About the origin of the low wave number structures of the Raman spectra of heavily boron doped diamond films

We study the Raman spectra of heavily boron ([B] > 3 x 10(20) cm(-3)) polycrystalline and homoepitaxial diamond films. A detailed comparison of the structures of these spectra can be done only after normalizations. As [B] increases in polycrystalline and homoepitaxial films, (i) the '1225 cm(-1)' appear identical GO the maximum of the '500 cm(-1)' band shifts to lower wavenumbers while its intensity increases GO the overall shapes of the '500 cm(-1)' bands remain similar while their full widths at half maximum are higher in the polycrystalline films. From these characteristics and previous works, the '500 cm(-1)' band is proposed to originate from local vibrational modes of boron pairs. (C) 2003 Elsevier B.V. All rights reserved.