Sub-10 nm epitaxial graphene nanoribbon FETs

Abstract

Graphene is being investigated as a promising candidate for electronic devices. For digital electronic devices, a substantial bandgap is necessary. It is possible to open a bandgap in graphene by quantum confinement of the carriers in patterned graphene nanoribbons (GNRs); GNRs with width W nm have a bandgap Eg∼1.3/W eV [1]. This implies that sub-10 nm wide ribbons can enable room-temperature operation of GNRs as traditional semiconductors, but with ultimate vertical scaling, and still take advantage of high current drives. To date, GNRs have been fabricated from exfoliated graphene [2] and operated by back gates, or nanometer scale ribbons produced by ‘explosive’ methods [3] that are neither controlled nor reproducible. These methods are not suitable for large-area device fabrication. In this work, we report lithographically patterned GNRs on epitaxial graphene on SiC substrates. Specifically, we show the first top-gated GNR field-effect transistors (FETs) on epi-graphene substrates that exhibit the opening of a substantial energy bandgap (exceeding ∼0.15 eV at a ribbon width of 10 nm), respectable carrier mobility (700 – 800 cm2/Vs), high current modulation (10∶1 at 300 K), and high current carrying capacity (0.3 mA/µm at VDS = 1 V) at the same time. Both single GNR and GNR array devices are reported.