Fabrication and characterization of GaAs nanoparticles achieved using femtosecond laser ablation

Abstract

GaAs Nanoparticles (NPs) were produced using femtosecond pulsed laser (∼50 fs, 1 kHz repetition rate, 800 nm) ablation of bulk GaAs in distilled water. Effect of different laser energies such as 100 μJ, 200 μJ, and 500 μJ on the produced NPs was investigated. The produced NPs possessed size distribution in the range of 10–200 nm, most of the particles having an average particle size around 57 nm. In addition, nanoflake like structures having amorphous nature were also observed. With an increase in laser energy it was observed that there was a slight increase in the NPs size. For ablation performed at an energy of 500 μJ, a clear colour change (yellowish) of solution was observed due the increase in the efficiency of ablation, which could be due to a higher concentration of the NPs. Optical properties of these nanoparticles depict the absorption in the range of 264–274 nm and emission in the range of 410–440 nm. The longitudinal optical phonon-plasmon coupled (LOPC) and longitudinal optic (LO) modes observed near 266 cm−1 and 288 cm−1 in the Raman spectrum confirmed the presence of GaAs. The small shift observed in the Raman modes of GaAs NPs may be due the stress formed during the ablation. The X-ray diffraction studies revealed that the produced nanoparticles possessed cubic zinc blende structure of the GaAs.