Prof. Won Il Park [Hanyang University, Korea]
Title: Epitaxial growth of 3-Dimensional Semiconductor Nanocrystals
Time: 10:00 - 10:40 AM, Friday, January 20, 2017
Place: Conference room 410, HPSTAR (Shanghai)
Host: Dr. Bin Chen
Abstract
There has been a substantial interest in direct synthesis/fabrication of finely controlled three-dimensional (3D) nanostructures. Despite the recent advances in 3D fabrication, however, epitaxial growth of finely controlled, single crystalline 3D nanostructures is still constrained. Here, we demonstrate step-by-step growth of hierarchical 3D architectures composed of single crystalline semiconductor nanocrystals, consisting of oxide and nitride semiconductor and graphene. To achieve their full benefits of the 3D structures, we first established a low-temperature solution-phase synthesis of hierarchical 3D architectures composed of single crystalline semiconductors. With systematic study on the axial growth rate in correlations with the diameter and interspacing of nanocrystals, we found the strong interactions among the neighboring nanocrystal arrays, producing three different types of height versus diameter relationships. Second, we performed the position and growth direction controlled multi-step synthesis to produce the single crystalline 3D architectures consisting of epitaxially merged ZnO constituent crystals. Similar to biomolecular additive, artificial additive of citrate ions interact preferentially with a top surface of crystals, thereby regulating the growth anisotropy, from predominantly vertical to lateral direction. Finally, we have demonstrated heteroepitaxial growth of GaN/InGaN multilayer on the 3D ZnO crystals, which were then implemented to fabricate unconventional, pressure sensitive electronics and 3D light emitting crystal arrays.
Biography of the Speaker:
Professional History
2013-present Associate Professor, Materials Science & Engineering, Hanyang University
2013-2014 Visiting Professor, Dept. of Chemistry, The University of Chicago
2007-2013 Assistant Professor, Materials Science & Engineering, Hanyang University
2005-2007 Postdoctoral Fellow, Chemistry (Charles M. Lieber), Harvard University
Education
Yonsei University Materials Science & Engineering B.S. 2000
POSTECH Materials Science & Engineering Ph.D. 2005
Harvard University Chemistry and Chemical Biology Postdoc 2005-2007
Selected Publications (during the past 5 years)
1. S. S. Kwon, J. Yi, W. W. Lee, J. H. Shin, S. H. Kim, S. H. Cho, S. W. Nam and W. I. Park*, “Reversible and Irreversible Responses of Defect-engineered Graphene-based Electrolyte-gated pH Sensors” ACS Applied Materials & Interfaces 8, 834 (2016)
2. F. Xia, S. Kwon, W. W. Lee, Z. Liu, S. Kim, T. Song, K. J. Choi, U. Paik* and W. I. Park*, “Graphene as an Interfacial Layer for Improving Cycling Performance of Si Nanowires in Lithium-Ion Batteries” Nano Letters 15, 6658 (2015)
3. J. M. Lee, Y.-S. No, S. W. Kim, H.-G. Park* and W. I. Park*, “Strong interactive growth behaviours in solution-phase synthesis of three-dimensional metal oxide nanostructures” Nature Communications 6, 6325, doi:10.1038/ncomms7325 (2015)
4. F. Xia, S. B. Kim, H. Cheng, J. M. Lee, T. Song, Y. Huang, J. A. Rogers, U. Paik* and W. I. Park*, “Facile Synthesis of Free-Standing Silicon Membranes with Three-Dimensional Nanoarchitecture for Anodes of Lithium Ion Batteries” Nano Letters 13, 3340 (2013)
5. J. Yi, D. H. Lee, W. W. Lee and W. I. Park*, “Direct Synthesis of Graphene Meshes and Semi-Permanent Electrical Doping” Journal of Physical Chemistry Letters 4, 2099 (2013)
6. D. H. Lee, J. Yi, J. M. Lee, S. J. Lee, Y.-J. Doh, H. Y. Jeong, Z. Lee*, U. Paik*, J. A. Rogers andW. I. Park*, “Engineering Electronic Properties of Graphene by Coupling with Si-Rich, Two-Dimensional Islands” ACS Nano 7, 301 (2013)
7. Y.-H. Kim, S.-H. Kwon, J. M. Lee, M.-S. Hwang, J.-H. Kang, W. I. Park* and H.-G. Park*, “Graphene-contact electrically driven microdisk lasers” Nature Communications 3, 1123, doi:10.1038/ncomms2137 (2012).
8. J. Yi, H. S. Jang, J. S. Lee* and W. I. Park*, “Bioinspired Morphogenesis of Highly Intricate and Symmetric Silica Nanostructures” Nano Letters 12, 3743 (2012)