  We demonstrate nanohole formation in AlGaSb by Ga droplet etching within a
temperature range from 270{\deg}C to 500{\deg}C, allowing a wide range of
tunability of the nanohole density. By leveraging the low vapor pressure of Sb,
we can obtain high degree of control over droplet formation and nanohole
etching steps and reveal the physics of adatom diffusion in these processes.
Furthermore, by combining the experimental results and a geometric
diffusion-based model, we can determine the temperature and
Sb-flux-dependencies of the critical monolayer coverage of Sb atoms required
for driving the droplet etching process to completion. These findings provide
new insight into the droplet formation and etching process present in the
droplet-mediated synthesis of semiconductor nanostructures and represent a
significant step towards development of telecom-emitting quantum dots in the
GaSb system.
