Epitaxial Graphene on SiC for Ultra-high Frequency Transistors*

Electronic devices and systems operating at ultra-high frequencies have recently generated significant interest. Graphene is considered a promising candidate material for high-frequency electronics, due to its intrinsic low dimensionality, high carrier mobility and large carrier velocity. Field effect transistors made of exfoliated graphene flakes as the channel material have shown cut-off frequency (f$_{\mathrm{T}})$ above 400 GHz. However, the maximum oscillation frequency (f$_{\mathrm{max}})$ of graphene transistors, which sets the practical limit on useful circuit operation, to date have not exceeded 45 GHz. We report here record intrinsic f$_{\mathrm{max}}$ of 70 GHz, with f$_{\mathrm{T}}$ exceeding 100 GHz, for transistors based on epitaxial graphene on SiC. In addition to setting a new performance record for graphene technology, these epitaxial graphene transistors were fabricated using well-developed, robust, top-down processes compatible with a mass-production-compatible platform.