Nanoscale laser patterning of thin gold films

Square grids of gold dots were prepared from several nanometer gold films by locally confined excimer laser ablation. Diffraction-mask projection laser ablation at a wavelength of 248 nm was used to convert Au films of 3, 6 and 9 nm thickness on sapphire substrates into well-ordered arrangements of substrate-adhered gold nanodots. Employing a checkerboard phase mask, gold-cap diameters between 75 and 115 nm can be obtained. The methodology allows simultaneous ablation of areas of ∼50 × 50 µm in about 1 s and, hence, represents a valuable supplement to the more laborious methods currently in use for the preparation of nanodot template patterns for, say, nanowire growth.