Laser-Driven Growth of Silver Nanoplates on p-Type GaAs Substrates and Their Surface-Enhanced Raman Scattering Activity

Contact between aqueous solutions of silver nitrate (AgNO 3 ) and pristine surfaces of p-type gallium arsenide (GaAs) wafers results in essentially no reaction at room temperature and in the dark. The galvanic reactions between the GaAs wafers and AgNO 3 can be triggered under illumination of laser beams with power densities higher than a critical value (∼15 mW/cm 2 for a 630 nm laser), resulting in the growth of silver (Ag) nanoplates on the GaAs surface. The density and dimensions (including both thickness and edge length) of the resulting nanoplates can be readily tuned by controlling the growth time and laser power density. The as-grown Ag nanoplates on the substrates significantly enhance Raman signals of interesting molecules and serve as a new class of promising surface-enhanced Raman scattering substrates for sensitive chemical detection.