MAGNETIC OSCILLATIONS IN SEMICONDUCTOR POLYCRYSTALS AND POWDERS WITH 2D-CONDUCTIVITY CHANNELS

It is shown that magnetic oscillations, i.e. de Haas-van Alphen and Sh ubnikov-de Haas effects can be observed in semiconductor polycrystals or powders with two-dimensional conductivity channels on grain boundar ies or on the surface of crystal particles (in the case of powder). Th e requirements for the experimental observation of magnetic oscillatio ns are discussed. For typical values of the surface concentration of c arriers of 10(11)-10(12) cm(-2), oscillations exist in the high magnet ic field of 1-10 T. To detect the oscillations of kinetic characterist ics (SdH effect) the sample must satisfy two additional requirements, namely, 2D-channels must constitute a conduction cluster penetrating t hrough the whole sample, and the sample thickness must not exceed an a verage grain size. (C) 1998 Elsevier Science B.V. All rights reserved.