Charged-impurity scattering in graphene

Abstract

These authors contributed equally to this work. Since the experimental realization of graphene 1 , extensive theoretical work has focused on short-range disorder 2-5 , "ripples" 6, 7 , or charged impurities 2, 3, 8-13 to explain the conductivity as a function of carrier density σ(n)[1,14-18], and its minimum value σ min near twice the conductance quantum 4e 2 /h[14, 15, 19, 20]. Here we vary the density of charged impurities n imp on clean graphene 21 by deposition of potassium in ultra high vacuum. At non-zero carrier density, charged impurity scattering produces the ubiquitously observed 1, 14-18 linear σ(n) with the theoretically-predicted magnitude. The predicted asymmetry 11 for attractive vs. repulsive scattering of Dirac fermions is observed. σ min occurs not at the carrier density which neutralizes n imp , but rather the carrier density at which the average impurity potential is zero 10 . σ min decreases initially with n imp , reaching a minimum near 4e 2 /h at non-zero n imp , indicating that σ min in present experimental samples does not probe Dirac-point physics 14, 15, 19, 20 but rather carrier density inhomogeneity due to the impurity potential 3, 9, 10 .

Broadband graphene terahertz modulators enabled by intraband transitions

“…An insertion loss of 5% is close to our experimental observation while being a conservative estimate of the graphene minimum AC conductivity 19,36 , based on the experimentally measured DC conductivity 37 . This means that extremely low intrinsic signal attenuation can be achieved in graphene terahertz modulators: < 0.2 dB per single-layer graphene.…”

Tuning the Electronic Structure of Graphene by an Organic Molecule

“…However, distribution of the metal atoms on the graphene surface is usually inhomogeneous, and the resulting charged impurities cause significant reduction of the carrier mobility. 14 The single, open-shell NO 2 molecule is found to be a strong acceptor, whereas its equilibrium gaseous state N 2 O 4 acts as a weak dopant and does not result in any significant doping effect. 15 Boron or nitrogen substitutional doping is also not reliable and always induces defects that destroy the promising electronic property of graphene.…”

“…TCNE molecules are more advantageous compared to alkali atoms because the intermolecular repulsive interaction leads to uniform distribution of the molecules at increasing coverage. 14 The P-N junction is a basic unit in integrated circuits, and it is desirerable to fabricate P-N junctions on a graphene layer for graphene-based electronic devices. An organic molecule may be useful for achieving this goal.…”

Stability of suspended monolayer graphene membranes in alkaline environment

“…The sheet resistance is high, and the Dirac neutrality point is not visible in the explored backgate voltage range. This is due to the presence of residuals and impurities on the surface of graphene, which act as scatterers and degrade the conductance [43,44]. In order to improve the electrical properties of graphene, we performed current annealing [45], that is the application of a controlled large current to recover its electrical properties.…”