Probing the subband structure of a wide electron system in a parabolic quantum well via capacitance-voltage measurements

Low-temperature capacitance-voltage measurements in an electron system realized in a remotely doped, wide AlGaAs parabolic quantum well show small (∼1%) capacitance steps whose positions coincide with the calculated and independently measured front gate voltages at which the electric subbands are depopulated. The step positions respond to an applied in-plane magnetic field or a back-gate bias, in a manner consistent with the magnetic or electric depopulation of the subbands, respectively. We conclude that these steps are indeed related to the subband structure of the electron system.