Figure 4

AFM images of different stages of the nanodrilling process and profiles along the$\left[\mathbf{1}\overline{\mathbf{1}}\mathbf{0}\right]$direction. (a-e) 500 × 500 nm² AFM images of different stages of the nanodrilling process during the Ga droplet consumption. (f) Profiles along the $\left[1\overline{1}0\right]$ direction [dashed line marked in (e)], normalized to the smallest ring diameter, showing the progressive droplet reduction, the local etching of the GaAs substrate, and the progressive filling of the part of the hole free of Ga droplet.