Scanning capacitance imaging of compressible quantum Hall effect stripes formed at the sample edge and at a potential fluctuation

We investigate the local conductivity of a two-dimensional electron gas (2DEG) in the regime of the quantum Hall effect with a scanning capacitance microscope. At integer Landau level filling factors the bulk of the sample is insulating, whilst we find a well-defined narrow stripe of high local conductivity at the physical edge of the standard Hall device. Away from integer filling the conductivity of the Hall bar is homogeneous, similar to the zero field case. In addition, we discuss an anomalously broadened stripe around a locally depleted region of the 2DEG. We attribute the increased width of this stripe to a shallower potential gradient compared to the sample edge.