Luminescence studies of resonant tunneling in a triple barrier structure with strongly coupled quantum wells

The electrical and optical properties of an n-oped triple barrier resonant tunneling diode are investigated. A thin central AlAs barrier provides strong coupling between the two GaAs quantum wells which have equal widths. Photoluminescence (PL) arises from both spatially direct and spatially indirect transitions in the quantum wells. The intense spatially indirect transition shows a pronounced red shift with increasing bias. A strong intrinsic bistability effect is observed in one of the three resonant peaks in the current-voltage curve. This effect is also seen in the photon energy and intensity of the PL from the wells. Photoluminescence excitation spectroscopy is used to identify the optical transitions and the strength of the tunneling interaction.