CHANG-HEE CHO

 

Postdoctoral Scholar

University of Pennsylvania, Department of Materials Science and Engineering

3231 Walnut Street, Philadelphia, PA 19104-6202, USA

E-mail: changhee@seas.upenn.edu, Lab: http://agarwal.seas.upenn.edu/

RESEARCH INTERESTS

1.  Fundamental properties of semiconductor nanostructures such as nanocrystals and nanowires.

2.  Plasmonic and photonic engineering of optical properties in semiconductors.

3.  Novel optoelectronic devices including light-emitting diodes, lasers, and solar cells.

 

ACADEMIC TRAINING

University of Pennsylvania, Philadelphia, PA, USA

Postdoctoral Scholar, Materials Science and Engineering (Sep. 2009 ~ Present)

Advisor: Prof. Ritesh Agarwal

 

Gwangju Institute of Science and Technology, Gwangju, Korea

Ph. D. Materials Science and Engineering (Aug. 2009)

Advisor: Prof. Seong-Ju Park

 

Gwangju Institute of Science and Technology, Gwangju, Korea

M. S. Materials Science and Engineering (Feb. 2004)

Advisor: Prof. Seong-Ju Park

 

Kyung Hee University, Seoul, Korea

B. S. Physics (Feb. 2002)

 

PUBLICATIONS (Refereed Journals)

21.  Chang-Hee Cho, C. O. Aspetti, M. E. Turk, J. M. Kikkawa, S. W. Nam, and R. Agarwal, ¡°Tailoring hot-exciton emission and lifetimes in semiconducting nanowires via whispering-gallery nanocavity plasmons¡±, Nature Materials 10, 669 (2011). [link]

20.  L. K. van Vugt, B. Piccione, Chang-Hee Cho, P. Nukala, and R. Agarwal, ¡°One-dimensional polaritons with size-tunable and enhanced coupling strengths in semiconductor nanowires¡±, Proc. Natl. Acad. Sci. USA 108, 10050 (2011). [link]

19.  L. K. van Vugt, B. Piccione, Chang-Hee Cho, C. Aspetti, A. D. Wirshba and R. Agarwal, ¡°Variable temperature spectroscopy of as-grown and passivated CdS nanowire optical waveguide cavities¡±, Journal of Physical Chemistry A 115, 3827 (2011). [link]

18.  Chang-Hee Cho, B. H. Kim, S. K. Kim, and S. J. Park, ¡°Characterization of electronic structure of silicon nanocrystals in silicon nitride by capacitance spectroscopy¡±, Applied Physics Letters 96, 223110 (2010). [link]

17.  Chang-Hee Cho, S. K. Kim, B. H. Kim, and S. J. Park, ¡°Strong size-dependent characteristics of carrier injection in quantum-confined silicon nanocrystals¡±, Applied Physics Letters 95, 243108 (2009). [link]

16.  B. H. Kim, R. F. Davis, Chang-Hee Cho, and S. J. Park, ¡°Effect of injection current density on electroluminescence in silicon quantum dot light-emitting diodes¡±, Applied Physics Letters 95, 153103 (2009). [link]

15.  B. H. Kim, R. F. Davis, Chang-Hee Cho, S. J. Park, C. Huh, and G. Y. Sung, ¡°Enhancement of electrical and optical properties of silicon quantum dot light-emitting diodes with ZnO doping layer¡±, Japanese Journal of Applied Physics 48, 105004 (2009). [link]

14.  S. K. Kim, Chang-Hee Cho, B. H. Kim, S. J. Park, and J. W. Lee, ¡°Electrical and optical characteristics of silicon nanocrystal solar cells¡±, Applied Physics Letters 95, 143120 (2009). [link]

13.  B. H. Kim, R. F. Davis, Chang-Hee Cho, and S. J. Park, ¡°Enhanced performance of silicon quantum dot light-emitting diodes grown on nanoroughened silicon substrate¡±, Applied Physics Letters 95, 073113 (2009). [link]

12.  S. K. Kim, Chang-Hee Cho, B. H. Kim, Y. S. Choi, S. J. Park, K. Lee, and S. Im, ¡°The effect of localized surface plasmon on the photocurrent of silicon nanocrystal photodetectors¡±, Applied Physics Letters 94, 183108 (2009). [link]

11.  T. Y. Park, Chang-Hee Cho, I. K. Park, and S. J. Park, ¡°Improved leakage current, output power, and electrostatic discharge characteristics of GaN LEDs by chemical etching¡±, Electrochemical and Solid-State Letters 12, D3-D6 (2009). [link]

