  Defects of Ge quantum dot arrays may affect the electrophysical,
photoelectrical or optical properties of Ge/Si heterostructures as well as the
functionality of devices produced on their basis. The defects of Ge quantum dot
arrays formed at moderate temperatures on the Si(001) surface have been
investigated by the ultra high vacuum scanning tunnelling microscope integrated
with the molecular beam epitaxy chamber. A preliminary classification of the
defects has been carried out. Morphological peculiarities of the defects have
been studied. The surface densities of defects of different types have been
determined.
