Resonant effect of Zener tunneling current

We report the observation of a resonant effect of the Zener current through a $p-i-n$ diode structure. The second derivative of the $I-V$ characteristics, measured with a lock-in technique, shows several pronounced peaks. These peaks indicate that quasilocalized states in a quantum well in the intrinsic region are in resonance with Zener current. A calculation of the tunneling current based on tight-binding theory shows good agreement with our experimental results. The same holds for the calculated energetic positions of the localized electronic states. Altogether, these results indicate that the Zener current gets modulated due to Wannier-Stark resonances.