Abstract
In this paper we report on both experimental and theoretical studies of the voltage drop across the source contact in the quantum Hall effect regime at high currents. Our investigations have been performed on the plateau v = 2 using two Hall bars of different widths, processed on the same sample. A steep increase of the voltage drop across the source contact is observed experimentally well before the breakdown of the quantum Hall effect. This behaviour is analysed in the framework of inter and intra Landau level scatterings. The theoretical curves reproduce correctly the main aspects of the experimental data. Our work corroborates the results published recently by the group of Komiyama upon the Landau emission of two-dimensional electron gas.