Abstract
We have studied the dependence of noise characteristics on the dimension of electron confinement of quantum devices at low temperature. By using the nonequilibrium Green's function method, we have found that in a double barrier resonant tunneling diode the shot noise is suppressed only around the bias voltage of the resonant tunneling and the noise suppression is more than half of the full shot noise in case of symmetric structures with thin barriers. On the other hand, in the Coulomb staircase characteristics of a quantum dot with equal barriers, the shot noise is suppressed on an average about half of the full shot noise while further drops are observed at the current-step voltages.