The surface m orphology of InAs quantum dots (QDs) on undoped Si (100) shows a strong dependency on surface pretreatments, with as much as 30% difference in island density with different size distributions. Lowering the V/III fluxes ratio (5 8: 1 to 10: 1) effectively suppresses the average height (47%) and increases density (75%) of QDs. While changing the growth temperature (220-300 degrees C) increased the average height by 62% on chemically etched Si surfaces, nucleation on the SiO2 surface was less sensitive to surface preparation. The authors alsd observe that the specific substrate orientation and annealing at 500 degrees C do not significantly impact the morphology of QDs. (c) 2007 American Vacuum Society.