ELECTRICAL-PROPERTIES OF BORON-DOPED POLYCRYSTALLINE DIAMOND FILMS

Boron-doped (B-doped) polycrystalline diamond films (PDFs) were synthesized by thermal filament chemical vapour deposition, and the Hall effect, together with the resistivity of samples with different dosages, was measured by Van der Pauw's method. The Hall mobility and the hole concentration in the samples were also calculated. The experimental results show that B-doped PDFs are p-type semiconductors in which the resistivity has decreased by 11 orders of magnitude compared with the intrinsic samples (from 10(9) OMEGA cm to 10(-2) OMEGA cm). The activation energy of the B-doped PDFs was reduced through 0.307 eV (for lightly doped PDFs) to 0.075 eV (for heavily doped PDFs). However, the Hall mobility of the samples was only about 7 cm2 V-1 s-1 and was almost independent of the impurity concentration. A preliminary discussion of the experimental results is also given in this paper.