Imaging the Quantum Capacitance of Strained MoS2 Monolayers by Electrostatic Force Microscopy

= 300 MHz, we visualize simultaneously the bubble topography and its quantum capacitance. Our finite-frequency capacitance imaging technique is noninvasive and nanoscale and can contribute to the investigation of time- and spatial-dependent phenomena, such as the electron compressibility in quantum materials, which are difficult to measure by other methods.