Close to charge neutrality, graphene's energy landscape is highly inhomogeneous, forming a sea of electron-like and hole-like puddles that determine the properties of graphene at low carrier density. However, the details of puddle formation have remained elusive. By combining numerical calculations with low temperature scanning probe measurements we demonstrate that the autocorrelation function for the puddle landscape depends on the effective screening length and the typical distance $d$ of the long-range impurities from the graphene sheet. We use this theory to quantitatively explain the striking differences in the STM measurements of electron and hole puddles found in monolayer and bilayer graphene for nominally the same disorder potential.
Citation: Physical Review B
Pub Type: Journals
graphene, monolayer, bilayer, disorder, STM