The world is facing serious challenges in conserving energy resources and reducing carbon emissions as demand for energy consumption expands. The demand for electricity is expected to increase significantly with further electrification of our world driven by renewable energy usage, electrification of transportation, expansion of efficient electrical heating and cooling, expansion of information traffic, increased industrial motor usage, and new smart grid development. Advanced wide bandgap (WBG) semiconductor power electronics will play a critical role in all phases of the electricity life cycle including generation, distribution and consumption, and have the potential to improve electricity efficiency by 10-25%. Gallium Nitride (GaN) power devices offer a high performance solution in electric vehicles, motor drives, grid-tied renewable inverters, ultra-compact power supplies, and many other energy conversion systems. However, material defects in today's fabrication processes prevent full realization of this potential. This international collaboration project between the US, Republic of Ireland and Northern Ireland investigators will address the fundamental challenges on GaN material defects, reliability, and cost, and potentially has a large impact to the WBG power electronics industry.
The objective of the project is to explore high voltage vertical device architectures based on GaN nanowires, and advance the fundamental understanding of materials growth and defect mechanisms, electrical breakdown and transport properties to establish a viable nanotechnology building block for power electronics applications. The approach is to model, fabricate, and characterize high voltage Schottky barrier diodes, merged PiN Schottky diodes, and gate-all-around field effect transistors on nano-GaN materials grown with selective area metalorganic vapor phase epitaxy (MOVPE) on silicon substrates. The US-Ireland collaborative research project combines the MOVPE growth and nanofabrication capabilities at Tyndall National Institute in Ireland, the material analysis capabilities at Queen's University Belfast in Northern Ireland with the device modeling, design, and testing expertise at Illinois Institute of Technology. The intellectual merit of this research is to open up a new direction in reducing or eliminating dislocations and improving reliability of wide WBG power semiconductors, leading to novel high voltage GaN device architectures on a silicon platform. This is distinctly different from the mainstream lateral GaN device architectures based on heteroexpitaxial thin-films. The project will address fundamental and applied research related to nano- and micro-scale device design and modeling, nanoheteroexpitaxial materials growth and characterization, and device fabrication. It will advance the basic understanding of one-dimensional semiconductor epitaxial growth kinetics and the effects of facet surface states on carrier transport and device breakdown properties.
