GaN Optoelectronic Devices

Prof Lee will introduce his research in wide bandgap semiconductor materials. GaN-based opto-electronic devices included GaN-based LEDs and GaN-based MOS-HEMT. The research about GaN-based LEDs included white light emitting diodes, current spreading of LEDs, and high extraction efficiency. White light can be obtained using monolithic carbon-implanted InGaN/GaN MQW LED structure. To mix the blue light and the generated yellow-green light, white emission can be obtained in the monolithic InGaN/GaN LEDs. Plasma is used to selectively treat the p-type GaN region underneath the bonding pad of the anode electrode of GaN-based LEDs to improve the current spreading of the LEDs. A film with nano-particles was deposited on transparent area of p-type GaN to improve the light extraction efficiency of GaN-based LEDs. The photoelectrochemical etching method was also used to etch and roughen the p-GaN surface to improve the light extraction efficiency.
GaN-based MOS-HEMT: A photoelectrochemical oxidation method was used to grow oxide films on n-GaN and n-AlGaN directly. The measured results of X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDX), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) showed that PEC oxidation method oxidized n-GaN and n-AlGaN successfully. I-V and photo-assisted C-V measurement proofed MOS diodes with gate dielectrics grown by PEC oxidation method have better electrical performances. We also fabricated AlGaN/GaN MOS-HEMTs using PEC method. According to measured DC and RF characteristics, it can be seen that PEC oxidation method can be expected as a promising method to fabricate MOS devices. In addition, Prof Lee will also introduce his research on ZnO nanowire and ZnO-based LEDs.

Ching-Ting Lee received his B.S. and M.S. in Electrical Engineering Department of the National Cheng-Kung University, Taiwan, in 1972 and 1974, respectively. He received Ph.D. degree in Electrical Engineering Department from the Carnegie-Mellon University in 1982. He worked on Chung Shan Institute of Science and Technology, before he joined the Institute of Optical Sciences, National Central University, Chung-Li, Taiwan, as a Professor in 1990. He works on National Cheng-Kung University as the dean of Electrical Engineering and Computer Science and the professor of the Institute of Microelectronics, Department of Electrical Engineering in 2003. His current research interests include GaN–based LEDs, GaN-based MOS-HEMTs, ZnO nanowire and ZnO-based LEDs, crystalline SiGe films and Si nanocluster, and electromagnetic filed electrooptical sensor using LiNbO3 Mach-Zehnder and antenna. His research activities have also involved in the research concerning semiconductor lasers, photodetectors and high-speed electronic devices, and their associated integration for electrooptical integrated circuits. He received the outstanding Research Professor Fellowship from the National Science Council, R.O.C. in 2000 and 2002. He also received the Optical Engineering Medal from Optical Engineering Society and Distinguish Electrical Engineering professor award from Chinese Institute of Electrical Engineering Society in 2003.