▎ 摘　　要

The maximum oscillation frequency (f(max)) quantifies the practical upper bound for useful circuit operation. We report here an f(max) of 70 GHz in transistors using epitaxial graphene grown on the C-face of SiC. This is a significant improvement over Si-face epitaxial graphene used in the prior high-frequency transistor studies, exemplifying the superior electronics potential of C-face epitaxial graphene. Careful transistor design using a high kappa dielectric T-gate and self-aligned contacts further contributed to the record-breaking f(max).