Ultrafast carrier dynamics of semi-polar (11-20) InGaN/GaN core-shell quantum wells grown on m-plane GaN nanowires

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Building 9, Level 2, Hall 1, Room 2322
Prof. San-Wan Ryu, Chonnam National University


GaN-based light-emitting diodes (LEDs) on sapphire are known to exhibit high efficiency and long lifetime. In order to fabricate the cost-effective LEDs on larger scale, the most efficient approach is the growth of scalable and high crystal quality GaN nanowires on amorphous substrate, preferably glass. We have demonstrated the growth of GaN nanowire-based LEDs using metal-organic chemical vapor deposition on an amorphous glass substrate. Additionally, the InGaN/GaN multiple quantum well shells are conformally grown on semipolar (1122) growth facet of m-axial GaN core nanowires and resulted in reduced quantum confined Stark effect. The photoluminescence spectroscopy of the GaN core nanowire-ensemble reveals a very high crystal quality due to the dominant emission from the band-to-band transition and absence of a characteristic yellow luminescence. Furthermore, the temperature-dependent PL of the nanowire ensemble exhibits a very high internal quantum efficiency of 76.1%. Therefore, the ultrashort radiative lifetime of the carriers was in the range between 19 ps and 54 ps. These results emphasize the potential of our approach to grow high-crystal quality GaN nanowires on amorphous substrates for large scale production and various optical applications such as LEDs, solar cells, and photodetectors.

Brief Biography

Sang-Wan Ryu received the B.S., M.S., and Ph.D. degrees in physics from Seoul National University, Seoul, Korea, in 1992, 1994, and 1998, respectively. After graduation, he joined the University of Southern California, Los Angeles, in a post-doctoral position till 2000 where he worked on a long-wavelength VCSEL. During 2000-2004, he worked with the Electronics and Telecommunication Research Institute, Taejon, Korea, and researched on optical devices for fiber communication. Then he moved to the Department of Physics, Chonnam National University, Gwangju, Korea, in 2004, and has been continuing his research on growth and characterization of novel semiconductor materials, nano-fabrication, and the applications for optical, electrical, and energy devices.

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