Browsing by Author "Lee, Hsin-Ying"

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A ZnO/InN/GaN Heterojunction Photodetector with Extended Infrared Response
(2015)
Hsu, Lung-Hsing
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Hsu, Shun-Chieh
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Lee, Hsin-Ying
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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%.
Characteristics of atomic layer deposition-grown zinc oxide thin film with and without aluminum
(2019-10-15)
Tseng, Ming-Chun
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Wuu, Dong-Sing
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Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Chien, Cheng-Yu
Zinc oxide (ZnO) and Al-doped ZnO (AZO) thin films were deposited on glass substrates using atomic layer deposition. The Al composition of the AZO thin films was varied by controlling the Zn:Al cycle ratios. The ZnO and AZO thin films were characterized using atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and optical measurements. The electrical properties of the ZnO and AZO thin films were influenced by the Zn:Al cycle ratios. The resistivity of the AZO thin film decreased significantly, whereas the carrier concentration increased with the Al composition. As the Zn:Al cycle ratio increased, the AZO thin film achieved an average transmittance of > 85%.
Enhanced light extraction in wafer-bonded p-side-up thin-film AlGaInP light emitting diodes via zinc oxide nanorods
(2016-10-01)
Tseng, Ming-Chun
;
Wuu, Dong-Sing
;
Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Lin, Yu-Chang
ZnO nanorods grown via hydrothermal method on the aluminum-doped zinc oxide (AZO) thin film were used to fabricate high-brightness p-side-up thin-film AlGaInP light-emitting diodes (LEDs). The AZO thin film was not only used as current spreading layers but also as a seed layer of ZnO nanorods. The AZO thin film was prepared using atomic layer deposition. The ZnO nanorods improved light extraction, thus increasing the light output power of the LEDs. The output powers of LEDs with optimum ZnO nanorod structures were increased by 32% at an injection current of 700 mA, as compared with that of an LED with AZO thin film. The emission wavelength shifts of LEDs with an AZO thin film and optimum ZnO nanorod structure were 18 and 11 nm, respectively, when the injection current was increased from 20 to 1000 mA. The ZnO nanorods not only provide more light extraction but also keep the thermal stability of the LED device without any degradation. The results are promising for the developed high brightness AlGaInP LED applications with low fabrication cost through ZnO nanorods grown by hydrothermal method to enhance the light extraction efficiency. (C) 2016 Optical Society of America
Enhanced light harvesting of nitride-based nanopillars covered with ZnO using indium-tin oxide nanowhiskers
(2014-04-01)
Hsu, Lung-Hsing
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Lin, Chien-Chung
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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
Improved Accuracy Factors for the Nonuniform Fast Fourier Transform (NUFFT) Algorithm
(2009-01-01)
Kuo, Jen-Tsai
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Lee, Hsin-Ying
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電信工程研究所
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Institute of Communications Engineering
Based on the regular Fourier matrix, a new set of accuracy factors is proposed for the nonuniform fast Fourier transform algorithm to improve the accuracy of transformed data. It shows that the proposed factors can reduce the errors by three to more than ten times with almost the same number of arithmetic operations. Numerical examples are shown for the applications in computational electromagnetics.
Improved Color Purity of Monolithic Full Color Micro-LEDs Using Distributed Bragg Reflector and Blue Light Absorption Material
(2020-05-01)
Chu, Shao-Yu
;
Wang, Hung-Yu
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Lee, Ching-Ting
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Lee, Hsin-Ying
;
Laing, Kai-Ling
In this study, CdSe/ZnS core-shell quantum dots (QDs) with various dimensions were used as the color conversion materials. QDs with dimensions of 3 nm and 5 nm were excited by gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with a size of 30 mu m x 30 mu m to respectively form the green and red lights. The hybrid Bragg reflector (HBR) with high reflectivity at the regions of the blue, green, and red lights was fabricated on the bottom side of the micro-LEDs to reflect the downward light. This could enhance the intensity of the green and red lights for the green and red QDs/micro-LEDs to 11% and 10%. The distributed Bragg reflector (DBR) was fabricated on the QDs color conversion layers to reflect the non-absorbed blue light that was not absorbed by the QDs, which could increase the probability of the QDs excited by the reflected blue light. The blue light absorption material was deposited on the DBR to absorb the blue light that escaped from the DBR, which could enhance the color purity of the resulting green and red QDs/micro-LEDs to 90.9% and 90.3%, respectively.
