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Hsueh H.-H.,National Chung Hsing University | Ou S.-L.,National Chung Hsing University | Cheng C.-Y.,Wafer Works Optronics Corporation | Wuu D.-S.,National Chung Hsing University | And 2 more authors.
International Journal of Photoenergy | Year: 2014

InGaN light-emitting diodes (LEDs) were fabricated on cone-shaped patterned sapphire substrates (PSSs) by using low-pressure metalorganic chemical vapor deposition. To enhance the crystal quality of the GaN epilayer and the optoelectronic performance of the LED device, the top-tip cone shapes of the PSSs were further modified using wet etching. Through the wet etching treatment, some dry-etched induced damage on the substrate surface formed in the PSS fabrication process can be removed to achieve a high epilayer quality. In comparison to the LEDs prepared on the conventional sapphire substrate (CSS) and cone-shaped PSS without wet etching, the LED grown on the cone-shaped PSS by performing wet etching for 3 min exhibited 55% and 10% improvements in the light output power (at 350 mA), respectively. This implies that the modification of cone-shaped PSSs possesses high potential for LED applications. © 2014 Hsu-Hung Hsueh et al. Source


Huang C.-Y.,National Taitung University | Cheng C.-Y.,Wafer Works Optronics Corporation | Su Y.-K.,National Cheng Kung University | Fang J.C.-L.,Wafer Works Optronics Corporation
World Academy of Science, Engineering and Technology | Year: 2011

ZnO nanostructures including nanowires, nanorods, and nanoneedles were successfully deposited on GaAs substrates, respectively, by simple two-step chemical method for the first time. A ZnO seed layer was firstly pre-coated on the O2-plasma treated substrate by sol-gel process, followed by the nucleation of ZnO nanostructures through hydrothermal synthesis. Nanostructures with different average diameter (15-250 nm), length (0.9-1.8 μm), density (0.9-16×109 cm-2) were obtained via adjusting the growth time and concentration of precursors. From the reflectivity spectra, we concluded ordered and taper nanostructures were preferential for photovoltaic applications. ZnO nanoneedles with an average diameter of 106 nm, a moderate length of 2.4 μm, and the density of 7.2×109 cm-2 could be synthesized in the concentration of 0.04 M for 18 h. Integrated with the nanoneedle array, the power conversion efficiency of single junction solar cell was increased from 7.3 to 12.2%, corresponding to a 67% improvement. Source


Huang C.-Y.,National Taitung University | Wu T.-H.,National Cheng Kung University | Cheng C.-Y.,National Cheng Kung University | Cheng C.-Y.,Wafer Works Optronics Corporation | Su Y.-K.,National Cheng Kung University
Journal of Nanoparticle Research | Year: 2012

ZnO nanostructures, including nanowires, nanorods, and nanoneedles, have been deposited on GaAs substrates by the two-step chemical bath synthesis. It was demonstrated that the O 2-plasma treatment of GaAs substrates prior to the sol-gel deposition of seed layers was essential to conformally grow the nanostructures instead of 2D ZnO bunches and grains on the seed layers. Via adjusting the growth time and concentration of precursors, nanostructures with different average diameter (26-225 nm), length (0.98-2.29 μm), and density (1.9-15.3 × 10 9 cm -2) can be obtained. To the best of our knowledge, this is the first demonstration of ZnO nanostructure arrays grown on GaAs substrates by the two-step chemical bath synthesis. As an anti-reflection layer on GaAs-based solar cells, the array of ZnO nanoneedles with an average diameter of 125 nm, a moderate length of 2.29 μm, and the distribution density of 9.8 × 10 9 cm -2 has increased the power conversion efficiency from 7.3 to 12.2 %, corresponding to a 67 % improvement. © 2012 Springer Science+Business Media B.V. Source


Horng R.-H.,National Chung Hsing University | Horng R.-H.,National Cheng Kung University | Hsueh H.-H.,National Chung Hsing University | Ou S.-L.,National Chung Hsing University | And 2 more authors.
2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013 | Year: 2013

In this study, GaN-based light emitting diodes (LEDs) were prepared on the cone-shaped patterned sapphire substrates (PSSs) by metal-organic chemical vapor deposition. To improve the epilayer quality and device performance of LEDs, the PSSs were further wet etched to form the modified top-tip cone shapes. With increasing the wet etching time to 3 min, the LED grown on the cone-shaped PSS has 53% and 8% enhancement in light output (@ 20 mA) as compared with that on conventional sapphire substrate (CSS) and the cone-shaped PSS without wet etching, respectively. © 2013 IEEE. Source


Hsueh H.-H.,National Chung Hsing University | Ou S.-L.,National Chung Hsing University | Cheng C.-Y.,Wafer Works Optronics Corporation | Wuu D.-S.,National Chung Hsing University | And 2 more authors.
ECS Transactions | Year: 2013

The GaN-based light emitting diodes (LEDs) were grown on the cone-shaped patterned sapphire substrates (PSSs) by metal-organic chemical vapor deposition. To enhance the epilayer quality and optoelectronic performance of LEDs, the PSSs were further wet etched to form the modified top-tip cone shapes. After the wet etching process, some dry-etched induced damage on sapphire surface generated in the PSS fabrication process could be removed, leading to a higher crystal quality in epilayer and better device performance. As the wet etching time was increased to 3 min, the LED grown on the cone-shaped PSS had 53% and 8% improvement in light output (@ 20 mA) compared to that on conventional sapphire substrate (CSS) and the cone-shaped PSS without wet etching, respectively. It indicates that the technique of the modification in PSS shape has a high potential in LEDs application. © The Electrochemical Society. Source

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