INSIDE A 2D ELECTRON-SYSTEM - IMAGES OF POTENTIAL AND DISSIPATION

Lateral potential distributions in 2D electron systems are imaged under magnetotransport conditions with an electrooptic method. In low mobility delta-doped samples, the results agree with a classical picture in the ohmic regime. For high currents, a uniform breakdown is found. In high-mobility modulation-doped heterostructures, the change in the potential distribution at breakdown is strongly asymmetric upon current reversal.