Microwave transport and noise in graphene devices

We report on microwave transport and noise in graphene sheets, capacitors and transistors. We achieved a transit frequency of 80 GHz in graphene-on-sapphire transistors [1]. This is close to the state-of-the art for a 200nm gate length. In order to investigate electronic diffusion in graphene we have realized 10 GHz bandwidth experiments in metal-oxide-graphene capacitors. The crossover from capacitor to skin-effect limited cavity regimes provides an accurate and direct measurement of the diffusion constant D($\varepsilon )$. We find D to be energy independent, which points to a mass-disorder scenario [2]. Finally, we have measured the shot noise of CVD graphene in a broad range of bias up to 1V drain-source voltage. In our GHz-frequency measurements we observe a Fano factor exhibiting the three characteristic regimes of electron-impurity, electron-electron and electron-phonon interactions. \\[4pt] [1] E. Pallecchi et al, Appl. Phys. Lett. 99, 113502 (2011) \\[0pt] [2] E. Pallecchi et al, Phys. Rev. B 83, 125408 (2011)