Investigation on boron-doped CVD samples

The present work reports the investigations of the optical properties of B-doped CVD diamond films as a function of temperature, in the energy range from 500 to 5000 cm(-1) for temperatures between 14 and 620 K. The peaks corresponding to hole internal transitions and to one-phonon transitions were observed. Their intensities decreased as the temperature increased; a detailed study of the system showed that, as expected, at high temperature this is due to boron ionisation. At lower temperatures, however, thermalisation between the different electronic states of boron occurs. An increase in the background absorption with increasing temperature was also observed as a result of internal transitions of the holes within the valence band. (C) 2002 Elsevier Science B.V. All rights reserved.