1. Morphology and Mobility of Graphene on SiC(0001) Randall M. Feenstra, Carnegie-Mellon University, DMR 0503748 Graphene formed on the (0001) surface of SiC (the so-called carbon-face) has different properties than that formed on the (0001) surface (the silicon-face). We have formed high quality graphene on the carbon-face by heating SiC in ultra-high-vacuum, and together with collaborators at MIT Lincoln Labs we have fabricated field-effect transistors. Mobilities of >4000 cm 2 /Vs are found, which is state-of-the- art for such devices. Much better uniformity in the mobilities over the surface is found compared to similar results on the silicon-face, owing to the improved uniformity of the graphene on the carbon-face. (a) AFM image of 9 ML graphene film, displayed with 4 nm gray scale range. (b) Optical micrograph of patterned graphene channel (10  m long), with source and drain. (c) Histogram of mobilities for various devices. (a) (b) (c)

2. Lack of Accumulation in Tunneling Spectra of GaAs(110) Randall M. Feenstra, Carnegie-Mellon University, DMR 0503748 A major unsolved problem in the area of tunneling spectroscopy of the (110) surface of III-V semiconductors has been the lack of accumulation current in situations where it is expected to occur. In the figure, the experimental data shows the current components from the conduction band (C) and valence band (V), as well as midgap current due to the n-type doping (D). Minimal or no accumulation in the semiconductor is found. We have successfully modeled the data by considering the role of a surface state band (resonant with the conduction band) in limiting the formation of an accumulation layer the semiconductor. C D V (a) Tunneling spectra. (b) and (c) Band bending diagrams, with (b) depicting no surface states and the resulting accumulation states (blue), and (c) showing a band of surface states (green). ECEC EFEF ECEC EFEF (a) (b)(c)

3. A happy Graduate Student following his Ph.D. Defense! Randall M. Feenstra, Carnegie-Mellon University, DMR 0503748 Graduate student support constitutes the bulk of the NSF funding in the PI's group. The nominal funding for 1 student is leveraged with occasional departmental fellowships or teaching assistantships, to cover typically 1.5 students. This photo shows three grad students who have (or will) receive the majority of their funding from this NSF grant. Sandeep's work on pentacene was featured in our 2008 highlight, Luxmi's work on graphene has been shown in the 2008 and 2009 highlights, and Nishtha is a new grad student who is also working on graphene. Left to right: postdoc Patrick Fisher; grad students Sandeep Gaan, Luxmi, and Nishtha Srivastava, at a celebration following Sandeep's Ph.D. defense.