Structural, spectroscopic, and electrochemical characterization of boron-doped diamond films from different provenances

Morphological, spectroscopic, and electrochemical aspects of boron-doped diamond (BDD) films grown on silicon surfaces originating from three different laboratories have been examined by atomic force microscopy (AFM), Raman scattering, Auger electron spectroscopy, and cyclic voltammetry in polyethylene oxide LiClO₄ electrolytes in ultrahigh vacuum. All specimens displayed AFM images characteristic of diamond and Raman spectra consistent with a wide range of boron concentrations (10¹⁹ to 10²¹ B atom/cm³), with no evidence for the presence of gross graphitic impurities. The cyclic voltammetry of two of the specimens (denoted as GV2 and CWRU), however, showed features at potentials positive to lithium bulk deposition attributed to lithium-ion intercalation/deintercalation phenomena in nondiamond carbon present as a surface impurity, perhaps at the grain boundaries. This finding is consistent with earlier results for a specimen of type GV2 in aqueous electrolytes [Vinokur et al., J. Electrochem. Soc., 143, L238 (1996)], for which rates of heterogeneous electron transfer for certain redox couples were found higher than those for nominally clean BDD surfaces. .