Ultra-wide band gap materials for high frequency applications

Gallium Nitride electronics based on the AlGaN/GaN high electron mobility transistor structure is approaching intrinsic limits. Future mm-wave and THz technology requires highly efficient and linear amplifiers that can deliver high power density. This presentation will outline the potential and recent work of next-generation wide band gap transistors based on ultra-wide band gap semiconductors for high frequency applications. Detailed DC and high frequency 2-dimensional modeling of ultra-wide band gap semiconductor devices show that the predicted power density, gain, and efficiency of these devices have the potential to be better than cutting-edge GaN-based devices at mm-wave and THz frequencies. We will discuss the principal challenges for realization of these devices and outline the design and demonstration of advanced high Al-composition AlGaN based transistors, where researchers have used novel epitaxial designs to enable efficient injection and extraction of carriers. This has enabled the state-of-the-art current density and breakdown characteristics of AlGaN-channel devices to increase significantly in recent years.