Enhancement in conductivity of boron doped diamond films deposited by the methanol/acetone/B2O3 system

The gaseous boron sources such as trimethylboron and borane have been wildly used for boron-doping of diamond film with a high conductivity. Methanol and acetone/B2O3/CH4 (C-B with CH4) has also been selected as a doping system for its low cost. But the resulting boron-doped diamond (BDD) film exhibited a lower conductivity. The BDD film was deposited by the system of methanol and acetone/B2O3 without CH4 (C-B) and exhibited a higher conductivity and larger carrier concentration. It is found that oxygen plays an important role during the deposition. A large number of vacancies for boron filling can be generated in the diamond film from the CO bonds. The addition of CH4 decreased the number of oxygen atoms so that fewer vacancies occurred. Enhancement in conductivity results from more boron atoms in the diamond film using the mixed methanol/acetone/B2O3 system.