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. [GRAPHICS] (a) Scheme of the sprayed ND particles on silicon substrate, (b) 3D AFM image 5 x 5 mu m(2) of 10 pulses sample, (c) trends of measured R and calculated 1/J. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim