resumo
The surface termination of as-grown microcrystalline (MCD) and nanocrystalline (NCD) boron-doped diamond films was assessed by X-ray photoelectron spectroscopy (XPS) and water contact angle techniques. The diamond coatings were grown on mirror-polished silicon nitride ceramic substrates using the hot-filament chemical vapor deposition (HFCVD) technique. The boron doping source, boron oxide (B2O3) diluted in ethanol, was dragged by a constant Ar flow at different CH4/H-2 gas ratios and system pressures. The electrical resistivity of these semiconducting diamond films was obtained and their surfaces were further characterized by scanning electron microscopy (SEM) and Raman spectroscopy. The results have shown that the increasing total pressure particularly affects the crystal size of the boron doped MCD samples by enhancing diamond renucleation due to the higher residence time of Ar. Also, both as-grown MCD and NCD surface types were found to be inherently hydrophobic, with contact angles similar to 90 degrees C, but retain significant amounts of oxygen bonded to carbon atoms mainly as C-O-C and C = O terminations. Such partial diamond surface oxidation is the result of a very unique stable gas mixture containing hydrogen, carbon and oxygen, when boron oxide and ethanol are added to methane during the CVD process. (C) 2016 Elsevier B.V. All rights reserved.
palavras-chave
CHEMICAL-VAPOR-DEPOSITION; HOT-FILAMENT CVD; ULTRAVIOLET RAMAN-SPECTROSCOPY; HIGH-TEMPERATURE VAPORIZATION; NANOCRYSTALLINE DIAMOND; THIN-FILMS; SILICON-NITRIDE; ELECTRODES; OXIDATION; BEHAVIOR
categoria
Materials Science
autores
Neto, MA; Pato, G; Bundaleski, N; Teodoro, OMND; Fernandes, AJS; Oliveira, FJ; Silva, RF
nossos autores
Filipe José Alves de Oliveira
Investigador Principal
Graça Pato
Bolseiro de investigação
Miguel Ângelo da Costa Neto
Investigador
Rui Ramos Ferreira e Silva
Professor associadoagradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.