  We report on the charge offset drift (time stability) in Si single electron
devices (SEDs) defined with aluminum (Al) gates. The size of the charge offset
drift (0.15 $e$) is intermediate between that of Al/AlO$_x$/Al tunnel junctions
(greater than 1 $e$) and Si SEDs defined with Si gates (0.01 $e$). This range
of values suggests that defects in the AlO$_x$ are the main cause of the charge
offset drift instability.
