2D TRANSPORT AT THE SURFACE OF A 3D QUANTUM HALL SYSTEM

We have made electronic transport studies of the integer quantum Hall effect in a three-dimensional, layered semiconductor structure. When i n-plane transport is quantized, the dependence of the vertical conduct ance G(zz) on device size shows that current Bows via extended surface states, which form from the coupled edge states in each layer. As the temperature rises, bulk transport begins to dominate G(zz), giving ro ughly activated behavior at high T. Data on in-plane transport demonst rate a very small energy scale for the rise in longitudinal resistance , R-L,. (C) 1998 Elsevier Science B.V. All rights reserved.