Barrier potential for laser written graphitic wires in diamond

Abstract

Diamond substrates supporting an internal array of conductive graphitic wires inscribed by a femtosecond pulse laser, are useful for the detection of ionising radiation in a range of applications. Various parameters involved in the laser fabrication process were investigated in this paper to understand their impact on the electrical properties of the wires. The study revealed an effect, whereby the wires exhibit insulating behaviour until a barrier potential is overcome. When high enough voltages are applied, the wires display ohmic behaviour. The magnitude of the barrier potential, which in some cases exceeds 300 V, is shown to be strongly dependent on the laser fabrication parameters. Through process optimisation, the potential barrier may be minimised and effectively removed, coinciding with reduced values of the wire resistance.

Ultrafast Laser Processing of Diamond Materials: A Review

“…Applying aberration correction resulted in a negligible barrier potential and a minimum value of the wire resistance. The obtained results were reproduced by multiple measurements [63]. Determining of the barrier potential could be a very important factor for the characterization of graphite wires fabricated by emerging methods, such as the use of Bessel beams [64] as well as for the design of wire junctions [65,66] or gaps in the conductive network [67].…”

“…The effect of laser processing parameters on the properties of graphite wires formed inside synthetic mono-and polycrystalline diamonds was investigated [63]. Wires were fabricated in CVD diamond samples using different light polarizations, processing speeds and laser pulse energies.…”

“…The output current was negligible until the applied voltage reached a threshold value. For values of the applied voltage exceeding the threshold voltage the wires exhibited ohmic behavior [63]. Graphite wires with larger diameter and lower resistance and barrier potential were formed with higher pulse energies.…”

A diamond gammavoltaic cell utilizing surface conductivity and its response to different photon interaction mechanisms

“…In this case, a stable and reproducible bulk counterpart to the surface termination would be graphite pillar electrodes. These are increasingly prevalent in diamond detectors [36,[57][58][59][60][61][62], but also have the distinction of having worked well in an energy device: the diamond photon-enhanced thermionic energy converter of Girolami et al [63].…”

Laser processing and electrical analysis of embedded graphitic wires in diamond

“…A Source Measurement unit (Keithley 2450 SourceMeter) measured the current-voltage relationship for the wires, in a voltage ramp of -50V to +50V at 5V resolution. Several tests demonstrated that only fabrication with optimized laser parameters generated wires showing measurable ohmic conductivity with the linear IV curve with no barrier potential[18].…”