We have studied the growth of GaSb quantum dots (QDs) by droplet epitaxy and found two different growth modes. In one mode, GaSb QDs are directly formed from Ga droplets by supplying Sb molecules (P-Sb similar to 1.1 x 10(-6)Torr) at a relatively high temperature (T-s=300 degrees C). In the second mode, dots are formed in two steps; Ga droplets are exposed to Sb flux (P-sb similar to 1.3 x 10(-6)Torr) at a low temperature (T-s=200 degrees C) to be clad by large granular crystals of Sb and then GaSb QDs are formed by desorbing the Sb polycrystalline grain layer at T-s=310 degrees C. GaSb QDs grown in the second mode are larger than original Ga droplets, whereas QDs grown in the first mode are smaller. The proper setting of the Sb flux and the substrate temperature to select either one of the modes is presented. (C) 2009 Elsevier B.V. All rights reserved.