Electrochemical characterization on semiconductors p-type CVD diamond electrodes

Abstract

Semiconductor boron-doped CVD diamond lms were prepared on Si substrates by the hot lament technique. The surface morphology analysis by SEM presented continuous and well faceted lms.The samples were grown with di erent boron concentrations by controlling the B=C ratio in the feeding gas. Raman results showed a drastic change of diamond lms for di erent doping levels. The characteristic line at 1332 cm ,1 decreases and shifts to lower energy as a function of the lm resistivity. I t w as also observed a broad peak around 1220 cm ,1 caused by the incorporation of boron in the diamond lattice. Photocurrent-voltage behaviour of undoped and boron-doped diamond electrodes was investigated in dark and UV visible irradiation. The voltammograms showed that doped electrodes illuminated with a xenon lamp exhibited currents signi catively higher because of the increased conductivity. F or undoped electrodes it was observed a small photocurrent for anodic and cathodic polarization in the order of A for the potential range of +1.0 V and -1.0 V Ag=AgCl , for 1.0 M KCl. Mott-Schottky plots studied the interfacial processes at diamondelectrolyte junction. The atband potential Ufb was found between 0.6 and 0.8 V Ag=AgCl which v aries with the presence of sp 2 -type carbon as an impurity. F rom the curve slope the acceptor concentrations were found in the range of 10 18 and 10 21 cm ,3 . These values agree with the estimated concentration obtained by Raman measurements. I IntroductionThe evolution of research on semiconductor diamond has shown promising results with doping process during CVD growth. Due to its easy production and high stability, there is a great interest in studying the development of boron doped diamond leading to the application of these lms as electrode for, photoelectrochemical PEC cells, sensors, etc 1-3 .The standard methods used for CVD boron-doped diamond were initially thermal di usion 4,5 and ion implantation 6,7 . These processes were made ex situ", after the lm growth. The main advantage is the no-contamination of the growth reactor. Martin et al. 4 have obtained highly doped lms, using in situ" process from a solid source of boron inside of the reactor. Better results that evidenced more homogeneous lms were observed. CVD-grown polycrystalline diamond lms, depending on growth conditions, can have a wide spectrum of electrophysical properties. Their properties depend on the concentrations of defects in diamond grains, on the volume fraction of the nondiamond intergrain boundary phase, and on its nature. Okano et al 8 have proposed the boron doping during the CVD growth process using the hot lament reactor introducing B 2 O 3 dissolved in methanol-acetona mixture, that works as a carbon source for diamond growth. Their results showed lms with linear relation between the doping levels and boron concentration.Pleskov et al. 9 have studied, for the rst time, the electrochemical and PEC behaviour of diamond electrodes. Tenne and Swain 10,11 have made cyclic voltammograms in the presence of redox couples. Sa...

Boron-doped diamond electrodes for carbofuran electrochemical degradation

“…Th e measurements were performed at amplitude of 10 mV and frequencies of 10 kHz. Th is procedure has been described in detail in previous work by the group INPE Diamond (23,24) . Th e Ti/BDD electrode presented donor density (N A ) values of 6.8 × 10 19 cm -3 boron atoms and the fl at band potential values (E FB ) was approximately at 1 V/MSE.…”

Estudo da fotoeletrodeposição de partículas de cobre sobre filmes de diamante dopado com boro

“…Nesta relação, admite-se que toda a carga presente na camada de depleção é proveniente dos doadores ionizados. Portanto, um gráfico de C -2 em função de E informa sobre o nível de dopagem no semicondutor, permitindo estimar a densidade efetiva dos portadores de carga (NA) e também o potencial de bandas planas (EFB) (16) .…”

Influência do eletrólito na eletrodeposição de nanopartículas de Cu sobre eletrodo de diamante dopado com boro

“…Um pico definido em torno de 1320 cm -1 é característico do diamante (1332 cm -1 ) e está deslocado para menores energias devido às tensões causadas pela incorporação de boro na rede cristalina. 36 As duas bandas localizadas em 500 e 1230 cm -1 estão associadas à incorporação de…”