LAUSR

Quantum capacitance (Cq), which arises from the lack of charge carriers in low dimensional metallic materials, can be used to explore intrinsic properties of materials such as their density of states or residual carrier density when properly extracted. Here, Cq is extracted from the measured total capacitance of graphene-based devices using a dual-gated FET configuration with an oxidized aluminum/aluminum top-gate at room temperature. Acquired Cq is well in agreement with a theory for ideal graphene except for near Dirac point. The discrepancy in values near Dirac point is then adjusted by considering extra residual carrier density induced from charged impurities at finite temperature. The modified theory with residual carriers shows a great agreement with Cq measurements with the extracted residual carrier density of n* = 3.58 × 1011 cm−2.