Local electrical current and voltage of self-assembled nanodiamond pillars

The self-assembly of pillar-like structures in nanodiamond (ND) layers was obtained by means of a controlled pulsed spray technique. This technique enabled to deposit ND layers directly on silicon substrate using as-received 250 nm nanocrystals. The morphology of the obtained ND layer was characterized by confocal and atomic force microscopies, which provided evidence of the existence of self-assembled pillar-like structures due to the coffee stain effect. The local electrical current and voltage of an isolated ND pillar was also studied by scanning Kelvin probe microscopy (SKPM) and scanning capacitance microscopy (SCM). This study showed that the pillar features an increase of voltage (SKPM) and a decrease of current (SCM). Specifically, the pillar current is lower than that of the surrounding hole. A model based on the finite element method (FEM) confirmed the electrical behavior found by SCM.