Browsing by Author "Chang, Sheng-Chieh"

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Growth of GaN on Patterned Sapphire Substrate with High-Index Facets
(2015-01-01)
Chang, Sheng-Chieh
;
Chen, Chien-Chih
;
Chang, Tsu-Chi
;
Lin, Kun-Lin
;
Lu, Tien-Chang
Periodic pyramidal array patterned sapphire substrate (PSS) with various inclined facets was fabricated by wet etching. It was found that {3 (4) over bar 17}, {4 (1) over bar(3) over bar 18}, and {12 (3) over bar5} facets are exposed on the PSS structure after etching. GaN grown on the PSS by metal-organic chemical vapor deposition was found to have a semi-polar orientation by structural characterization with scanning and transmission electron microscopy. Also, the results show that GaN is mainly grown on the {12 (3) over bar5} sapphire facet with the orientation relationship between GaN and sapphire as(01 (1) over bar(4) over bar)(GaN) // (3 (3) over bar0 (6) over bar)(sapphire) and [02 (2) over bar1](GaN) // [11 (2) over bar0](sapphire), and the dislocation density in the grown GaN decreased with thickness. In addition, photoluminescence and catholuminescence measurements show only strong near-band-edge emission from the semi-polar GaN on the {12 (3) over bar5} sapphire facet. (C) 2015 The Electrochemical Society. All rights reserved.
Reduced Residual Stress and Enhanced Performance of GaN-Based LEDs Prepared by Liquid Phase Deposition Silicon Oxide-Nano Patterned Sapphire Substrate
(2014-01-01)
Chang, Sheng-Chieh
;
Hsieh, Cheng-Yu
;
Lin, Bo-Wen
;
Cho, Hsin-Ju
;
Hsu, Wen-Ching
A simple liquid phase deposition (LPD) method was used to introduce nano SiO2 on sapphire substrates to fabricate nano-patterned sapphire substrates with top oxide layers (MNPSS). The X-ray diffraction (XRD) rocking curves and etching pit density (EPD) analyses show that the quality of MNPSS-GaN was better than that of GaN grown on flat sapphire substrates (FLAT-GaN). The photoluminescence (PL) spectrums showed a blueshift of MNPSS-GaN peak position compared with FLAT-GaN. The analyses of XRD reciprocal space map (RSM) revealed that this shift was caused by the residual stress. (C) 2014 The Electrochemical Society. All rights reserved.