Browsing by Author "Kuo, Chien-Ting"

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A Single InN Nanopillar Photodetector with Extended Infrared Response Grown by MOCVD
(2016)
Hsu, Lung-Hsing
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Kuo, Chien-Ting
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Cheng, Yuh-Jen
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Chen, Kuan-Chao
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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.
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
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Kuo, Chien-Ting
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Cheng, Yuh-Jen
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Chen, Kuan-Chao
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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-based heterojunction photodetector with extended infrared response
(2015-11-30)
Hsu, Lung-Hsing
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Kuo, Chien-Ting
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Huang, Jhih-Kai
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Hsu, Shun-Chieh
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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
Numerical study of a highly efficient solar cell with graded band gap design
(2015-05-01)
Tan, Ming-Hsuan
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Tseng, Hung-Ruei
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Kuo, Chien-Ting
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Hsu, Shun-Chieh
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Lo, Yen-Hua
A linearly graded band gap design in the intrinsic layer of a p-i-n solar cell is studied numerically. An ideal model using Matlab (R) is built and the device performance is calculated using continuity equations and an effective band gap model under various band gap combinations. The power conversion efficiency (PCE) can be as high as 30.21%, while the abrupt junction reference device only exhibits 29.25% under the same parameters. This design is also evaluated using the commercial TCAD software APSYS (R), and the calculations show optimal efficiency enhancements of about 1.14-fold that of the abrupt junction device in an AlAs/GaAs system and 2.05-fold that in an InGaN/GaN system. (C) 2015 The Japan Society of Applied Physics
Site-controlled crystalline growth of InN on GaN substrate and its photoluminscence
(2016)
Kuo, Chien-Ting
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Hsu, Lung-Hsing
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Lai, Yung-Yu
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Kuo, Hao-Chung
;
Lin, Chien-Chung
We report a site-controlled growth of InN on a GaN substrate. Crystalline InN micropillars were selectively grown from the hexagonal V-pits on GaN surface. The grown mechanism and photoluminescent property will be discussed.
Site-controlled crystalline InN growth from the V-pits of a GaN substrate
(2017-05-31)
Kuo, Chien-Ting
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Hsu, Lung-Hsing
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Lai, Yung-Yu
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Cheng, Shan-Yun
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Kuo, Hao-Chung
A site-controlled crystalline InN growth from the V-pits of a GaN substrate was investigated. The V-pits were fabricated by epitaxial lateral growth of GaN over SiO2 disks patterned on a sapphire substrate. InN crystals were found to preferably grow on the inclined {10-11} crystal planes of the V-pits. A V-pit size of 1 mu m or less can provide precise site-controlled InN nucleation at the V-pit bottom, while no InN was grown on the rest of the exposed GaN surfaces. The site-controlled nucleation is attributed to the low surface energy point created by the converging six {10-11} crystal facets at the V-pit bottom. When In source supply is below a certain value, this V-pit bottom is the only location able to aggregate enough active sources to start nucleation, thereby providing site-controlled crystal growth. (C) 2017 Elsevier B.V.