Towards Nanoscale Gallium Nitride Electronics

Advanced nanofabrication techniques and the new materials available today enable us to design and realize electron devices with higher performance and more functionality than ever before. To illustrate this, I will describe our recent work on the relatively unexplored N-polar crystal orientation of Gallium Nitride (GaN). Unique nanometer-scale polarization and heterostructure designs using N-polar GaN and its alloys make it optimal for many applications including highly scaled high-speed transistors for microwave and digital applications, energy-efficient power switching devices for power supplies and motor drives, and sensors. I will discuss issues related to molecular beam epitaxy growth and device design and development of N-polar AlGaN/GaN field-effect transistors (FETs). Using a broad set of DC, pulsed, and RF measurement techniques, and by applying device physics and heterostructure design, we eliminated the DC-RF dispersion and leakage issues in these devices. The improvements in device design led to excellent microwave power performance comparable to state-of-art Ga-polar AlGaN/GaN transistors. The successful combination of material and device development has made N-polar GaN a viable technology for highly scaled devices and provides a framework for future high-performance and novel device research based on nanoscale N-polar GaN technology.
Siddharth Rajan received undergraduate degrees in Physics and Electrical Engineering from Birla Institute of Technology and Science, Pilani,
India in 2001, and M.S. and Ph.D. degrees in Electrical and Computer Engineering from University of California, Santa Barbara in 2006. He is currently employed as project scientist at University of California, Santa Barbara. He has contributed to the growth, physics, and
characterization of high-performance and novel Gallium Nitride-based devices. His research interests include nanoscale semiconductor devices and physics, molecular beam epitaxy, and the application of semiconductors to biological systems. Siddharth Rajan received the JNC-ASR Summer Fellowship in 2000 and the CNID Fellowship in 2004, and was a recepient of the 2005 Electronic Materials Conference Best Paper Award. He has co-authored 35 journal and conference publications.