Periodic submicrometer dot structures on n-GaAs substrates fabricated by laser-induced surface electromagnetic wave etching

Periodic submicrometer dot structures were fabricated by laser-induced surface electromagnetic wave (SEW) etching of n-GaAs substrates using the holographic exposure system of the frequency-tripled Nd:YAG laser. The shorter and longer diameters were about 310 and 540 nm, respectively. Spatial periods along two perpendicular axes were 370 and 545 nm, respectively. These periods were nearly in agreement with the calculation. The period of SEW grating depended on not only the laser wavelength, but also the number density of the laser-induced quasifree carriers.