Characterization of individual diamond crystals in micro diamond arrays using an AFM-based technique

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Micro diamond arrays (MDA), in which thousands of diamond micro particles are aligned in μm scale accuracy, were fabricated by site-selective plasma chemical vapor deposition (PCVD). This method is based on the higher nucleation density of diamond on Pt than on SiO 2. When a Pt substrate covered with a SiO 2 film with photolithographically prepared holes of 2 μm in diameter was treated under appropriate PCVD conditions, a single diamond crystal particle nucleated selectively at the bottom of each hole where the Pt surface was exposed. In this manner, a MDA was formed on the substrate. Individual diamond crystals of the MDAs were characterized using an AFM-based technique in which topographic and electrical conductivity information could be simultaneously acquired. A DC bias with respect to the grounded gold-coated AFM-probe was applied to the Pt layer underneath the diamond crystals. Inhomogeneous electrical conductivity in each of the diamond microcrystals was clearly observed with resolution better than 50 nm. The peak current in conductive regions reached up to the μA order, while that in nonconductive regions was less than 10 pA. Such inhomogeneity was not observed in the corresponding topographic images obtained.