Аннотация:Overlap-type single-electron transistors with the different island to substrate contact areas were studied. We found that background charge noise reduces with the contact area reduction, that clearly indicates to the substrate origin of the noise. For transistors with the smallest contact area with the substrate (stacked configuration), we reached the noise level of 2.5.10-5 e/√Hz at 10 Hz, which is the lowest noise figure of SET devices measured so far