Beta-Gallium Oxide Transistors for High Frequency Applications

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The objective of the proposed work is to design and demonstrate high frequency Beta-Gallium Oxide based transistors. Silicon based electronics is ubiquitous and provides excellent performance for many applications, but there still remain certain critical technology areas where other semiconductor materials, particularly wide band gap semiconductors, have properties that make them superior to silicon. Gallium Oxide is one such semiconductor whose intrinsic properties make it potentially superior for applications such as high frequency communications. However, to harness these properties for better performance, new device engineering (design and fabrication) techniques need to be developed. The proposed research project focuses on engineering of transistors based on this material that could enable high frequency electronics in a range that is higher than the typical wireless communication technology used currently. With the proliferation of networked intelligent devices and sensors throughout our environment, the need for high data rate communication is increasing at an unprecedented rate. Therefore, there is a significant need for high power density mm-wave amplifiers with high gain and efficiency. The development of Gallium Oxide-based high power mm-wave transistors proposed here could enable a new generation of such high data rate systems based on mm-wave and THz communications. A new course focused on wide band gap semiconductor devices will also be developed, whose course content will be offered free online. The main goal of this project is to determine the frequency and power limits for Gallium Oxide transistors in the mm-wave frequency range, and to design and demonstrate transistors with state-of-art device performance. While Gallium Oxide has higher breakdown field than other wide band gap semiconductors such as Gallium Nitride and Silicon Carbide, it has lower carrier mobility. In addition, the high field transport characteristics are relatively unknown. This project will lead to a vertically integrated investigation of the design, growth, fabrication, and characterization of highly scaled Gallium Oxide transistors. The project will lead to a better understanding of critical aspects of device engineering for Gallium Oxide devices, including epitaxial designs such as delta-doped transistors and heterostructures to enable scaled transistors with short gate lengths, understanding of low and high field electron transport in such scaled channels, control of dispersion caused by surface as well as buffer traps, and field management techniques (such as field plates and passivation) necessary to control field distributions in these transistors. The proposed project will therefore lay the foundation for a new generation of scaled transistors based on Gallium Oxide, and the scientific findings will impact not just high frequency transistors, but also other technologies such as power switching transistors.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.