Dr. Chu-Young Cho Profile

Dr. Chu-Young Cho

at Korea Advanced Nano Fab Center

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Author

Publications (3)

Proceedings Article | 18 March 2013 Paper

Engineering future light emitting diodes and photovoltaics with inexpensive materials: Integrating ZnO and Si into GaN-based devices

C. Bayram, K. T. Shiu, Y. Zhu, C. W. Cheng, D. Sadana, F. H. Teherani, D. Rogers, V. Sandana, P. Bove, Y. Zhang, S. Gautier, C.-Y. Cho, E. Cicek, Z. Vashaei, R. McClintock, M. Razeghi

Proceedings Volume 8626, 86260L (2013) https://doi.org/10.1117/12.2009999

KEYWORDS: Gallium nitride, Silicon, Zinc oxide, Light emitting diodes, Indium gallium nitride, Crystals, Photovoltaics, Sapphire, Indium, Metalorganic chemical vapor deposition

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Indium Gallium Nitride (InGaN) based PV have the best fit to the solar spectrum of any alloy system and emerging LED lighting based on InGaN technology and has the potential to reduce energy consumption by nearly one half while enabling significant carbon emission reduction. However, getting the maximum benefit from GaN diode -based PV and LEDs will require wide-scale adoption. A key bottleneck for this is the device cost, which is currently dominated by the substrate (i.e. sapphire) and the epitaxy (i.e. GaN). This work investigates two schemes for reducing such costs. First, we investigated the integration of Zinc Oxide (ZnO) in InGaN-based diodes. (Successful growth of GaN on ZnO template layers (on sapphire) was illustrated. These templates can then be used as sacrificial release layers for chemical lift-off. Such an approach provides an alternative to laser lift-off for the transfer of GaN to substrates with a superior cost-performance profile, plus an added advantage of reclaiming the expensive single-crystal sapphire. It was also illustrated that substitution of low temperature n-type ZnO for n-GaN layers can combat indium leakage from InGaN quantum well active layers in inverted p-n junction structures. The ZnO overlayers can also double as transparent contacts with a nanostructured surface which enhances light in/out coupling. Thus ZnO was confirmed to be an effective GaN substitute which offers added flexibility in device design and can be used in order to simultaneously reduce the epitaxial cost and boost the device performance. Second, we investigated the use of GaN templates on patterned Silicon (100) substrates for reduced substrate cost LED applications. Controlled local metal organic chemical vapor deposition epitaxy of cubic phase GaN with on-axis Si(100) substrates was illustrated. Scanning electron microscopy and transmission electron microscopy techniques were used to investigate uniformity and examine the defect structure in the GaN. Our results suggest that groove structures are very promising for controlled local epitaxy of cubic phase GaN. Overall, it is concluded that there are significant opportunities for cost reduction in novel hybrid diodes based on ZnO-InGaN-Si hybridization.

Proceedings Article | 2 September 2008 Paper

Phosphor-free white light-emitting diode using InGaN/GaN multiple quantum wells grown on microfacets

Chu-young Cho, Il-Kyu Park, Min-Ki Kwon, Ja-Yeon Kim, Seong-Ju Park, Dong Ryul Jung, Kwang Woo Kwon

Proceedings Volume 7058, 70580N (2008) https://doi.org/10.1117/12.794575

KEYWORDS: Light emitting diodes, Gallium nitride, Electroluminescence, Quantum wells, Scanning electron microscopy, Indium gallium nitride, Luminescence, LED displays, LED backlight, Sapphire

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Proceedings Article | 2 September 2008 Paper

Effect of PdZn film on the performance of green light-emitting diodes

Ja-Yeon Kim, Min-Ki Kwon, Chu Young Cho, Sang-Jun Lee, Seong-Ju Park, Sunwoon Kim, Je Won Kim, Yong Chun Kim

Proceedings Volume 7058, 70580I (2008) https://doi.org/10.1117/12.794535

KEYWORDS: Green light emitting diodes, Gallium nitride, Hydrogen, Annealing, Light emitting diodes, Zinc, Indium, Palladium, Magnesium, Nickel

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