Hall Photovoltage Imaging of the Edge of a Quantum Hall Device

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Abstract
We report experiments using a Hall photovoltage imaging technique with a resolution of better than 5 μm to visualize the potential profile in a standard Hall bar device at low temperature and in high magnetic fields. The images show the potential rises sharply close to the device edges and is flat in the bulk. We obtain the characteristic length scale of the edge confining potential as 10 μm in our devices. This measurement enables the determination of the contribution of the edge current to the total Hall current. We also give a qualitative account of the origin of the photovoltage in the quantum Hall effect.