Structure, Raman scattering, and transport properties of boron-doped graphite

Boron-doped highly oriented graphite films (B-HOGF's) with an atomic fraction of boron from 0.4 up to 2.2 at. % have been prepared from well-crystallized, highly oriented graphite. The effect of boron doping on crystal structure has been investigated in terms of texture observation with a field-emission gun-type scanning electron microscope and by measurements of the x-ray diffraction and Raman scattering. The results indicate that in B-HOGF's, boron atoms substituted in the graphite lattice and induced disorder, which caused the Raman bands related to the disorder in graphite layer planes to appear. For each of the B-HOGF's, the temperature dependence of the resistivity in a range 1.8--300 K has been measured. The Hall coefficient and transverse magnetoresistance have also been measured at 3.0 K in a magnetic field range up to 4 T. The Hall coefficient data indicate that each of the B-HOGF's is a mixed crystal of graphite grains with and without boron atoms. The temperature dependence of the resistivity and field dependence of the transverse magnetoresistance for B-HOGF's show a characteristic that is possibly explained by a three-dimensional weak localization theory proposed by Sugihara Hishiyama, and Kaburagi.