-area-growth on patterned GaN templates was employed by nano-imprint lithography and LP-MOCVD epitaxy. ITO rods were deposited by oblique-angle electron beam evaporation. The X-ray diffraction patterns provide the hexagonal orientation of patterned InN crystals. The broad band signal and peak energy blue-shift phenomenon due to higher Fermi-level to acceptor emission were investigated by photoluminescence (PL). The Raman-shifts characterized the high-quality patterned InN growth. InN nanostructures/ITO rods enhanced broadband and angle-independent anti-reflection. It was demonstrated with near-infrared response by a tunable laser illumination (1470 similar to 1580nm), and the portion photocurrent (920 nm long pass) exhibits 33% measured via AM1.5G solar simulated spectra.
Purely Sidewall InGaN/GaN Core-Shell Nanorod Green Light-Emitting Diodes
(2015)
Lin, Da-Wei
;
Wu, Yung-Chi
;
Kuo, Hao-Chung
;
Chi, Gou-Chung
;
Hsu, Lung-Hsing
A novel purely sidewall InGaN/GaN core-shell nanorod green light-emitting diode (LED) has been demonstrated by 3D dielectric passivation and selective epitaxial growth technologies. The LED device exhibits unprecedented stable emission wavelength and low efficiency droop.