We compare GaAs quantum dots (QDs) grown on GaInP and GaAs surfaces by droplet epitaxy at different temperatures. Whereas small GaAs QDs on GaInP surfaces, similar to GaAs surfaces, but with much poorer homogeneity, are only obtained at a low growth temperature of 200 degrees C, no QDs are observed at higher temperatures and even nanoholes are formed at 300 degrees C in the GaAs/GaInP system. In contrast, the GaAs/GaAs QDs are well observable at higher temperatures. We discuss the destabilization process of GaAs QDs on GaInP in the frame of phosphorus outdiffusion processes. We suggest that already the Ga droplet formation is affected prior the crystallization step. (C) 2009 Elsevier B.V. All rights reserved.