QUASI-ONE-DIMENSIONAL TRANSPORT OF NONDEGENERATE ELECTRONS IN 2-DIMENSIONAL SYSTEMS WITH A FLUCTUATION POTENTIAL

A threshold vanishing of the Hall emf with decreasing gate voltage is observed at approximate to 77 K in semiconductor systems which are dis ordered as a result of a high built-in charge density near the plane o f the 2D-electron channel. The effect is observed at a channel conduct ivity a approximate to e(2)/h and is due to a transition to nondegener ate-electron transport via a 2D percolation cluster having a quasi-1D character of the conduction. We have established that the conductance of ''short'' structures, having a length of the order of the correlati on length of a percolation cluster, equals approximate to e(2)/h per e lectron and is determined by isolated percolation paths having a lower ed percolation threshold. These phenomena are a general property of di sordered 2D systems. (C) 1997 American Institute of Physics.