  We study the transport and spectral property of a segmented diode formed by
an XX $+$ XXZ spin chain. This system has been shown to become an ideal
rectifier for spin current for large enough anisotropy. Here we show numerical
evidence that the system in reverse bias has three different transport regimes
depending on the value of the anisotropy: ballistic, diffusive and insulating.
In forward bias we encounter two regimes, ballistic and diffusive. The system
in forward and reverse bias shows significantly different spectral properties,
with distribution of rapidities converging towards different functions. In the
presence of dephasing the system becomes diffusive, rectification is
significantly reduced, the relaxation gap increases and the spectral properties
in forward and reverse bias tend to converge. For large dephasing the
relaxation gap decreases again as a result of Quantum Zeno physics.
