1. Remote Epitaxy of Gallium Nitride through Graphene Assistance - MOCVD
III−V materials, particularly Gallium Nitride (GaN), are used commercially in our life. High breakdown voltage, high luminous efficiency, and tunable bandgap are advantage of GaN. Based on that, Light emitting diode, Power device are fabricated by GaN. Until now, GaN-based devices have been developed so far, but GaN epitaxy is often limited by the strict need for lattice matching with substrate. This requirement not only determine the crystal quality for device performance, but also limit to its application in various fields. In our laboratory, to expand application with high-quality epitaxy, Remote Epitaxy of GaN with the two-dimensional (2D) graphene has been studied by metal organic chemical vapor deposition (MOCVD).
Remote Epitaxy is helped by 2D material which cannot completely screen the stronger potential field of substrate, which enables quasi-homoepitaxy as meaning of ‘remote’ despite its presence. The grown single-crystalline films can be released from the substrate covered with 2D graphene due to its weak van der Walls force and open up a new opportunity to application of GaN-based device with flexibility and transferability, especially such as high-integrated flexible LED display.
2. III-Nitride nanowire growth and applications - MBE
Fig. 1. SEM images of GaN nanowires grown by plasma-assisted molecular beam epitaxy.
(a) GaN nanowires grown on silicon substrate. (b) GaN nanowires grown on titanium coated quartz substrate.
A lattice-matching with substrates is essential for thin-film growth of III-Nitride materials. However, by growing the nanowire structure rather than the thin film, this restriction can be considerably reduced. We are researching on the growth of III-Nitride nanowires and applying them to devices such as light-emitting diodes (LEDs). In detail, we are studying the AlGaN nanowire growth for UV-LED and the growth on the hetero-substrates to combine III-nitride materials with other materials such as quartz.
3. Current project
Amano Center for Advanced LEDs
Sponsor: GIST Research Institute (GRI)
Project Leader: Hoe-Min Kwak
Development of GaN nanomembrane for flexible hetero-integration optoelectronic device applications
Sponsor: National Research Foundation of Korea(NRF)
Project Leader: Jun-Yeop Lee