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
;
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
Ohmic contact behavior of aluminum-doped zinc oxide with carbondoped p-GaP epilayer for AlGaInP LEDs applications
(2017-07-01)
Tseng, Ming-Chun
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Wuu, Dong-Sing
;
Chen, Chi-Lu
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Lee, Hsin-Ying
;
Horng, Ray-Hua
Aluminum-doped zinc oxide (AZO) thin films used for ohmic contact layers on carbon-doped GaP window layers (p-GaP:C) of AlGaInP light-emitting diodes were fabricated and characterized. AZO thin films with different Zn:Al cycle ratios (15:1, 20:1, and 25:1) were deposited on p-GaP:C window layers through atomic layer deposition. The contact characteristics of the AZO thin films on p-GaP:C were considerably changed from Schottky contact to ohmic contact after rapid thermal annealing (RTA) at 350 degrees C for 1 min. The most favorable specific contact resistance of AZO/p-GaP:C was evaluated using a circular transmission line model as 6.3 x 10(-3) Omega/cm(2). Angle-resolved X-ray photoelectron spectroscopy was employed to understand the ohmic contact behavior of AZO/p-GaP:C. After RTA, Zn atoms in the AZO thin films notably diffused into the p-GaP:C layers and Ga atoms diffused out of the p-GaP:C layer. Therefore, the Ga vacancies were occupied by Zn atoms, which increased the doping concentration in the near-surface region of p-GaP:C and reduced the depletion region width of the semiconductor region. Thus, numerous carriers were able to tunnel through the reduced Schottky barrier and those carriers produced the ohmic contact behavior between the AZO and p-GaP:C. (C) 2017 Elsevier B. V. All rights reserved.
Optical influence of a hybrid ZnO/Indium-Tin-Oxide Nano-Rod and Whisker
(2015)
Hsu, Lung-Hsing
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Lee, Hsin-Ying
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Lin, Da-Wei
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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.
Performance comparison of p-side-up thin-film AlGaInP light emitting diodes with aluminum-doped zinc oxide and indium tin oxide transparent conductive layers
(2016-04-01)
Tseng, Ming-Chun
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Wuu, Dong-Sing
;
Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Lin, Yu-Chang
Transparent conductive layers (TCLs) deposited on a GaP window layer were used to fabricate high-brightness p-side-up thin-film AlGaInP light-emitting diodes (LEDs) by the twice wafer-transfer technique. Indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) were used as TCLs for comparison. The TCLs improved droop of external quantum efficiencies (EQE) of LEDs and junction temperature, which result in increasing the light output power and thermal stability of the LEDs. The droop efficiency of Ref-LED, ITO-LED and AZO-LED were 64%, 27% and 15%, respectively. The junction temperature of ITO-LED and AZO-LED reduced to 49.3 and 39.6 degrees C at an injection current of 700 mA compared with that (80.8 degrees C) of Ref-LED. The LEDs with AZO layers exhibited the most excellent LED performance. The emission wavelength shifts of LEDs without a TCL, with an ITO layer, and with an AZO layer were 17, 8, and 3 nm, respectively, when the injection current was increased from 20 to 1000 mA. The above results are promising for the development of AZO thin films to replace ITO thin films for AlGaInP LED applications. (C) 2016 Optical Society of America
Performance of p-side-up thin-film AlGaInP light-emitting diodes with textured composite aluminum-doped zinc oxide transparent conductive layers
(2017-06-25)
Tseng, Ming-Chun
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Wuu, Dong-Sing
;
Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Lin, Yu-Chang
Composite transparent conductive layers (TCLs) were deposited on the GaP window layer of p-side-up thin-film AlGaInP light-emitting diodes (LEDs) in order to enhance their light-extraction efficiency. The composite TCLs were fabricated from aluminum-doped zinc oxide (AZO) layers grown through atomic-layer deposition and pulsed-laser deposition. The results showed that wet-etching of composite AZO thin films improved the light extraction efficiency of the corresponding LED devices. The droop efficiencies of LEDs with flat AZO thin films, composite AZO thin films, and optimum textured composite AZO thin films were 29%, 30%, and 22%, respectively. LEDs with textured composite AZO layers exhibited favorable optoelectronic performance. When the injection current was increased from 20 to 1000 mA, the emission wavelengths of LEDs with flat AZO thin films, composite AZO thin films, and optimum textured composite AZO thin films shifted by 3, 5, and 3 nm, respectively. The optimum textured composite AZO thin film can not only improve LED performance but also effectively substitute flat TCLs in AlGaInP LED applications. (C) 2016 Elsevier B.V. All rights reserved.
Zinc oxide-based current spreading layer behavior on the performance of P-side-up thin-film red light emitting diodes
(2018-02-28)
Tseng, Ming-Chun
;
Wuu, Dong-Sing
;
Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Horng, Ray-Hua
Transparent conductive layers deposited on a GaP window layer were used to fabricate high-brightness p-side-up thin-film AlGaInP light emitting diodes (LEDs). Zinc oxide (ZnO) and aluminum-doped zinc oxide (ZAO) with an Zn:Al cycle ratio of 20:1 were grown by atomic layer deposition for comparison. The ZAO thin films reduced the droop in the external quantum efficiencies of the LEDs as well as the junction temperature, which result in increases in the light output power and thermal stability of the LEDs. The efficiency droops of the LEDs with the ZnO and ZAO thin films were 41% and 15%, respectively. The junction temperature of the LED with the ZAO thin film can be reduced to 39.6 degrees C at an injection current of 700 mA, which is lower than that of the LED with the ZnO thin film (58.1 degrees C). The above results are promising for the development of ZAO thin films for applications in AlGaInP LEDs. (C) 2017 Elsevier B.V. All rights reserved.