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Transport in chemically doped graphene in the presence of adsorbed molecules E. H. Hwang, S. Adam, and S. Das Sarma
 

Summary: Transport in chemically doped graphene in the presence of adsorbed molecules
E. H. Hwang, S. Adam, and S. Das Sarma
Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
Received 30 October 2006; revised manuscript received 9 October 2007; published 15 November 2007
Motivated by a recent experiment reporting on the possible application of graphene as sensors, we calculate
transport properties of two-dimensional graphene monolayers in the presence of adsorbed molecules. We find
that the adsorbed molecules, acting as compensators that partially neutralize the random charged impurity
centers in the substrate, enhance the graphene mobility without much change in the carrier density. We predict
that subsequent field-effect measurements should preserve this higher mobility for both electrons and holes, but
with a voltage induced electron-hole asymmetry that depends on whether the adsorbed molecule was an
electron or hole donor in the compensation process. We also calculate the low density magnetoresistance and
find good quantitative agreement with experimental results.
DOI: 10.1103/PhysRevB.76.195421 PACS number s : 81.05.Uw, 72.10. d, 73.40. c
I. INTRODUCTION
The recent discovery of graphene--a single layer of
graphite--followed by the rapid progress in fabricating tran-
sistorlike devices and measuring its transport properties1,2
is
an important, perhaps seminal, development in low-
dimensional electronic phenomena in nanostructures. These

  

Source: Adam, Shaffique - Condensed Matter Theory Center, University of Maryland at College Park

 

Collections: Physics