  In the present work the possibility of simultaneous localization of two
electrons in $\Delta^{100}$ and $\Delta^{001}$ valleys in ordered structures
with Ge/Si(001) quantum dots (QD) was verified experimentally by the electron
spin resonance (ESR) method. The ESR spectra obtained for the ordered
ten-layered QD structure in the dark show the signal corresponding to electron
localization in Si at the Ge QD base edges in $\Delta^{100}$, $\Delta^{010}$
valleys ($g_{zz}$=1.9985, $g_{in-plane}$=1.999). Light illumination causes the
appearance of a new ESR line ($g_{zz}$=1.999) attributed to electrons in the
$\Delta^{001}$ valley localized at QD apexes. The observed effect is explained
by enhancement of electron confinement near the QD apex by Coloumb attraction
to the photogenerated hole trapped in a Ge QD.
