  We implement a quantum approach which includes long range Coulomb interaction
and investigate current voltage characteristics and shot noise in double
barrier resonant diodes. Theory applies to the region of low applied voltages
up to the region of the current peak and considers the wide temperature range
from zero to room temperature. The shape of the current voltage characteristic
is well reproduced and we confirm that even in the presence of Coulomb
interaction shot noise can be suppressed with a Fano factor well below the
value of 0.5. This feature is a signature of coherent tunnelling since the
standard sequential tunnelling predicts in general a Fano factor equal to or
greater than the value 0.5. This giant suppression is a consequence of Pauli
principle as well as long range Coulomb interaction. The theory generalizes
previous findings and is compared with experiments.
