Epitaxial growth on silicon carbide (SiC) is a method for producing large-area graphene. One of the promising properties of graphene is extremely high mobility of charge carriers. It has been reported that suspended graphene exhibits higher mobilities than graphene supported on a substrate because of absence of remote optical phonon scattering from the substrate . Recently, we demonstrated a technique for producing free-standing graphene on SiC using a photoelectrochemical (PEC) etch process and characterized the nanomechanical graphene resonators . In this work, we enable electron transport studies of suspended epitaxial graphene (SEG) on SiC. Our earlier work reported on SEG produced on n-doped SiC substrates . The PEC etch process requires a doped substrate for the etching reaction to proceed. The conducting substrate, however, rendered transport measurements in graphene difficult. In this work, semi-insulating SiC substrates were implanted using nitrogen in order to produce a thin doped top sacrificial layer for the PEC etch. Graphene was subsequently grown on the implanted substrates at a growth temperature of 1700<SUP>o</SUP>C in an argon atmosphere . The growth process also provided sufficient energy for activation of the implanted donors. Graphene thickness was estimated to be ~1.3 monolayers using X-ray photoelectron spectroscopy. Graphene was photolithographically patterned using an oxygen plasma and then the devices were exposed to the PEC etch. A critical point drying method was used to dry the suspended devices. Raman spectroscopy showed that the suspended devices are not chemically modified during the PEC process. Transport measurements showed no conduction between contact pads in the absence of graphene, indicating the complete removal of n-type implanted SiC. Further electrical measurements to characterize the devices are underway. References:
1. Bolotin, K. I.; Sikes, K. J.; Jiang, Z.; Klima, M.; Fudenberg, G.; Hone, J.; Kim, P.; Stormer, H. L. Solid State Commun. 2008, 146, 351. 2. Shivaraman, S.; Barton, R.A.; Yu, X.; Alden, J.; Herman, L.; Chandrashekhar, M.V.S.; Park, J.; McEuen, P.L.; Parpia, J.M.; Craighead, H.G.; Spencer, M.G. Nano Letters 2009, 9(9), 3105. 3. Emtsev, K.V.; Bostwick, A.; Horn, K.; Jobst, J.; Kellogg, G.L.; Ley, L.; McChesney, J.L.; Ohta, T.; Reshanov, S.A.; Röhrl, J.; Rotenberg, E.; Schmid, A.K.; Waldmann, D.; Weber, H.B.; Seyller, T. Nat Mater. 2009, 8(3), 203.