Resonant Zener tunneling of electrons between valence-band and conduction-band quantum wells

We report the observation of resonant tunneling effects at high applied fields in the reverse-bias current-voltage characteristic of multiple quantum well p-i-n diodes. The Al_0.48In_0.52As/Ga_0.47In_0.53As structure (grown by molecular beam epitaxy with 35 periods of 139 Å barriers and 139 Å wells) shows two steps in the dark current. These are associated with Zener tunneling of electrons across the band gap from the lowest subband in the valence-band quantum wells to the first and second subbands of adjacent conduction-band wells.