Browsing by Author "Liao, Wei-Chih"

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Improved crystal quality and performance of GaN-based light-emitting diodes by decreasing the slanted angle of patterned sapphire
(2010-02-01)
Cheng, Ji-Hao
;
Wu, YewChung Sermon
;
Liao, Wei-Chih
;
Lin, Bo-Wen
;
材料科學與工程學系
Periodic triangle pyramidal array patterned sapphire substrates (PSSs) with various slanted angles were fabricated by wet etching. It was found beside normal wurtzite GaN, zinc blende GaN was found on the sidewall surfaces of PSS. The crystal quality and performance of PSS-LEDs improved with decrease in slanted angle from 57.4 degrees to 31.6 degrees. This is because most of the growth of GaN was initiated from c-planes. As the growth time increased, GaN epilayers on the bottom c-plane covered these pyramids by lateral growth causing the threading dislocation to bend toward the pyramids.
Versatility of fluorene metabolite (phenol) in fluorene biodegradation by a sulfate reducing culture
(2011-06-01)
Kumar, Mathava
;
Liao, Wei-Chih
;
Tsai, Jen-Chieh
;
Lin, Jih-Gaw
;
環境工程研究所
Biodegradability of fluorene and the versatility of fluorene metabolite (i.e. phenol) in fluorene biodegradation by a sulfate-reducing enrichment culture were investigated. Batch experiments (with 5 mg l(-1) fluorene) were designed via the central composite design to examine the effects of sulfate (5-35 mM) and biomass (5-50 mg l(-1)) concentrations (variables) on fluorene degradation (response). The experimental results revealed that fluorene removal was more influenced by the biomass concentration than the sulfate concentration. The optimal sulfate and biomass concentrations for fluorene biodegradation (90% removal) were found to be 14.4 mM and 37.8 mg l(-1), respectively. Under the optimal conditions, a set of biodegradation experiments were repeated to evaluate both the biodegradability of fluorene metabolite and the potential effect of phenol accumulation on fluorene degradation. The outcomes indicated a slow phenol degradation rate, i.e. 0.02 mg l(-1) d(-1). Moreover, a small reduction in the fluorene biodegradation efficiency was observed in the presence and accumulation of phenol. However, this sulfate reducing culture is a valuable resource for the simultaneous degradation of fluorene and phenol. (C) 2011 Elsevier Ltd. All rights reserved.