The in situ deposition process of SiGe nanocrystals on SiO2 and HfO2 substrates was studied using Auger electron spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The Ge concentration in SiGe nanocrystals increased with deposition time at equal Si/Ge flow rates. Analysis indicated that the nucleation of Ge takes place preferentially on prenucleated Si on the dielectric. Memory transistors were fabricated using SiGe nanocrystals and HfO2 tunneling/control dielectrics as a gate stack. Memory effects from floating SiGe nanocrystals in HfO2 were clearly observed at room temperature from metal–oxide–semiconductor field effect transistor devices with a threshold voltage shift of about 0.5 V with the application of +4 V. © 2004 American Institute of Physics.