Wafer-scale Epitaxial Graphene Growth on the Si-face of Hexagonal SiC (0001) for High Frequency Transistors

摘要

Up to two layers of epitaxial graphene have been grown on the Si-face oftwo-inch SiC wafers exhibiting room-temperature Hall mobilities up to 1800cm^2/Vs, measured from ungated, large, 160 micron x 200 micron Hall bars, andup to 4000 cm^2/Vs, from top-gated, small, 1 micron x 1.5 micron Hall bars. Thegrowth process involved a combination of a cleaning step of the SiC in aSi-containing gas, followed by an annealing step in Argon for epitaxialgraphene formation. The structure and morphology of this graphene has beencharacterized using AFM, HRTEM, and Raman spectroscopy. Furthermore, top-gatedradio frequency field effect transistors (RF-FETs) with a peak cutoff frequencyfT of 100 GHz for a gate length of 240 nm were fabricated using epitaxialgraphene grown on the Si face of SiC that exhibited Hall mobilities up to 1450cm^2/Vs from ungated Hall bars and 1575 cm^2/Vs from top-gated ones. This is byfar the highest cut-off frequency measured from any kind of graphene.