DEFECT CLUSTERING AND BORON ELECTRICAL DEACTIVATION IN P-DOPED POLYCRYSTALLINE DIAMOND FILMS

Heavily doped polycrystalline thin diamond films were prepared by chemical vapor deposition. Boron was introduced in the films during the deposition. The electrical activity of acceptors was studied using dc polarization technique and bulk admittance spectroscopy. In the concentration range of 10(17)-10(20) cm-3 we have observed the occurrence of Hubbard interaction and band splitting. The conductivity of the films is mobility limited, and the pre-exponential factor of sigma-(T) decreases as the total concentration of boron increases. The occurrence of boron-defect clustering has been detected, and its effect on the majority-carrier injection level is discussed.