10. S. K. Kim, B. H. Kim, Chang-Hee Cho, and S. J. Park, ¡°Size-dependent photocurrent of photodetectors with silicon nanocrystals¡±, Applied Physics Letters 94, 183106 (2009). [link]

9. B. H. Kim, Chang-Hee Cho, J. S. Mun, M. K. Kwon, T. Y. Park, J. S. Kim, C. C. Byeon, J. Lee, and S. J. Park, ¡°Enhancement of the external quantum efficiency of a silicon quantum dot light-emitting diode by localized surface plasmons¡±, Advanced Materials 20, 3100-3104 (2008). [link]

8. I. K. Park, M. K. Kwon, C. Y. Cho, J. Y. Kim, Chang-Hee Cho, and S. J. Park, ¡°Effect of InGaN quantum dot size on the recombination process in light-emitting diodes¡±, Applied Physics Letters 92, 253105 (2008). [link]

7. B. H. Kim, Chang-Hee Cho, S. J. Park, N. M. Park, and G. Y. Sung, ¡°Ni/Au contacts to silicon quantum dot light-emitting diodes for the enhancement of carrier injection and light extraction efficiency¡±, Applied Physics Letters 89, 063509 (2006). [link]

6. Chang-Hee Cho, B. H. Kim, and S. J. Park, ¡°Room-temperature Coulomb blockade effect in silicon quantum dots in silicon nitride films¡±, Applied Physics Letters 89, 013116 (2006). [link]

5. T. W. Kim, Chang-Hee Cho, B. H. Kim, and S. J. Park, ¡°Quantum confinement effect in crystalline silicon quantum dots in silicon nitride grown using SiH4 and NH3¡±, Applied Physics Letters 88, 123102 (2006). [link]

4. D. Lee, S. Heo, Chang-Hee Cho, G. H. Buh, T. S. Park, J. Yoo, Y. Shin, and H. Hwang, ¡°Electrical characteristics of ultrashallow p+/n junction formed by BF3 plasma doping and two-step annealing process¡±, Electrochemical and Solid-State Letters 9, G121-G123 (2006). [link]

3. D. Lee, S. Baek, S. Heo, Chang-Hee Cho, G. Buh, T. S. Park, Y. Shin, and H. Hwang, ¡°Ultrashallow p+/n junction prepared by BF3 plasma doping and KrF excimer laser annealing¡±, Electrochemical and Solid-State Letters 9, G19-G21 (2006). [link]

2. Chang-Hee Cho, B. H. Kim, T. W. Kim, N. M. Park, G. Y. Sung, and S. J. Park, ¡°Effect of hydrogen passivation on charge storage in silicon quantum dots embedded in silicon nitride film¡±, Applied Physics Letters 86, 143107 (2005). [link]

1. B. H. Kim, Chang-Hee Cho, T. W. Kim, N. M. Park, G. Y. Sung, and S. J. Park, ¡°Photoluminescence of silicon quantum dots in silicon nitride grown by NH3 and SiH4¡±, Applied Physics Letters 86, 091908 (2005). [link]

 

PATENTS

1.  B. H. Kim, Chang-Hee Cho, and S. J. Park, ¡°Silicon quantum dot light-emitting diode and fabricating method thereof¡±, Korea Patent, 100899940, 2009/05/21.

2.  Chang-Hee Cho, J. S. Mun, B. H. Kim, and S. J. Park, ¡°Non-volatile Memory Device of using Semiconductor Quantum Dot¡±, Korea Patent, 100884887, 2009/02/13.

3.  R. Agarwal, Chang-Hee Cho, and C. O. Aspetti, ¡°Emission in nanowires via nanocavity plasmons¡±, US Patent Application No. 61/562,685 (2011/11/22).

4.  J. K. Nam, S. C. Park, Y. J. Park, Chang-Hee Cho, S. K. Kim, and S. J. Park, ¡°Silicon quantum dot photodetector device¡±, (Korea, pending), 08-0028497.

5.  J. W. Kang, M. S. Oh, Chang-Hee Cho, T. Y. Park, and S. J. Park, ¡°Light emitting diode including magnetic structure and light emitting diode package including magnetic structure¡±, (Korea, pending), 09-0011324.

6.  D. Y. Lee, S. J. Park, M. K. Kwon, C. Y. Cho, Chang-Hee Cho, Y. C. Kim, S. B. Seo, M. G. Cheong, and, D. J. Kim, ¡°Semiconductor Light Emitting Device¡±, US Patent Application No. 12/628,467, Publication No. US 2010/0181588 A1 (2010/07/22).

