Irradiation and Annealing Effects on the c-Axis Electrical Resistivity of Graphite

Changes in the c -axis electrical resistivity of pyrolytic graphite due to electron irradiations at 80 K and due to subsequent isochronal pulse annealings up to 400 K wave measured. The average carrier mobility in the c -axis direction was calculated from the c -axis resistivity by the use of the carrier density obtained through the a -axis galvanomagnetic property measurements. The c -axis resistivity decreased by irradiation at 80 K. The reciprocal of the average carrier mobility in the c -axis direction increased by 7±2 mV ·sec·cm- 2 per ppm of Frenkel defects. As to thermal annealings, the c -axis electrical resistivity showed peculiar features compared with the a -axis one. The reciprocal of the average carrier mobility in the c -axis direction, however, showed nearly the same changes in relative values as that in the a -axis direction with annealing temperatures.