Photoconductive response of InAs/GaAs quantum dot stacks

We investigate the energy levels of self-assembled InAs/GaAs quantum dot stacks by photoluminescence and vertical photocurrent spectroscopy. This leads to a photodetector with two response peaks at 55 and View the MathML source due to interdot and dot-continuum transitions. Two samples are used for the investigations: one without and one with AlAs barriers between the dot layers to restrict the vertical current. These barriers have a strong influence on the signal height of the room temperature photoluminescence. They make—due to the lower dark current and lower noise—the interdot transitions visible in photocurrent spectroscopy and increase the dot-continuum photocurrent energy by the amount of the first miniband energy level of the AlAs/GaAs superlattice.