7.  D. Y. Lee, S. J. Park, M. K. Kwon, C. Y. Cho, Chang-Hee Cho, Y. C. Kim, S. B. Seo, M. G. Cheong, and, D. J. Kim, ¡°Semiconductor Light Emitting Device¡±, (Korea, pending), 09-0004547.

 

PRESENTATION (Selected)

1.  Chang-Hee Cho, C. Aspetti, M. E. Turk, J. M. Kikkawa, S. W. Nam, and R. Agarwal, ¡°Tailoring hot-excitonic emission in semiconductor nanowires by controlling lifetimes with nanocavity plasmons¡±, MRS Fall Meeting, Boston, USA, Nov. 28 – Dec. 2, 2011.

2.  Chang-Hee Cho, C. Aspetti, and R. Agarwal, ¡°Observation of hot excitonic emission in single CdS nanowires integrated with a plasmon nanocavity¡±, MRS Fall Meeting, Boston, USA, Nov. 29 – Dec. 3, 2010.

3.  Chang-Hee Cho and S. J. Park, ¡°Si quantum dots for optoelectronic applications¡±, Seoul National University Workshop on Silicon Photonics for Optical Interconnect, Seoul, Korea, 22 October, 2008 (Invited).

4.  Chang-Hee Cho, B. H. Kim, S. K. Kim, J. S. Mun, and S. J. Park, ¡°Quantum confinement effect on nonvolatile silicon nanocrystal memory characteristics¡±, Korean Vacuum Society, Suwon, Korea, 14-15 February, 2008.

5.  Chang-Hee Cho, B. H. Kim, and S. J. Park, ¡°Room-temperature Coulomb blockade effect in silicon quantum dots in silicon nitride film¡±, MRS Spring Meeting, San Francisco, USA, 17-21 April, 2006.

6.  Chang-Hee Cho, B. H. Kim, and S. J. Park, ¡°Effect of hydrogen on retention characteristics in nonvolatile memory with silicon quantum dots embedded in silicon nitride film¡±, IEEE Silicon Nanoelectronics Workshop, Kyoto, Japan, 12-13 June, 2005.

 

RESEARCH PROJECTS (in Korea)                                                              

1.  ¡°Doping of silicon quantum dots for quantum dot tandem solar cells¡± funded by Samsung Electronics.

2.  ¡°Silicon quantum dot photodetector for advanced image sensor¡± funded by Samsung Electronics.

3.  ¡°Gallium nitride quantum dot UV single photon source¡± funded by US Air Force Office of Scientific Research.

4.  ¡°Development of highly efficient silicon quantum dot LED¡± funded by ETRI.

5.  ¡°Formation of silicon quantum dots for nanoelectronic device applications¡± funded by KRISS.

6.  ¡°Development of nanophase control technology for white light source¡± funded by National Research Laboratory Program.

 

TEACHING EXPERIENCE

Teaching Assistant in Gwangju Institute of Science and Technology:

¡°Thin Film Technology¡± for graduate students, Spring semester, 2006.

¡°Physical Chemistry of Solid Surface¡± for graduate students, Fall semester, 2006.

 

TECHNICAL SKILLS

- Growth and Device Fabrication: Chemical and Physical Vapor Deposition, Inductively Coupled Plasma etcher, UV Photolithography, Rapid Thermal Annealing, *Experience in fabrication & characterization of semiconductor nanocrystal and nanowire based devices such as nanocrystal LEDs, nanocrystal nonvolatile memories, nanowire transistors, etc.

- Material Analysis Techniques: Photoluminescence and Electroluminescence spectroscopy, Electrical characterization (Current-Voltage and Capacitance-Voltage), UV-Vis, Raman, and IR spectroscopies, Scanning Electron Microscope with Focused Ion Beam, X-ray Diffraction Spectroscopy, Atomic Force Microscopy, etc.

- Computer Techniques: Microcal Origin statistical programs, Rsoft Photonics CAD, COMSOL Multiphysics, Lumerical FDTD, etc.

 

PROFESSIONAL ACTIVITY                                                            

- Journal Reviewer for ¡®Optics Express¡¯, ¡®IEEE Transactions on Nanotechnology¡¯, and ¡®Solid State Communications¡¯.

- Member of Material Research Society

 

(Last Updated: Feb. 28, 2012)