Tunneling between edge channels and the bulk of a two-dimensional electron gas

We developed a method to study the potential distribution in a two-dimensional electron gas in a magnetic field with a nonequilibrium between edge channels and the bulk. The effective resistance determined as a function of dc bias shows that the coupling between the edge channels and the bulk is due to tunneling across the incompressible strips with integer filling factors. An additional dc bias changes both the width of the strip and the path for tunneling, resulting in a diodelike characteristic. Negative differential resistance was observed when two incompressible strips are developed at the edge.