UHV Growth of Graphene on SiC

We report graphene growth on Si- and C-face semi-insulating 6H SiC in UHV by thermal Si desorption /reconstruction of the remaining C. The SiC was etched in H$_{2}$ up to 1580 \r{ }C to smooth the surface. XPS shows the H$_{2}$-etched surfaces are covered by an oxide which desorbs at 1000 \r{ }C, resulting in a surface containing excess Si. At 1300 \r{ }C, the surface becomes stoichiometric in Si and C and a $\surd $3 x $\surd $3 R30 LEED pattern is observed. At 1350 \r{ }C, we observe a 6$\surd $3 x 6$\surd $3 R30 LEED pattern develop when graphene has formed, and a 1x1 LEED pattern for graphite films formed at temperatures greater than 1400 \r{ }C. Graphene layers were grown under a variety of temperatures and conditions and characterized using XPS, LEED, AFM, Raman spectroscopy, and Hall effect. Top-gated FETs were fabricated with a wide range of gate lengths (1-25 microns) and gate widths (2-130 microns), and transistor operation was obtained for both single and multiple graphene layers.