Improvement in electrical conductivity of boron-doped diamond films after hydrogen plasma and vacuum heat treatment

The electrical conductivity of Boron-doped diamond (BDD) films prepared by the mixture of methanol/acetone/B2O3 was significantly improved after hydrogen plasma and vacuum heat treatment. SEM and Raman spectro-scopy were used to characterize the change of morphology and quality of BDD film after heat treatment, and the electrical properties of BDD film were determined by Hall effect. The chemical bonding states of boron atoms were analyzed by X-ray photoelectron spectroscopy. A mechanism at the origin of the improved conductivity after the heat treatments was proposed. It is oxygen that provides new vacancies for the addition of more boron atoms at grain boundary into crystal lattice, thus enhancing the electrical properties. There are different roles of oxygen in different heat treatments.