Sub-10-nm multifacet domelike Ge quantum dots grown on clean Si (001) (2x1) surface

Sub-10-nm multifacet domelike Ge quantum dots (QDs) ensembles with uniform size have been achieved on a clean Si (001) (2x1) reconstructed surface at a substrate temperature of 450A degrees C, total Ge coverage of 7 ML, Ge deposition rate of similar to 0.0115 ML/s and no post-annealing. Their areal density and diameter are 5.2x10(11) cm(-2) and 7.2 +/- 2.3 nm, respectively, which is explained by a pit-mediated mass transferring nucleation mechanism suggested by us. According to the phase diagram analysis, their domelike morphology can be attributed to a relatively high growth temperature. Their high density and small size result in a strong non-phonon peak with a large blue shift of 0.19 eV in the low-temperature photoluminescence spectrum.