To meet the growing demands of advanced electronic circuits, next-generation semiconductor devices must operate efficiently at higher power levels and switching frequencies, while remaining compact. Emerging ultra-wide band gap (UWBG) semiconductors like diamond, BN, AlN, and Ga2O3, face different challenges in overcoming the state-of-the-art GaN semiconductor device limits, including limited wafer sizes, doping difficulties, and thermal management constraints. Here, we analyze the emerging application and existing device trends, and present the results of our high-throughput computational screening of >1,300 semiconductors for high-frequency electronics. We find >250 new semiconductors with high Johnson and Baliga high-frequency figures of merit, and thermal conductivities, and discuss synthesis and doping of a few most promising candidates. This study lays the foundation for discovering new semiconductors that can push the boundaries of performance in applications ranging from EV chargers and solid-state transformers to sub-THz communications and advanced radar technologies.