Dr. Xinbo Zou
Electrical and Computer Engineering Department
Hong Kong University of Science and Technology
III-nitride (III-N) semiconductor materials present attractive characteristics for various energy-efficient optoelectronic and electronic applications, including light-emitting diodes (LEDs), lasers, rectifiers, transistors and so on. In particular, III-N grown on Si has received extensive research interest due to its great potential of realizing low-cost high-performance electronics.
This seminar will begin with a brief introduction of challenges in growing high quality GaN epilayers on Si, followed by recent technology development and performance analysis of GaN-based devices on Si. Several material and device engineering methods in improving power conversion efficiency of LEDs grown on Si will be presented. Using a cost-effective Cu/Sn/Cu bonding technique, the vertical-injection LEDs showed a wall-plug efficiency of over 20% after LED thin film transfer and surface texture. Furthermore, the LEDs on the Cu/Sn/Cu metal foil could be transplanted onto various flexible substrates, which has important implications for next generation flexible electronics and wearable electronics. The development of green and yellow LEDs with embedded SiO2 nanorods will also be discussed. Finally, new opportunities in developing GaN-based power devices will be discussed. Results on vertical p-i-n rectifiers using GaN-on-Si epilayers will be presented. The reverse bias leakage current mechanism will be explained as well as rectifiers’ breakdown ruggedness characteristics.