Fabrication of conductive micro electrodes in diamond bulk using pulsed Bessel beams

High-quality, in-bulk conductive graphitic microelectrodes are fabricated perpendicular to the surface of a 500 μm thick monocrystalline CVD diamond sample using pulsed Bessel beams. With a 12o cone angle beam, different pulse parameters are explored to optimize the graphitic wires which are written without sample translation. The quality of the electrodes and their electrical and structural properties have been analysed through current-voltage characterization and micro-Raman spectroscopy. We have found that higher pulse duration favours better conductivity while pulse energy has an optimum value for the same. This trend is confirmed by the presence and the different amounts of graphitic-like sp2 bonded carbon revealed by the micro-Raman spectra in different configurations. Using suitable writing parameters, we are able to create electrodes with the resistivity of 0.04 Ω cm, which, to the best of our knowledge, is one of the lowest values ever reported in literature in the case of graphitic-like wires fabricated through laser micromachining.