Boron Doped Ultrananocrystalline Diamond Films on Porous Silicon: Morphological, Structural and Electrochemical Characterizations

Boron doped ultrananocrystalline diamond (BDUND) films were grown and characterized on porous silicon (PS) substrates. PS samples were prepared from n-type monocrystalline silicon wafers (100) with 1-20 Ω.cm of resistivity, by electrochemical etching, using HF-acetonitrile solution as electrolyte. BDUND films were grown by Hot Filament Chemical Vapor Deposition using CH₄, H₂ and Ar. The doping process consisted of an additional hydrogen line, passing through a bubbler containing B₂O₃ dissolved in methanol, with boron/carbon ratio of 20000 ppm in solution. Raman spectroscopy and X-Ray diffraction were used to evaluate the quality of the films. Scanning electron microscopy was used for morphological characterization, and confirmed that the films covered the pores without filling them. Electrochemical response and capacitance behavior of the electrodes were explored, by cyclic voltammetry. Samples presented high capacitance, confirming that BDUND/PS electrodes are promising for application as electrochemical capacitors.

Keywords:
boron doped ultrananocrystalline diamond films; porous silicon; electrochemical application; capacitance