We investigated the I-V characteristics of the double barrier stair-we
ll structure. Resonant tunneling current is achieved by application of
an electric field, which increases the transmission under positive bi
as and decreases it under the reverse bias. This asymmetry can be used
for rectification and the device works as a quantum diode. Furthermor
e, the same structure can perform, under negative bias, resonant tunne
ling processes with different characteristics.