It is shown that in RTD GaN/AlGaN(0001) the internal fields manifest themselves in the asymmetry of the tunneling current via the value of the electronic charge in the quantum well. This charge is larger when the internal and external fields in the well compensate each other, resulting in smaller shifts of potential and resonance levels in the active region with voltage, in the higher resistance of the structure, and in the linear current– voltage dependence within a wide range of voltages. When the internal and external fields are the same, the current exhibits a sharp negative-differential-conductivity structure.

It is shown that wide hysteresis loop could arise in w-GaN/AlGaN(0001) double-barrier structures. The hysteresis loop depends on the mutual orientation of external and internal fields in the well and is wider at the voltage polarity when these fields compensate each other. It is established that the hysteresis loop can be relatively wide (~4 V) even in geometrically symmetric structures with the participation of two resonances.