DETERMINATION OF THE TYPE OF CHARGE-CARRIERS IN CARBON FIBER POLYMER COMPOSITE/

The Hall effect method has been used to determine the charge carrier-d ensity in polycarbonate/carbon fibers composites. it uas found that th e measured Hall voltage varies almost linearly with Hall current. This behavior indicates that the majority of the charge carriers is of one type. The sign of the slope of this relation varies from positive to negative for composite specimens of about 18 wt% carbon fibers. This s uggests that a composite of low fiber content is functioning as p-type material and then changes to n-type with increasing carbon fiber cont ent. The observed anisotropic behavior of the charge carrier density m akes it difficult to calculate the kinetic parameters of the carrier m obility of such composite materials from the Hall effect analysis. (C) 1998 Elsevier Science Ltd. All rights reserved.