Spatially indirect transitions due to coupling between a hole accumulation layer and a quantum well in resonant-tunneling diodes

Spatially indirect transitions have been observed in a resonant-tunneling light-emitting diode that featured one shallow barrier. This causes wave-function extension across the shallow barrier leading to spatially indirect optical transitions between the electron subband in the well and the hole subband in the hole accumulation layer. In contrast to the previously observed redshift of indirect transitions in strongly coupled quantum wells, the indirect nature of these transitions causes a strong blueshift with bias. This is in agreement with the self-consistent modeling of the band structure.