Current–voltage characteristics measured in triple barrier resonant tunneling diodes reveal new features about energy level alignment in a superlattice. Our data indicate that energy levels in the two quantum wells are not aligned at current peaks. Current peaks are observed when one of the energy levels in the two wells becomes resonant with the emitter level. One of the current peak was thermally activated, and showed inverted bistability at 77 K temperature. We explain that this is due toXstate assisted tunneling. ©1997 American Institute of Physics.