Quantum capacitance measurement in monolayer WTe2

Monolayer WTe2 has been demonstrated to be a two-dimensional topological insulator with a bulk gap and conducting edge states. However, the mechanism for the bulk gap formation has not been well understood. To address this question, we perform quantum capacitance measurement on monolayer WTe2 devices, using a highly sensitive capacitance bridge based on GaAs high electron mobility transistors (HEMT). The quantum capacitance is related to the density of states in the 2D sample. We will present the gate and magnetic field dependence of the quantum capacitance and discuss its relation with the bulk electronic structure as well as edge conduction in monolayer WTe2.