ASCENT: Reducing greenhouse emissions with ultra-efficient High-Voltage Monolithic Bidirectional Transistors

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Increasing energy demands require an urgent need for efficient utilization of available electric power, and 80% of the total generated electric power is expected to flow through power electronics by 2030. With the rising electrification of the modern grid and transportation, ultra-efficient bidirectional power flow is fast becoming an emerging requirement. Bidirectional power flow can be witnessed in a grid (for example, solar energy from consumer to grid and from grid to consumer, consumer as storage and distribution element), electric car (for example, from car to grid and grid to car, car to another car, car as a source and consumer of electric power), industrial motor drives, solid-state transformers, data center power supplies, elevator drives, DC microgrids, energy storage, etc. All these applications drive the rapid expansion of power electronics across all forms of electrical power consumption and production; thus, it is critical that their construction is sustainable, compact, and they operate efficiently. However, incumbent circuit solutions as well as semiconductor devices that support bidirectional power flow result in large footprint, reduced efficiency, and low fault tolerance. This NSF proposal aims to take a materials, devices, and circuit co-design approach to tackle both semiconductor device and circuit challenges simultaneously. We propose to utilize circuit architectures such as matrix converters (MCs) and current source inverters (CSIs) with suitably designed semiconductor transistors, i.e., bidirectional transistors, to present a cohesive solution. Bidirectional transistors have the capability to block voltage and conduct current in both directions. Through our multi-abstraction level collaborative research, novel material and bidirectional device synthesis and fabrication steps will be developed, device and circuit level understanding of bidirectional transistor operation will be gained and the performance of these devices in MC and CSI inverter topologies will be demonstrated and benchmarked. This research effort will be complemented with efforts for education and workforce development activities as well as broadening participation amongst K-12, pre-college, and college students. The key objective of this proposal is to leverage wide bandgap materials (WBG) and ultra-wide-bandgap (UWBG) materials to develop ultra-efficient, high-voltage monolithic bidirectional transistor (MBDT) to be utilized in efficient bidirectional power flow enabling circuits. This project will focus on these research goals. 1) Demonstration of the first UWBG based monolithic bidirectional transistors (MBDT). 2) Enhancing the performance of GaN Monolithic Bidirectional Transistor and manufacturability simultaneously by material-device co-design. 3) Development of a unique high-conductivity multi-channel UWBG (AlGaN) material development which can lead to < 10x conduction losses compared to incumbent solutions. 4) Develop comprehensive understanding of physical phenomenon electron-trapping, hysteresis, breakdown mechanisms, current collapse, thermal limits, robustness, and reliability in monolithic bidirectional transistors. 5) Demonstration of converter topologies and benchmarking efficiency with the introduction of monolithic bidirectional transistors compared to incumbent solutions. Our workforce education, training, and development efforts will include fostering student-industry collaboration by facilitating internship opportunities, lunch seminar networking, and curriculum redesign. Additionally, we will work with industry and local Madison area technical colleges to design courses to meet rising technician and operator needs. We will broaden participation by performing outreach activities for pre-college students and increase awareness at the K-12 level on smart energy choices with a new activity at the Wisconsin Science Festival and Engineering Expo. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.