ABSTRACT
We investigated transport properties of triple barrier resonant tunneling diodes. Due to the additional well and barrier inserted, the capacitance in this structure is reduced compared to that of a double barrier resonant tunneling diode. Current-voltage characteristics measured in three different structures show that resonance voltage shifts when the well width is changed. The origin of each resonance can be identified by relating the voltage shift to the width change. Contrary to the generally accepted picture, our data indicate that the energy levels in the neighboring wells are not aligned at resonance. Whenever any quantum well energy level becomes resonant with the emitter level, current shows a resonance.
