Fig. 2

The AFM images and 2D-FFT spectra of Ga nanodroplets formed on the GaAs surfaces with ion beam parameters: a ion beam current = 0.27 nA and φ = 37°, b ion beam current = 0.93 nA and φ = 37°, c ion beam current = 3.71 nA and φ = 37°, d ion beam current = 0.27 nA and φ = 50°, e ion beam current = 0.93 nA and φ = 50°, and f ion beam current = 3.71 nA and φ = 50°. g–l The nanodroplet size distribution histograms of the AFM images in a–f, respectively