Browsing by Author "Song, Jie"

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Full-color micro-LED display with high color stability using semipolar (20-21) InGaN LEDs and quantum-dot photoresist
(2020-05-01)
Chen, Sung-Wen Huang
;
Huang, Yu-Ming
;
Singh, Konthoujam James
;
Hsu, Yu-Chien
;
Liou, Fang-Jyun
Red-green-blue (RGB) full-color micro light-emitting diodes (mu-LEDs) fabricated from semipolar (20-21) wafers, with a quantum-dot photoresist color-conversion layer, were demonstrated. The semipolar (20-21) InGaN/GaN mu-LEDs were fabricated on large (4 in.) patterned sapphire substrates by orientation-controlled epitaxy. The semipolar mu-LEDs showed a 3.2 nm peak wavelength shift and a 14.7% efficiency droop under 200 A/cm(2 )injected current density, indicating significant amelioration of the quantum-confined Stark effect. Because of the semipolar mu-LEDs' emission-wavelength stability, the RGB pixel showed little color shift with current density and achieved a wide color gamut (114.4% NTSC space and 85.4% Rec. 2020). (C) 2020 Chinese Laser Press
High-Bandwidth Green Semipolar (20-21) InGaN/GaN Micro Light-Emitting Diodes for Visible Light Communication
(2020-08-19)
Chen, Sung-Wen Huang
;
Huang, Yu-Ming
;
Chang, Yun-Han
;
Lin, Yue
;
Liou, Fang-Jyun
The light-emitting diode (LED) is among promising candidates of light sources in visible light communication (VLC); however, strong internal polarization fields in common c-plane LEDs, especially green LEDs, result in low frequency and limited transmission performance. This study aims to overcome the limited 3-dB bandwidth of long-wavelength InGaN/GaN LEDs. Thus, semipolar (20-21) micro-LEDs (mu LEDs) were fabricated through several improved approaches on epitaxy and chip processes. The mu LED exhibits a 525 nm peak wavelength and good polarization performance. The highest 3-dB bandwidth up to 756 MHz and 1.5 Gbit/s data rate was achieved under a current density of 2.0 kA/cm(2). These results suggest a good transmission capacity of green semipolar (20-21) mu LEDs in VLC applications.
Significantly Improved Luminescence Properties of Nitrogen-Polar (000(1over bar>)over-bar) InGaN Multiple Quantum Wells Grown by Pulsed Metalorganic Chemical Vapor Deposition
(2015-01-14)
Song, Jie
;
Chang, Shih-Pang
;
Zhang, Cheng
;
Hsu, Ta-Cheng
;
Han, Jung
We have demonstrated nitrogen-polar (000 (1) over bar) (N-polar) InGaN multiple quantum wells (MQWs) with significantly improved luminescence properties prepared by pulsed metalorganic chemical vapor deposition. During the growth of InGaN quantum wells, Ga and N sources are alternately injected into the reactor to alter the surface stoichiometry. The influence of flow duration in pulsed growth mode on the luminescence properties has been studied. We find that use of pulsed-mode creates a high density of hexagonal mounds with an increased InGaN growth rate and enhanced In composition around screw-type dislocations, resulting in remarkably improved luminescence properties. The mechanism of enhanced luminescence caused by the hexagonal mounds is discussed. Luminescence properties of N-polar InGaN MQWs grown with short pulse durations have been significantly improved in comparison with a sample grown by a conventional continuous growth method.