Browsing by Author "Hsueh, Hsu-Hung"

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Chemical lift-off process for nitride LEDs from an Eco-GaN template using an AlN/strip-patterned-SiO2 sacrificial layer
(2017-03-01)
Horng, Ray-Hua
;
Hsueh, Hsu-Hung
;
Ou, Sin-Liang
;
Tsai, Chi-Tsung
;
Tsai, Tsung-Yen
In this research, a nitride light-emitting diode (LED) fabricated on an electroplated Cu substrate can be removed from a GaN/sapphire (Eco-GaN) template by conducting the chemical lift-off (CLO) process using an AlN/strip-patterned-SiO2 intermediate sacrificial layer. The regrowth GaN epilayer deposited on AlN/patterned SiO2/Eco-GaN can achieve a high crystal quality via the epitaxial lateral overgrowth process. To etch the patterned SiO2 and AlN layers, the HF and 80 degrees C-KOH solutions were used, respectively. Due to the use of low-temperature KOH solution, the GaN epilayer would suffer less damage during the CLO process, improving the reuse feasibility for the Eco-GaN template. Moreover, when the etching treatment was used for the AlN layer, a highly lateral etching rate of 0.5mmh(-1) was achieved. Compared to the conventional LED, the vertical-type LED/Cu substrate had a higher output power of 212mW (at 350mA). Based on our estimation, the output power of LED prepared on Cu substrate had an 86% improvement in comparison to that of conventional LED. Obviously, the good optoelectronic performance of the LED/Cu device can be obtained after performing the CLO process. Furthermore, the separated Eco-GaN template has high potential for reuse applications, indicating that this technique is helpful to the cost-effective LED fabrication.
Effect of Top-Region Area of Flat-Top Pyramid Patterned Sapphire Substrate on the Optoelectronic Performance of GaN-Based Light-Emitting Diodes
(2016-01-01)
Hsueh, Hsu-Hung
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Ou, Sin-Liang
;
Peng, Yu-Che
;
Cheng, Chiao-Yang
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Wuu, Dong-Sing
The flat-top pyramid patterned sapphire substrates (FTP-PSSs) have been prepared for the growth of GaN epilayers and the fabrication of lateral-type light-emitting diodes (LEDs) with an emission wavelength of approximately 470 nm. Three kinds of FTP-PSSs, which were denoted as FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C, respectively, were formed through the sequential wet etching processes. The diameters of circle areas on the top regions of these three FTP-PSSs were 1, 2, and 3 mu m, respectively. Based on the X-ray diffraction results, the full-width at half-maximum values of rocking curves at (002) plane for theGaN epilayers grown on conventional sapphire substrate (CSS), FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C were 412, 238, 346, and 357 arcsec, while these values at (102) plane were 593, 327, 352, and 372 arcsec, respectively. The SpeCLED-Ratro simulation results reveal that the LED prepared on FTP-PSS-A has the highest light extraction efficiency than that of the other devices. At an injection current of 350 mA, the output powers of LEDs fabricated on CSS, FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C were 157, 254, 241, and 233 mW, respectively. The results indicate that both the crystal quality of GaN epilayer and the light extraction of LED can be improved via the use of FTP-PSS, especially for the FTP-PSS-A.
Fabrication of nitride LEDs using chemical lift-off from a GaN/sapphire template
(2016)
Horng, Ray-Hua
;
Hsueh, Hsu-Hung
;
Ou, Sin-Liang
;
Wuu, Dong-Sing
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電子工程學系及電子研究所