Enhancement of surface electrical current on silicon via nanodiamond particles deposited by pulsed spray technique

The deposition of as-received nanodiamond (ND) particles on silicon substrate was performed by the pulsed spray technique, using a dispersion of 250 nm ND in 1, 2-dichloroethane. A set of samples was sprayed by varying the number of pulses from 1 to 500. The morphology of the samples was characterized and monitored by means of optical, atomic force, and confocal microscopies. At a low number of pulses, sparse diamond particles were observed, whereas at a high number of pulses dense/quasi-continuous ND layers were formed. The electrical conductivity measurements of surface silicon substrate evidenced a remarkable change for the presence of ND particles. This behavior is also found by theoretical simulations (finite element method). Finally, a comparison between the electrical resistances measured on these samples versus the pulse number and the inverse current density calculated as a function of the number of ND particles, showed a good agreement. The experimental results highlighted an increase of the electrical current by using a number of pulses <100, whereas the simulation results proved the enhancement of current density and its surface rectification by employing a specific number of particles. The current increased by increasing the temperature and during the heating–cooling cycles hysteresis was observed. (a) Scheme of the sprayed ND particles on silicon substrate, (b) 3D AFM image 55 mm2 of 10 pulses sample, (c) trends of measured R and calculated 1/J.