REFLECTION OF BALLISTIC ELECTRONS FROM DIFFUSIVE REGIONS

We have investigated reflection of edge states from the boundary betwe en a disordered region and a high-mobility region of a two-dimensional electron gas. alpha-particle bombardment has been employed to reduce selectively the mobility. We observe an exponential increase in reflec tion of the innermost edge state from the disordered region as the tem perature decreases. The results are explained in terms of the Milne re flection of electrons which are elastically scattered back before ther malization can occur.