Charged Impurity Scattering in Graphene

Understand

Since the experimental realization of graphene1, extensive theoretical work has focused on short-range disorder2-5, ''ripples''6, 7, or charged impurities2, 3, 8-13 to explain the conductivity as a function of carrier density sigma_(n)[1,14-18], and its minimum value sigma_min near twice the conductance quantum 4e2/h[14, 15, 19, 20].

• Here we vary the density of charged impurities nimp on clean graphene21 by deposition of potassium in ultra high vacuum.
• At non-zero carrier density, charged impurity scattering produces the ubiquitously observed1, 14-18 linear sigma_(n) with the theoretically-predicted magnitude.
• The predicted asymmetry11 for attractive vs.