Extended Data Fig. 8: Independence of the hysteretic behaviour on the sweep rate.

a–c, Forward (red) and backward (blue) sweeps of the bottom-gate capacitance, C_b, from device H2 at fixed carrier density n_ext with sweep rates of 2.2 mV nm⁻¹ s⁻¹ (a), 4.5 mV nm⁻¹ s⁻¹ (b), and 9.8 mV nm⁻¹ s⁻¹ (c). Sweep rates shown in each panel denote the rate at which the externally applied displacement field D_ext/ε₀ was ramped in the BN dielectric layers. No noticeable variation was observed in the capacitance features for the large range of sweep rates.