Locally enhanced cathodoluminescence of electrochemically fabricated gold nanostructures

Three dimensional structures of Au with submicron sizes and high aspect ratios were fabricated by electrochemical micromachining with short voltage pulses. Due to the use of LiCl/dimethyl sulfoxide electrolytes, submicrometer machining-precision was achieved with voltage pulses of moderate duration of the order of 10 ns. Careful adjustment of the machining parameters like rest potentials of tool and workpiece and pulse amplitude allowed for the routine fabrication of Au microstructures. The optical properties of such structures were investigated by measuring their cathodoluminescence upon electron irradiation in a scanning electron microscope. Excitation of localized plasmons in small structures led to the enhancement of the light emission by a factor of up to 2.5, if compared to the bare Au surface.