Ge nanocrystals (NCs) are produced by a dewetting process
during annealing of an amorphous Ge layer deposited on an ultra thin
SiO2 layer. We have investigated the characteristics of the resulting
NCs as a function of the nominal Ge layer thickness. Thanks to transmission
electron microscopy images, we have extracted both the wetting angle and the
NCs aspect ratio. We found that these characteristics remain constant
whatever is the nominal thickness in the range of 1.5 to 10 nm. These
results suggest that NCs have reached their equilibrium shape. We also
experimentally determined the evolution of the NCs with the nominal
thickness of the amorphous layer and found a linear relation. These results
are in agreement with mass conservation and energetical considerations.
Moreover a memory effect was evidenced in all the samples by C − V measurements.
At last, we demonstrate that the use of a patterned SiO2 surface
improves considerably the ordering of NCs and reduces their size
distribution. Such a process is promising for future integration of NCs in
memory devices.