Noise characteristics of sequential tunneling through double-barrier junctions

The shot noise and I-V characteristics of multilevel resonant-tunneling systems are investigated in a stochastic description including strong time correlation derived from the Pauli exclusion of tunneling electrons. In the first resonance regime, one tunneling electron occupying a quantum-well quasibound state blocks one channel for the follow-up electrons. This correlation suppresses the shot noise. In the second (and higher) resonance regime, the tunneling electrons in the quantum well, when experiencing strong inelastic scatterings, fall immediately to occupy the low-lying off-resonance subband states and thus do not block the tunneling channels of others. There the noise power density may approach the full shot-noise level and the tunneling current can be enhanced.