Browsing by Author "Liu, Mei-Chun"

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Electrically driven green, olivine, and amber color nanopyramid light emitting diodes
(2013-10-07)
Chang, Shih-Pang
;
Chang, Jet-Rung
;
Sou, Kuok-Pan
;
Liu, Mei-Chun
;
Cheng, Yuh-Jen
We report the fabrication and studies of electrically driven green, olivine, and amber color nanopyramid GaN light emitting diodes (LEDs). InGaN/GaN multiple quantum wells (MQWs) were grown on the nanopyramid semipolar facets. Compared with the commonly used (0001) c-plane MQWs, the semipolar facet has lower piezoelectric field, resulting in much faster radiative recombination efficiency. This is important for high In content MQWs. The measured internal quantum efficiencies for green, olivine, and amber color LED are 30%, 25%, and 21%, respectively. The radiative and non-radiative lifetime of the semipolar MQWs are also investigated. (C) 2013 Optical Society of America
Lasing at exciton transition in optically pumped gallium nitride nanopillars
(2011-09-12)
Lo, Ming-Hua
;
Cheng, Yuh-Jen
;
Liu, Mei-Chun
;
Kuo, Hao-Chung
;
Wang, Shing Chung
We report the observation of room temperature lasing action in optically pumped GaN nanopillars. The nanopillars were fabricated by patterned etching and crystalline regrowth from a GaN substrate. When nanopillars were optically excited, a narrow emission peak emerged from the broad spontaneous emission background. The increasing rate is nine times faster than that of the spontaneous emission background, showing the onset of lasing action. The lasing occurs right at the center of spontaneous emission rather than the often reported redshifted wavelength. A spectroscopic ellipsometry analysis indicates that the gain of lasing action is provided by exciton transition. (C) 2011 Optical Society of America
SONOS memories with embedded silicon nanocrystals in nitride
(2008-07-01)
Liu, Mei-Chun
;
Chiang, Tsung-Yu
;
Kuo, Po-Yi
;
Chou, Ming-Hong
;
Wu, Yi-Hong
We have successfully demonstrated SONOS memories with embedded Si-NCs in silicon nitride. This new structure exhibits excellent characteristics in terms of larger memory windows and longer retention time compared to control devices. Using the same thickness 2.5 nm of the bottom tunneling oxide, we found that N(2)O is better than O(2) oxide. Retention property is improved when the thickness of N(2)O is increased to 3.0 nm.