Fabrication of self-assembled Au droplets by the systematic variation of the deposition amount on various type-B GaAs surfaces

Abstract

The fabrication of self-assembled Au droplets is successfully demonstrated on various GaAs (n11)B, where n is 2, 4, 5, 7, 8, and 9, by the systematic variation of the Au deposition amount (DA) from 2 to 12 nm with subsequent annealing at 550°C. Under an identical growth condition, the self-assembled Au droplets of mini to supersizes are successfully synthesized via the Volmer-Weber growth mode. Depending on the DA, an apparent evolution is clearly observed in terms of the average height (AH), lateral diameter (LD), and average density (AD). For example, compared with the mini Au droplets with a DA of 2 nm, AH of 22.5 nm, and LD of 86.5 nm, the super Au droplets with 12-nm DA show significantly increased AH of 316% and LD of 320%, reaching an AH of 71.1 nm and LD of 276.8 nm on GaAs (211)B. In addition, accompanied with the dimensional expansion, the AD of Au droplets drastically swings on 2 orders of magnitudes from 3.2 × 1010 to 4.2 × 108 cm-2. The results are systematically analyzed with respect to the atomic force microscopy (AFM) and scanning electron microscopy (SEM) images, energy-dispersive X-ray spectrometry (EDS) spectra, cross-sectional line profiles, Fourier filter transform (FFT) power spectra, and root-mean-square (RMS) roughness as well as the droplet dimension and density summary, respectively.