Accession Number : ADA191728

Title :   Photoconductivity in Carbon Fibers.

Descriptive Note : Rept. for 1 Sep 86-31 Aug 87,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Steinbeck, J ; Yu, F ; Braunstein, G ; Desselhaus, G ; Dresselhaus, M S

PDF Url : ADA191728

Report Date : 30 Oct 1987

Pagination or Media Count : 13

Abstract : Photoconductivity has been observed in vapor grown graphite fibers with a high quantum efficiency of carriers generated by photons. The photocurrent varies approximately as the square root of the intensity of illumination. No change in the growth or decay time of the photocurrent is observed as a function of illumination intensity or of the temperature. The photocurrent observed in semi-metallic graphite fibers is attributed to transitions between localized defect states which act as traps for photo-exited carriers. As the heat treatment temperature is raised above 1500 Kelvin, vapor grown graphite fibers show a decrease in the photocurrent due to the annealing of defects and an increase in the electron-hole recombination time. Keywords: Photoconductivity, graphite fibers, Effect of heat treatment temperature.

Descriptors :   *CARBON FIBERS, *HEAT TREATMENT, *PHOTOCONDUCTIVITY, ANNEALING, DECAY, DEFECTS(MATERIALS), ELECTRONS, GRAPHITE, HIGH RATE, HOLES(ELECTRON DEFICIENCIES), ILLUMINATION, INTENSITY, METALLOIDS, PHOTONS, QUANTUM EFFICIENCY, RECOMBINATION REACTIONS, SQUARE ROOTS, TEMPERATURE, TIME, VAPORS, THERMAL PROPERTIES

Subject Categories : Refractory Fibers
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE