Browsing by Author "Kuo, Wei-Hung"

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High performance ultraviolet micro-LED arrays for fine-pitch micro displays
(2019-01-01)
Tsai, Yi-Lin
;
Huang, Yu-Ming
;
Yang, Shu-Mei
;
Kuo, Wei-Hung
;
Fang, Yen-Hsiang
Highly efficient ultraviolet micro LED arrays are demonstrated. Small devices (5 microns in size) suitable for high resolution (725 ppi) can be produced with low leakage current and good emission spectra stability. A 10 by 10 array is achieved with passive-matrix driving connection.
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
;
Lee, Ching-Ting
;
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.
The Aging Study for Fine Pitch Quantum-Dot Array on LEDs
(2019-01-01)
Huang, Yu-Ming
;
Liang, Kai-Ling
;
Cho, Yu-Yun
;
Hsu, Shun-Chieh
;
Kuo, Wei-Hung
In this paper, we fabricated the photoresist mold whose pitch is smaller than 15. m on light-emitting diode and printed two different cadmium-based quantum dots. Also, we burn-in the LED to compare their lifetime which are pasted barrier film by two different methods. (C) 2019 The Author(s)
Transparent electrode design for AlGaN deep-ultraviolet light-emitting diodes
(2017-12-11)
Hrong, Ray-Hua
;
Zeng, Yu-Yuan
;
Wang, Wei-Kai
;
Tsai, Chia-Lung
;
Fu, Yi-Keng
Zinc gallate (ZnGa2O4; ZGO) thin films were employed as the p-type transparent contact layer in deep-ultraviolet AlGaN-based light-emitting diodes (LEDs) to increase light output power. The transmittance of 200-nm-thick ZGO in deep-ultraviolet wavelength (280 nm) was as high as 92.3%. Two different ohmic contact structures, a dot-LED (D-LED; ZGO/dot-ITO/LED) and whole-LED (W-LED; ZGO/ITO/LED), exhibited improved light output power and current spreading compared to a conventional ITO-LED (C-LED). At an injection current of 20 mA, the D-LED and W-LED exhibited 33.7% and 12.3% enhancements in light output power, respectively, compared to the C-LED. The enhanced light output power of the D-LED can be attributed to an improvement in current spreading and enhanced light-extracting efficiency achieved by introducing ZGO/dot-ITO. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement