The III-Nitride material system has technological applications ranging from solid state lighting to high frequency/high power electronics. Availability of efficient interband tunnel junctions could enable devices such as multiple active region emitters, efficient UV emitters, and multi-junction solar cells. However, the large band gap of GaN poses severe challenges in achieving low resistance tunnel junctions. In this talk, we show how polarization and heterostructure engineering can be used to create large band-bending over nanoscale lengths to enhance tunneling. Our work has led to the state-of-the-art low tunneling specific resistance in III-nitrides. We will also present our work on GdN nanoisland-based tunnel junctions that could provide additional flexibility in device design. Investigations into band alignment of GaN/GdN heterojunction, current work on integrating these tunnel junctions in commercial LEDs, and future prospects of such devices will also be presented.
Sriram Krishnamoorthy is a final year PhD student in the Electrical and Computer Engineering department at The Ohio State University. He received his Bachelors of Engineering degree in Electrical Engineering and integrated Master of Science degree in Physics from Birla Institute of Technology & Science, Pilani in 2009. Since October 2009, he has been working towards his PhD with Prof. Siddharth Rajan on MBE growth, fabrication and characterization of III-nitride tunnel junction devices. His research interests include epitaxy, layered materials synthesis and devices, and wide band gap devices.