  A peculiarity of the single-electron transistor effect makes it possible to
observe this effect even in structures lacking a gate electrode altogether. The
proposed method can be useful for experimental study of charging effects in
structures with an extremely small central island confined between tunnel
barriers like a nanometer-sized quantum dot or a macromolecule probed with a
tunneling microscope), where it is impossible to provide a gate electrode for
control of the tunnel current.
