Electrochemical characterization on semiconductors p-type CVD diamond electrodes

Semiconductor boron-doped CVD diamond films were prepared on Si substrates by the hot filament technique. The surface morphology analysis by SEM prese nted continuous and well faceted films. The samples were grown with differe nt boron concentrations by controlling the BIC ratio in the feeding gas. Ra man results showed a drastic change of diamond films for different doping l evels. The characteristic line at 1332 cm(-1) decreases and shifts to lower energy as a function of the film resistivity. It was also observed a broad peak around 1220 cm(-1) caused by the incorporation of boron in the diamon d lattice. Photocurrent-voltage behaviour of undoped and boron-doped diamon d electrodes was investigated in dark and UV visible irradiation. The volta mmograms showed that doped electrodes illuminated with a xenon lamp exhibit ed currents significatively higher because of the increased conductivity. F or undoped electrodes it was observed a small photocurrent for anodic and c athodic polarization in the order of mu A for the potential range of +1.0 V and -1.0 V (Ag/ASCl), for 1.0 M KCI. Mott-Schottky plots studied the inter facial processes at diamond-electrolyte junction. The flatband potential U- fb was found between 0.6 and 0.8 V (Ag/AgCl) which varies with the presence of sp(2)-type carbon as an impurity. From the curve slope the acceptor con centrations were found in the range of 10(18) and 10(21) cm(-3). These valu es agree with the estimated concentration obtained by Raman measurements.